Research progress in controllable proteolysis targeting chimeras / 药学学报

Proteolysis targeting chimeras (PROTACs) is an innovative technique in targeted protein degradation. PROTACs is a heterobifunctional molecule which can bind to the E3 ligase and target protein to form a ubiquitination complex, resulting in the ubiquitin-proteasome system dependent degradation of target protein. PROTACs has been regarded as the promising method in drug discovery campaign, for its high commonality, potent degradation activity and unique selectivity profile. However, the catalytic mechanism also induces the uncontrollable protein degradation risk. Controllable PROTACs contain the responsive element in the molecular entity. In certain conditions, the element can be triggered to activate or terminate the degradation event. In this review, we will briefly summarize the strategies in controllable PROTACs and describe the representative examples according to the responsive mechanism. We hope this review could provide some insight into the further development of controllable PROTACs.

Application of PROTACs in Hematological Malignancies--Review / 中国实验血液学杂志

Proteolysis-targeting chimeras (PROTACs) are heterobifunctional small molecules by utilizing the ubiquitin proteasome system (UPS) to degrade proteins of interest. PROTACs have exhibited unprecedented efficacy and specificity in degrading various oncogenic proteins because of their unique mechanism of action, ability to target "undruggable" and mutant proteins. A series of PROTACs have been developed to degrade multiple key protein targets for the treatment of hematologic malignancy. Notably, PROTACs that target BCL-XL, IRAK4, STAT3 and BTK have entered clinical trials. The known PROTACs that have the potential to be used to treat various hematological malignancies are systematically summarized in this review.

Advances in targeted delivery of proteolysis targeting chimeras in cancer therapy / 生物工程学报

Small-molecule anticancer drugs inhibited tumor growth based on targeted inhibition of specific proteins, while most of oncogenic proteins are "undruggable". Proteolysis targeting chimeras (PROTAC) is an attractive and general strategy for treating cancer based on targeted degradation of oncogenic proteins. This review briefly describes the peptide-based PTOTAC and small molecule-based PROTAC. Subsequently, we summarize the development of targeted delivery of PROTAC, such as targeting molecule-mediated targeted delivery of PROTAC, nanomaterial-mediated targeted delivery of PROTAC and controllable activation of small-molecular PROTAC prodrug. Such strategies show potential application in improving tumor selectivity, overcoming off-target effect and reducing biotoxicity. At the end, the druggability of PROTAC is prospected.

Advances in the preclinical and clinical research of proteolysis targeting chimera / 生物工程学报

Proteolysis targeting chimera (PROTAC) refers to heterobifunctional small molecules that can simultaneously bind an E3 ubiquitin ligase and a target protein, enabling specific degradation of the target protein with the aid of the ubiquitin proteasome system. At present, most PROTAC drugs are in the clinical trial stage, and the ligands are mainly non-covalent compounds. PROTAC drugs have the advantage of overcoming drug resistance and degrading "undruggable" target proteins, but non-covalent ligands could lead to the hook effect that undermines drug efficacy. With its own advantages, covalent ligands can avoid the occurrence of this phenomenon, which is of great help to the development of PROTAC. This review summarizes the progress in preclinical and clinical research and application of PROTAC molecules targeting three different classes of protein targets, including intranuclear, transmembrane, and cytosolic proteins. We also offer perspective discussions to provide research ideas and references for the future development of PROTAC.

Discovery of novel exceptionally potent and orally active c-MET PROTACs for the treatment of tumors with MET alterations

