RESUMO
Invasive micropapillary carcinoma (IMPC) of the breast represents a rare subtype of breast cancer, accounting for 1% to 2% of all breast cancers worldwide. Although clinically asymptomatic, they are usually detected during routine breast screenings. The common symptoms include breast lumps, skin or nipple changes, and nipple discharge. Histopathologically, IMPCs are characterized by tumor cells forming small papillary-like structures inside the glandular spaces, and arranged in an inverted pattern, with their apex pointing toward the center of the gland. This unique morphological feature is critical for diagnosing these cases. Another notable characteristic is its high propensity for lymph node metastasis (LNM). While the precise mechanism of metastasis is not clear, unique cellular arrangement and cellular interactions with the surrounding environment might promote tumorigenesis and higher node positivity. Hence, proper lymph node dissection and assessment are particularly crucial for this type of breast cancer. This review aims to discuss the recent progress in managing IMPC cases.
Assuntos
Neoplasias da Mama , Carcinoma Papilar , Carcinoma , Humanos , Feminino , Mamilos , CarcinogêneseRESUMO
The sensitive detection of neuron-specific enolase (NSE) as a biomarker for lung cancer at an early stage is critical but has long been a challenge. The emergence of polarity-switchable photoelectrochemical (PEC) bioanalysis has opened up new avenues for developing highly sensitive NSE sensors. In this study, we present such a biosensor depending on the bioinduced AgI transition on MOF-on-MOF-derived semiconductor heterojunctions. Specifically, treatment of ZnO@In2O3@AgI by bioproduced H2S can in situ generate the ZnO@In2O3@In2S3@Ag2S heterojunction, with the photocurrent switching from the cathodic to anodic one due to the changes in the carrier transfer pathway. Linking an NSE-targeted sandwich immunorecognition with labeled alkaline phosphatase (ALP) catalyzed generation of H2S, such a phenomenon was correlated to NSE concentration with good performance in terms of selectivity and sensitivity and a low detection limit of 0.58 pg/mL. This study offered a new perspective on the use of MOF-on-MOF-derived heterostructures for advanced polarity-switchable PEC bioanalysis.
Assuntos
Técnicas Biossensoriais , Óxido de Zinco , Semicondutores , Fosfopiruvato Hidratase/análise , Eletrodos , Técnicas Eletroquímicas , Limite de DetecçãoRESUMO
BACKGROUND AND AIMS: The quality of EGD is a prerequisite for a high detection rate of upper GI lesions, especially early gastric cancer. Our previous study showed that an artificial intelligence system, named intelligent detection endoscopic assistant (IDEA), could help to monitor blind spots and provide an operation score during EGD. Here, we verified the effectiveness of IDEA to help evaluate the quality of EGD in a large-scale multicenter trial. METHODS: Patients undergoing EGD in 12 hospitals were consecutively enrolled. All hospitals were equipped with IDEA developed using deep convolutional neural networks and long short-term memory. Patients were examined by EGD, and the results were recorded by IDEA. The primary outcome was the detection rate of upper GI cancer. Secondary outcomes were part scores, total scores, and endoscopic procedure time, which were analyzed by IDEA. RESULTS: A total of 17,787 patients were recruited. The total detection rate of cancer-positive cases was 1.50%, ranging from .60% to 3.94% in each hospital. The total detection rate of early cancer-positive cases was .36%, ranging from .00% to 1.58% in each hospital. The average total score analyzed by IDEA ranged from 64.87 ± 16.87 to 83.50 ± 9.57 in each hospital. The cancer detection rate in each hospital was positively correlated with total score (r = .775, P = .003). Similarly, the early cancer detection rate was positively correlated with total score (r = .756, P = .004). CONCLUSIONS: This multicenter trial confirmed that the quality of the EGD result is positively correlated with the detection rate of cancer, which can be monitored by IDEA. (Clinical trial registration number: ChiCTR2000029001.).
Assuntos
Neoplasias Gastrointestinais , Neoplasias Gástricas , Inteligência Artificial , Endoscopia , Endoscopia do Sistema Digestório/métodos , Humanos , Redes Neurais de Computação , Neoplasias Gástricas/diagnósticoRESUMO
OBJECTIVE: To observe the effect of electroacupuncture (EA) combined with caudal epidural injection on subjective pain, walking capability, lumbar flexibility and muscle strength in patients with lumbar disc hernia (LDH). METHODS: Sixty LDH patients were randomly allocated to the control group and the research group. The patients of the control group received ultrasound guided caudal epidural injection, and those of the research group received EA combined with ultrasound guided caudal epidural injection. Bilateral Jiaji (EX-B2) and adjunct points Guanyuanshu (BL26), Shenshu (BL23), Chengfu (BL36), Huantiao (GB30), Zhibian (BL54), etc. on the affected side were stimulated with EA (2 Hz/16 Hz, 5-8 mA) for 30 min each time, once every other day for 4 weeks, with 2 days' rest between every two weeks. The patients' pain was evaluated by using visual analogue scale (VAS), walking capability assessed by timed-up and go (TUG) test (time of walking back and forth in 3 m distance), lumbar flexibility (range of motion, ROM) detected by using an inclinometer and the strength of the lumbar flexor and extensor determined by using a push-pull dynamometer. RESULTS: After the treatment, self-comparison showed that the VAS score and TUG-measured time in both groups were significantly decreased (P<0.01, P<0.05), and the post-bucking ROM and extension ROM in the research group, and the lumbar flexor and extensor muscle strength in both groups were obviously increased compared with their own pre-treatment (P<0.05). Comparison between two groups showed that the VAS score and TUG-measured time of the research group were significantly lower than those of the control group (P<0.01), while the lumbar flexor's ROM as well as the extensor's strength were significantly higher in the research group than in the control group (P<0.05). CONCLUSION: For patients with LDH, EA combined with caudal epidural injection can alleviate pain, improve the walking capability, lumbar flexibility and strength of the lumbar extensor, and the therapeutic effect of the combined treatment is significantly better than that of simple caudal epidural injection.