Various c-mesenchymal-to-epithelial transition (c-MET) inhibitors are effective in the treatment of non-small cell lung cancer; however, the inevitable drug resistance remains a challenge, limiting their clinical efficacy. Therefore, novel strategies targeting c-MET are urgently required. Herein, through rational structure optimization, we obtained novel exceptionally potent and orally active c-MET proteolysis targeting chimeras (PROTACs) namely D10 and D15 based on thalidomide and tepotinib. D10 and D15 inhibited cell growth with low nanomolar IC50 values and achieved picomolar DC50 values and >99% of maximum degradation (Dmax) in EBC-1 and Hs746T cells. Mechanistically, D10 and D15 dramatically induced cell apoptosis, G1 cell cycle arrest and inhibited cell migration and invasion. Notably, intraperitoneal administration of D10 and D15 significantly inhibited tumor growth in the EBC-1 xenograft model and oral administration of D15 induced approximately complete tumor suppression in the Hs746T xenograft model with well-tolerated dose-schedules. Furthermore, D10 and D15 exerted significant anti-tumor effect in cells with c-METY1230H and c-METD1228N mutations, which are resistant to tepotinib in clinic. These findings demonstrated that D10 and D15 could serve as candidates for the treatment of tumors with MET alterations.

The dichotomous role of immunoproteasome in cancer: Friend or foe?

Immunoproteasome is a variant of proteasome with structural differences in 20S subunits optimizing them for the production of antigenic peptides with higher binding affinity to major histocompatibility complex (MHC)-I molecules. Apart from this primary function in antigen presentation, immunoproteasome is also responsible for the degradation of proteins, both unfolded proteins for the maintenance of protein homeostasis and tumor suppressor proteins contributing to tumor progression. The altered expression of immunoproteasome is frequently observed in cancers; however, its expression levels and effects vary among different cancer types exhibiting antagonistic roles in tumor development. This review focuses on the dichotomous role of immunoproteasome in different cancer types, as well as summarizes the current progression in immunoproteasome activators and inhibitors. Specifically targeting immunoproteasome may be a beneficial therapeutic intervention in cancer treatment and understanding the role of immunoproteasome in cancers will provide a significant therapeutic insight for the prevention and treatment of cancers.

TRIB3 promotes pulmonary fibrosis through inhibiting SLUG degradation by physically interacting with MDM2

Pulmonary fibrosis (PF) is the pathological structure of incurable fibroproliferative lung diseases that are attributed to the repeated lung injury-caused failure of lung alveolar regeneration (LAR). Here, we report that repetitive lung damage results in a progressive accumulation of the transcriptional repressor SLUG in alveolar epithelial type II cells (AEC2s). The abnormal increased SLUG inhibits AEC2s from self-renewal and differentiation into alveolar epithelial type I cells (AEC1s). We found that the elevated SLUG represses the expression of the phosphate transporter SLC34A2 in AEC2s, which reduces intracellular phosphate and represses the phosphorylation of JNK and P38 MAPK, two critical kinases supporting LAR, leading to LAR failure. TRIB3, a stress sensor, interacts with the E3 ligase MDM2 to suppress SLUG degradation in AEC2s by impeding MDM2-catalyzed SLUG ubiquitination. Targeting SLUG degradation by disturbing the TRIB3/MDM2 interaction using a new synthetic staple peptide restores LAR capacity and exhibits potent therapeutic efficacy against experimental PF. Our study reveals a mechanism of the TRIB3-MDM2-SLUG-SLC34A2 axis causing the LAR failure in PF, which confers a potential strategy for treating patients with fibroproliferative lung diseases.

Research on technological innovation of PROTAC in China from the perspective of patent / 中国药房

OBJECTIVE To provide information service support for research on proteolysis targeting chimera （PROTAC） in China and provide reference for technical development and patent layout of relevant drug research and development institutions. METHODS The patent analysis method was used to search the patent applications related to PROTAC technology that had been applied to China National Intellectual Property Administration and had been issued before Feb. 2022， using the HimmPat patent database as the search platform. The patent application trend， technology life cycle， main applicants， technology source countries， technology themes， improvement routes and other patent data were analyzed. RESULTS & CONCLUSIONS A total of 133 patents were included in this study. The patent application for PROTAC technology started relatively late in China， with the number of applicants increasing from 2 in 2015 to 30 in 2020， and the number of applications increasing from 2 in 2015 to 38 in 2020. Both the annual patent application volume and the number of applicants were in a period of rapid growth， but the average annual application volume of a single applicant was still less than 2， indicating that research in this field was still in the early stage of technology development； the number of applications from Arvinas， Hisco， and Hinova Pharmaceutical Inc. ranked among the top. Although the number of domestic applications led that of foreign applications in China， the average number of simple peer applications and the average number of simple peer countries in domestic patent applications was only 1.5， which was far lower than that of foreign applications in China， reflecting that there was still room for improvement in the “quality” level of domestic applications. The initial improvements in PROTAC technology mainly focused on the selection of E3 ligands， targets and ligands， and then new improvements such as new PROTAC development， linker design and matching methods emerged， indicating that the patent applicant had started a multi-track layout in the early stages of the development of PROTAC technology. It is suggested that the research and development of PROTAC drugs in China should focus on improving the oral bioavailability and biosafety of PROTAC drugs， overcoming potential drug resistance， and exploring rational design and evaluation methods.

Research advances in new technologies in targeted protein degradation / 药学学报

In recent years, the targeted protein degradation technology has developed quickly, with proteolysis-targeting chimera (PROTAC) as the best-known strategy through exploring the ubiquitin-proteasome system. A number of new targeted protein degradation strategies have been emerging to expand the scope of protein degradation technology, including lysosome-targeting chimeras (LYTACs), autophagy-targeting chimeras (AUTACs), autophagosome-tethering compounds (ATTECs) and chimeras based on chaperone-mediated autophagy (CMA). The emerging methodologies have explored another important protein degradation system in eukaryotes-lysosomal systems, such as the endosome-lysosome pathway and the autophagy-lysosome pathway. This review summaries the mechanisms and features of different strategies for targeted protein degradation, with a special emphasis on the new targeted protein degradation technologies, such as their current status, advantages and limitations.

Research Progress of Proteolysis Targeting Chimeria in NSCLC Therapy / 中国肺癌杂志

Proteolysis targeting chimeria (PROTAC) degrades target proteins by utilizing the ubiquitin-proteasome pathway, subverting the concept of traditional small molecule inhibitors. Among the common mutation targets of non-small cell lung cancer (NSCLC), PROTAC technology has successfully achieved the effective degradation of kirsten rat sarcoma viral oncogene homolog (KRAS), epidermal growth factor receptor (EGFR), anaplastic lymphoma kinase (ALK ) and other proteins in preclinical studies. PROTAC drugs with their unique event-driven advantages, are expected to overcome acquired drug resistance caused by small molecule inhibitors and show good therapeutic potential for undruggable targets, thereby providing a new strategy for the treatment of NSCLC.
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Recent progress of targeted small molecular CDK9 degraders based on PROTAC technology / 药学学报

CDKs proteins are a kind of cell cycle protein-dependent kinases, which serve as important roles in controlling cell division and transcriptional stages. Among them, CDK9, as a key regulator responsible for the transcriptional elongation of cells, drives the development of various malignant cells and is considered as an important target in the field of anti-tumor drug development. However, the CDK family proteins feature high conservativeness and similarity in structure, leading to the poor selectivity and severe side effects for traditional small-molecular CDK9 inhibitors, which has limited their clinical applications. In view of this, there is an urgent need to investigate CDK9 targets through a novel strategy. The PROTAC is an emerging drug discovery strategy that the degrader could specifically recognize the target protein through indirect linkage with ubiquitin ligases and ultimately eliminate the target protein through the ubiquitination degradation system. This paper provides a brief overview of the structure and function of CDK9 protein, its relationship with the poor prognosis of clinical diseases, as well as the currently reported small molecular inhibitors. The latest research progress on the targeted degradation of CDK9 protein based on PROTAC technology is highlighted. Finally, the development prospects of this target protein in this novel technology field are summarized and prospected, aiming to provide a reference for the development of antitumor drugs in this direction.

Amiloidosis AL: conceptos actuales / AL amyloidosis: current concepts

Las amiloidosis sistémicas constituyen un grupo de enfermedades con diversas etiologías, caracterizadas por la síntesis de proteínas con plegado defectuoso, capaces de agregarse y depositarse en el medio extracelular de diferentes órganos y tejidos, alterando su estructura y función. Se conocen más de 14 formas de amiloidosis sistémica, de las cuales la más frecuente es la amiloidosis AL, objeto de esta revisión, en la que las proteínas precursoras son cadenas ligeras de inmunoglobulina inestables, secretadas por un clon de células plasmáticas o, con menor frecuencia, por un linfoma linfoplasmocítico o de células del manto. La amiloidosis AL puede llevar a una amplia gama de manifestaciones clínicas y compromiso de órganos, como el corazón y el riñón. El reconocimiento temprano de la enfermedad y el diagnóstico oportuno son determinantes para mejorar la supervivencia de los pacientes. El tratamiento deberá ser individualizado de acuerdo con la condición de cada paciente, lo que hace necesaria una correcta clasificación de los individuos según su pronóstico. La terapia dirigida a la amiloidosis está enfocada esencialmente en disminuir el compromiso orgánico, y por ende, prolongar la supervivencia con mejoría en los síntomas. En esta revisión se discutirán aspectos importantes de la fisiopatología, epidemiología, manifestaciones clínicas, diagnóstico y tratamiento de la amiloidosis AL

Systemic amyloidosis constitutes a group of diseases with diverse etiologies characterized by the synthesis of proteins with defective folding, capable of aggregating and depositing in the extracellular matrix of different organs and tissues, altering their structure and function. More than 14 forms of systemic amyloidosis are known, of which the most frequent is AL amyloidosis, the subject of this review, in which the precursor proteins are unstable immunoglobulin light chains, secreted by a clone of plasma cells or, to a lesser extent, often due to lymphoplasmacytic or mantle cell lymphoma. AL amyloidosis can lead to a wide range of clinical manifestations and organ involvement, such as the heart and kidney. Early recognition of the disease and timely diagnosis are crucial to improve patient survival. Treatment should be individualized according to the condition of each patient, which requires a properly classification of individuals according to their prognosis. Amyloidosis-targeted therapy is essentially focused on reducing organ involvement, and therefore prolonging survival with improvement in symptoms. In this review, important aspects of the pathophysiology, epidemiology, clinical manifestations, diagnosis, and treatment of AL amyloidosis are discussed

Venenos de serpentes do gênero Bothrops: impacto da glicosilação na complexidade dos proteomas e função de toxinas / Bothrops snake venoms: impact of glycosylation on the complexity of proteomes and toxins function

A variabilidade estrutural é uma característica das proteínas de venenos de serpentes, e a glicosilação é uma das principais modificações pós-traducionais que contribui para a diversificação de seus proteomas. Recentes estudos de nosso grupo demonstraram que venenos do gênero Bothrops são marcadamente definidos pelo seu conteúdo de glicoproteínas, e que a maioria das estruturas de N-glicanos dos tipos híbrido e complexo identificados em oito venenos deste gênero contêm unidades de ácido siálico. Em paralelo, em glicoproteínas do veneno de B. cotiara foi identificada a presença de uma estrutura de N-acetilglicosamina bissecada. Assim, com o objetivo de investigar a variação do conteúdo de glicoproteínas, assim como os mecanismos envolvidos na geração dos diferentes venenos de Bothrops, neste estudo foram analisados comparativamente os glicoproteomas de nove venenos do gênero Bothrops (B. atrox, B. cotiara, B. erythromelas, B. fonsecai, B. insularis, B. jararaca, B. jararacussu, B. moojeni e B. neuwiedi). As abordagens glicoproteômicas envolveram cromatografia de afinidade e ensaio de pull-down utilizando, respectivamente, as lectinas SNA (aglutinina de Sambucus nigra) e MAL I (lectina de Maackia amurensis), que mostram afinidade por unidades de ácido siálico nas posições, respectivamente, α2,6 e α2,3; e cromatografia de afinidade com a lectina PHA-E (eritroaglutinina de Phaseolus vulgaris), que reconhece N-acetilglicosamina bissecada. Ainda, eletroforese de proteínas, blot de lectina, e identificação de proteínas por espectrometria de massas foram empregadas para caracterizar os glicoproteomas. As lectinas geraram frações dos venenos enriquecidas de diferentes componentes, onde as principais classes de glicoproteínas identificadas foram metaloprotease, serinoprotease, e L-amino ácido oxidase, além de outras enzimas pouco abundantes nos venenos. Os diferentes conteúdos de proteínas reconhecidas por essas lectinas, com especificidades distintas, ressaltaram novos aspectos da variabilidade dos subproteomas de glicoproteínas desses venenos, dependendo da espécie. Ainda, considerando que metaloproteases e serinoproteases são componentes abundantes nesses venenos e fundamentais no quadro de envenenamento botrópico, e que estas enzimas contêm diversos sítios de glicosilação, o papel das unidades de ácido siálico na atividade proteolítica das mesmas foi avaliado. Assim, a remoção enzimática de ácido siálico (i) alterou o padrão de gelatinólise em zimografia da maioria dos venenos, (ii) diminuiu a atividade proteolítica de alguns venenos sobre o fibrinogênio e a atividade coagulante do plasma humano de todos os venenos, e (iii) alterou o perfil de hidrólise de proteínas plasmáticas pelo veneno de B. jararaca, indicando que este carboidrato pode desempenhar um papel na interação das proteases com seus substratos proteicos. Em contraste, o perfil da atividade amidolítica dos venenos não se alterou após a remoção de ácido siálico e incubação com o substrato Bz-Arg-pNA, indicando que ácido siálico não é essencial em N-glicanos de serinoproteases atuando sobre substratos não proteicos. Em conjunto, esses resultados expandem o conhecimento sobre a variabilidade de proteomas de venenos do gênero Bothrops e apontam a importância das cadeias de carboidratos contendo ácido siálico nas atividades enzimáticas das proteases desses venenos

Structural variability is a feature of snake venom proteins, and glycosylation is one of the main post-translational modifications that contributes to the diversification of venom proteomes. Recent studies by our group have shown that Bothrops venoms are markedly defined by their glycoprotein content, and that most hybrid and complex N-glycan structures identified in eight venoms of this genus contain sialic acid units. In parallel, the presence of a bisected N-acetylglucosamine structure was identified in B. cotiara venom glycoproteins. Thus, with the aim of investigating the variation in the content of glycoproteins, as well as the mechanisms involved in the generation of different Bothrops venoms, in this study the glycoproteomes of nine Bothrops venoms (B. atrox, B. cotiara, B. erythromelas, B. fonsecai, B. insularis, B. jararaca, B. jararacussu, B. moojeni e B. neuwiedi) were comparatively analyzed. The glycoproteomic approaches involved affinity chromatography and pulldown using, respectively, the lectins SNA (Sambucus nigra agglutinin) and MAL I (Maackia amurensis lectin), which show affinity for sialic acid units at positions, respectively, α2,6 and α2,3, and affinity chromatography with PHA-E (Phaseolus vulgaris erythroagglutinin), which recognizes bisected N-acetylglucosamine. In addition, protein electrophoresis, lectin blot, and protein identification by mass spectrometry were employed for glycoproteome characterization. The lectins generated venom fractions enriched with different components, where the main classes of glycoproteins identified were metalloprotease, serine protease, and L-amino acid oxidase, in addition to other low abundant enzymes. The different contents of proteins recognized by these lectins of distinct specificities highlighted new aspects of the variability of the glycoprotein subproteomes of these venoms, depending on the species. Furthermore, considering that metalloproteases and serine proteases are abundant components of these venoms and essential in Bothrops envenomation, and that these enzymes contain several glycosylation sites, the role of sialic acid units in their proteolytic activities was evaluated. Thus, enzymatic removal of sialic acid (i) altered the pattern of gelatinolysis in zymography of most venoms, (ii) decreased the proteolytic activity of some venoms on fibrinogen and the clotting activity of human plasma of all venoms, and (iii) altered the hydrolysis profile of plasma proteins by B. jararaca venom, indicating that this carbohydrate may play a role in the interaction of proteases with their protein substrates. In contrast, the profile of amidolytic activity of the venoms did not change after removal of sialic acid and incubation with the substrate Bz-Arg-pNA, indicating that sialic acid is not essential in N-glycans of serine proteases acting on small substrates. Together, these results expand the knowledge about the variability of proteomes of Bothrops venoms and point to the importance of carbohydrate chains containing sialic acid in the enzymatic activities of venom proteases

Advances of targeted protein degradation technology and its applications in diseases therapy / 生物工程学报

Targeted protein degradation (TPD) technology facilitates specific and efficient degradation of disease-related proteins through hijacking the two major protein degradation systems in mammalian cells: ubiquitin-proteasome system and lysosome pathway. Compared with traditional small molecule-inhibitors, TPD-based drugs exhibit the characteristics of a broader target spectrum. Compared with techniques interfere with protein expression on the gene and mRNA level, TPD-based drugs are target-specific, efficaciously rapid, and not constrained by post-translational modification of proteins. In the past 20 years, various TPD-based technologies have been developed. Most excitingly, two TPD-based therapeutic drugs have been approved by FDA for phase Ⅰ clinical trials in 2019. Despite of the early stage characteristics and various obstructions of the TPD technology, it could serve as a powerful tool for the development of novel drugs. This review summarizes the advances of different degradation systems based on TPD technologies and their applications in disease therapy. Moreover, the advantages and challenges of various technologies were discussed systematically, with the aim to provide theoretical guidance for further application of TPD technologies in scientific research and drug development.

Recent progress in targeting degradation of FAK based on PROTAC / 药学学报

Local focal adhesion kinase (FAK) is a non-receptor intracellular tyrosine kinase that plays an important role in tumor initiation, development, metastasis and invasion, and is considered to be an important target for the development of antineoplastic drugs. It has both kinase-dependent and non-kinase-dependent scaffolding functions. However, traditional small molecular inhibitors can only inhibit its kinase-dependent activity, so it is difficult to target the kinase-independent scaffolding function. Therefore, there is an urgent need for novel strategies to enhance FAK targeting to lay the foundation for determining the druggability and discovery of FAK inhibitors. Proteolysis targeting chimera (PROTAC) is a new drug development strategy that can recruit E3 ligase to specifically ubiquitinylate target proteins for degradation through the proteasome system. The unique mechanism of action of the PROTAC system could be used to target and degrade the FAK protein, thus eliminating the scaffolding function of FAK. In this review, FAK protein, the signaling pathway, and small molecule inhibitors are briefly described, and the latest research progress in targeting the degradation of FAK using PROTAC technology is summarized.

Recent advancement in targeting the KRAS-G12C mutant for cancer therapy / 药学学报

RAS, as a well-known proto-oncogene, is the most frequently mutated oncogene in human cancers, yet tremendous efforts over the past 30 years have failed to develop effective therapies for RAS-mutant cancer. Recently, specifically targeting the KRAS-G12C mutant, a frequently occurring KRAS mutation in human cancers, has shown promise in conquering KRAS-mutant cancers, and has inspired interest in this direction. We herein review the very recent progress achieved in the development of covalent inhibitors towards KRAS-G12C mutant, in combinational therapies and in proteolysis-targeting chimeras (PROTACs)-based approaches to disrupt KRAS-G12C protein. We provide insights for drug discovery against KRAS-G12C-mutated tumors and discuss the potential challenges in this field.

Advances in the optimization of the linker in proteolysis-targeting chimeras (PROTAC) / 药学学报

With high selectivity and potency, target protein degradation technology has recently emerged as a strategy for drug discovery and design. Proteolysis-targeting chimeras (PROTAC) function as inducers for the degradation of target proteins and are a research focus in drug development. Current research on PROTAC mainly revolves around the rational design of PROTAC molecules, the discovery of new E3 ubiquitin ligase ligands and improvement in drug targeting. In this review, we focus on the PROTAC linker and its effects on the generation of the E3 enzyme-PROTAC-target protein ternary complex from three standpoints: length, binding site and chemical properties. We discuss the influences of the linker on the efficacy and the selectivity of PROTAC molecules.

Progress of drugs targeting E3 ubiquitin ligase / 中国药理学通报

The ubiquitin-proteasome pathway is one of the most important pathways of cell protein degradation in eukaryotes, and plays an important role in the regulation of cell proliferation, differentiation, apoptosis, DNA repair and other physiological activities. E3 ubiquitin ligase is the major component of ubiquitinproteasome system, which is responsible for substrate recognition. The abnormal regulation of E3 ubiquitin ligase may cause many diseases such as cancer, Alzheimer's disease and Parkinson's disease. Here, we summarizes the progress of drugs targeting E3 ubiquitin ligase in cancer, Alzheimer's disease, Parkinson's disease, diabetic complications, atherosclerosis, and inflammatory bowel diseases. At present, only a few of small molecule antagonists or agonists targeting E3 ubiquitin ligase are under development. The study of natural products in China is leading the way in the world, and numerous natural products have been identified for pharmacological effects on E3 ubiquitin ligase, which may open up a new avenue for multiple complex diseases.

Examples of biology-driven drug design / 药学学报

Pharmacological activity and drug likeness depend in principle upon the microscopic structure and macroscopic properties of drugs, which reside in their molecular structures. By means of medicinal chemistry the evolution of an active compound to a novel drug (NME) essentially makes the two pillars coexistence in one chemical structure, which either could merge as an intrinsic structure or connect from external fragments to each other with covalent bonds. Since the new millennium the advance in biology provides several knowledge and technologies, for example humanized monoclonal antibody, proteasome-ubiquitin system, allosteric modulation, natural macromolecules, structural biology, etc., for innovation of novel medicines. Taking several examples on marketed drugs or drug candidates in clinical trials, this article tries to concisely illustrate R & D conception of biology-driven drug design.

Pseudomonas spp. and other psychrotrophic microorganisms in inspected and non-inspected Brazilian Minas Frescal cheese: proteolytic, lipolytic and AprX production potential / Pseudomonas spp. e outros micro-organismos psicrotróficos em queijos Minas Frescal inspecionados e não inspecionados: potencial proteolítico, lipolítico e produção de AprX

The most consumed cheese in Brazil, Minas Frescal cheese (MFC) is highly susceptible to microbial contamination and clandestine production and commercialization can pose a risk to consumer health. The storage of this fresh product under refrigeration, although more appropriate, may favor the growth of spoilage psychrotrophic bacteria. The objective of this study was to quantify and compare Pseudomonas spp. and other psychrotrophic bacteria in inspected and non-inspected MFC samples, evaluate their lipolytic and proteolytic activities and their metalloprotease production potentials. Twenty MFC samples were evaluated: 10 inspected and 10 non-inspected. Counts of psychrotrophic bacteria and Pseudomonas spp., evaluation of the proteolytic and lipolytic potential of the isolates, and identification of potential producers of alkaline metalloprotease (AprX) were assessed. The mean total psychrotrophic counts were 1.07 (±2.18) × 109CFU/g in the inspected samples and 4.5 (±5.86) × 108CFU/g in the non-inspected, with no significant difference (p=0.37). The average score of Pseudomonas spp. was 6.86 (±18.6) × 105 and 2.08 (±3.65) × 106 CFU/g for the inspected and non-inspected MFC samples, respectively, with no significant difference (p=0.1). Pseudomonas spp. represented 0.06% and 0.004% of psychrotrophic bacteria found in inspected and non-inspected MFC samples, respectively. Collectively, 694 psychrotrophic strains and 47Pseudomonas spp. were isolated, of which 59.9% and 68.1% were simultaneously proteolytic and lipolytic, respectively. Of the 470 psychrotrophs isolated from inspected and 224 from non-inspected cheese samples, 5.74% and 2.23% contained aprX, respectively, while 100 and 86.96% of the Pseudomonas spp. isolates in inspected and non-inspected cheese samples contained the gene. The production potential of AprX did not, however, determine the proteolytic activity on plates of these isolates under the conditions evaluated in this study. Of total, 65.63% of the psychrotrophs that contained aprX gene were confirmed as Pseudomonas spp., using genus-specific PCR. Phylogenetic analysis of the 16S rRNA gene of the other psychrotrophs that were potential producers of AprX identified them as Serratia spp. (n=7), Raoultella ornithinolytica (n=1), and Acinetobacter schindleri (n=1) in the inspected samples and Psychrobacter sanguinis (n=1) and Leuconostoc mesenteroides (n=1) in the non-inspected samples. The production conditions of Brazilian MFC of these samples, while meeting the legal determinations, are not sufficient to control Pseudomonas and other spoilage-related psychrotrophs. Thus, stricter hygienic measures are required during the formal production of this type of cheese.(AU)

O mais consumido no Brasil, o queijo Minas Frescal (QMF) é altamente suscetível à contaminação microbiana e a produção e comercialização clandestina podem representar um risco para a saúde do consumidor. O armazenamento deste produto fresco sob refrigeração, embora mais apropriado, pode favorecer a multiplicação de bactérias psicrotróficas deteriorantes. O objetivo deste estudo foi quantificar e comparar Pseudomonas spp. e outras bactérias psicrotróficas em amostras de QMF inspecionadas e não inspecionadas, avaliar o potencial lipolítico, proteolítico e de produção de metaloprotease alcalina. Vinte amostras de QMF foram avaliadas: 10 inspecionadas e 10 não inspecionadas. Foram avaliadas as contagens de bactérias psicrotróficas e Pseudomonas spp., o potencial proteolítico e lipolítico dos isolados e a identificação de potenciais produtores de metaloprotease alcalina (AprX). A média total das contagens de bactérias psicrotróficas foi de 1,07 (±2,18) × 109UFC/g nas amostras inspecionadas e 4,5 (±5,86) × 108UFC/g nas não inspecionadas, sem diferença significativa (p=0,37). A média de Pseudomonasspp. foi de 6,86 (±18,6) × 105 e 2,08 (±3,65) × 106UFC/g para as amostras QMF inspecionadas e não-inspecionadas, respectivamente, sem diferença significativa (p=0,1). Pseudomonas spp. representaram 0,06% e 0,004% de bactérias psicrotróficas encontradas em amostras QMF inspecionadas e não-inspecionadas, respectivamente. Das amostras inspecionadas e não inspecionadas, foram isoladas 694 colônias psicrotróficas e 47 Pseudomonasspp., dos quais 59,9% e 68,1% foram simultaneamente proteolíticos e lipolíticos, respectivamente. Dos 470 isolados de psicrotróficos das amostras de queijo inspecionados e dos 224 isolados das não inspecionadas, 5,74% e 2,23% continham o gene aprX, respectivamente, enquanto 100 e 86,96% das Pseudomonasspp. isoladas em amostras de queijo inspecionadas e não inspecionadas continham o potencial de expressão de AprX. Esse potencial, no entanto, não determinou a atividade proteolítica em placas desses isolados nas condições avaliadas neste estudo. Do total, 65,63% dos psicrotróficos que continham o gene aprX foram confirmados como Pseudomonasspp., utilizando PCR gênero-específico. A análise filogenética do gene 16S rRNA dos outros psicrotróficos que foram produtores potenciais de AprX os identificou como Serratia spp. (n=7), Raoultella ornithinolytica (n=1) e Acinetobacter schindleri (n=1) nas amostras inspecionadas e Psychrobacter sanguinis (n=1) e Leuconostoc mesenteroides (n=1) nas amostras não inspecionadas. As condições de produção do QMF dessas amostras, atendendo às determinações legais, não são suficientes para controlar a Pseudomonas e outros psicrotróficos relacionados à deterioração. Assim, medidas higiênicas mais rígidas são necessárias durante a produção formal deste tipo de queijo.(AU)