Assuntos
Eletroacupuntura , Hérnia , Humanos , Injeções Epidurais , Dor , CaminhadaRESUMO
Efficient separation of photogenerated electron-hole pairs is always one of the key factors boosting visible light photodegradation efficiency. Till now, there are few reports on the synergistic competitive consumption of photogenerated active species and the synergistic adsorption of organic contaminants to promote the performance of a designed heterojunction. Herein, we design and construct a novel BiOBr/Ag6Si2O7 heterojunction with the dual synergistic effects towards methylene blue (MB) and methyl orange (MO). The dual synergistic effects could avoid the combination of photogenerated h+/e- pairs, improve the adsorption efficiency, and even regulate the photodegradation efficiency. Thus, for an aqueous mixture of MB and MO, the BiOBr/Ag6Si2O7 photocatalyst exhibits largely improved adsorption capacities of the dyes by a multi-layer adsorption mode. Moreover, the photocatalyst could further promote the photodegradation rate of MO while slow that of MB due to the competitive consumption of photogenerated active species, showing a sequential selectivity phenomenon. Thanks to the dual synergistic effects, the adsorption capacity of MO increases 1379% higher than that of neat MO solution, and the photodegradation time decrease from 30 to 12â¯min with a rate constant of 0.22â¯min-1, 38% higher than that of neat MO solution.
RESUMO
Macroscopic three-dimensional catalytic materials could overcome the poor operability and avoid secondary pollution of common powdery counterparts, especially in flow-type setups. However, conventional isotropic graphene-based aerogels and foams have randomly distributed graphene sheets, which may cause stream erosion and reduce the flux seriously. Herein, for the first time, we design and fabricate a novel anisotropic CoFe2O4@graphene hybrid aerogel (CFO@GA-A) with a hydrothermal synthesis followed by directional-freezing and freeze-drying for a tube-like flow-type setup analogous to a wastewater discharge pipeline. The long and vertically aligned pores inside the aerogel provide an exceptional flux of 1100 L m-2 h-1, 450% higher than that of the rough and zigzag paths in the isotropic CoFe2O4@graphene hybrid aerogel (CFO@GA-I), and the leaching of metal ions is obviously inhibited by relieving the erosion of CoFe2O4. Besides, the CFO@GA-A could sustain the scour of high-speed flowing wastewater and maintain its structural stability. Therefore, organic contaminants of indigo carmine, methyl orange, orange II, malachite green, phenol, and norfloxacin could readily flow over the nanocatalysts and be degraded rapidly within 7.5-12.5 min at varied flow rates from 60 to 120 mL h-1. The CFO@GA-A also exhibits a much better long-term stability with removal efficiencies toward indigo carmine at 100%, 91%, and 85% for at least 30 h (60 mL h-1), 25 h (90 mL h-1), and 21 h (120 mL h-1), respectively. On the contrary, the CFO@GA-I exhibits unsatisfactory removal efficiencies of <40%. Interestingly, CFO@GA-A could also serve as building blocks to stack on each other for degrading intense flowing wastewater, exhibiting an outstanding composability. The high-flux and long-term stability make the CFO@GA-A promising as an ideal catalytic material for wastewater treatments.
RESUMO
Beclin1, a key regulator of autophagy, has been demonstrated to be associated with cancer cell resistance to chemotherapy. Paclitaxel is a conventional chemotherapeutic drug used in the clinical treatment of breast cancer. However, the function and mechanism of Beclin1 in paclitaxelmediated cytotoxicity in breast cancer are not well defined. The present study demonstrated that paclitaxel suppressed cell viability and Beclin1 expression levels in BT474 breast cancer cells in a dose and timedependent fashion. Compared with the control, the knockdown of Beclin1 significantly enhanced breast cancer cell death via the induction of caspasedependent apoptosis following paclitaxel treatment in vitro (P<0.05). In a BT474 xenograft model, paclitaxel achieved substantial inhibition of tumor growth in the Beclin1 knockdown group compared with the control group. Furthermore, analysis of the publicly available Gene Expression Omnibus datasets revealed a clinical correlation between Beclin1 levels and the response to paclitaxel therapy in patients with breast cancer. Collectively, the present results suggest that Beclin1 protects breast cancer cells from apoptotic death. Thus, the inhibition of Beclin1 may be a novel way to improve the effect of paclitaxel. Additionally, Beclin1 may function as a favorable prognostic biomarker for paclitaxel treatment in patients with breast cancer.
Assuntos
Apoptose/efeitos dos fármacos , Proteína Beclina-1/antagonistas & inibidores , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Paclitaxel/farmacologia , Proteína Beclina-1/metabolismo , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Feminino , Técnicas de Silenciamento de Genes , Humanos , Ensaio Tumoral de Célula-Tronco , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
PURPOSE: With the growing popularity of upper lid blepharoplasty, there have been increasing reports of unsatisfactory outcomes that have necessitated a revision surgery. This study aimed to evaluate aesthetic outcomes of surgical correction of the high eyelid fold using a pretarsal orbicularis oculi flap and to highlight the key practice points of this surgical procedure in secondary blepharoplasty. METHODS: A retrospective study of 31 consecutive Chinese patients who underwent revision surgeries between January 2013 and December 2015 was undertaken through a review of medical records. All these patients underwent surgical correction of high eyelid folds using a pretarsal orbicularis oculi flap, with postoperative follow-up ranging from 6 months to 4 years. Postoperative outcomes were reviewed, evaluated, and analyzed. RESULTS: In this study of 31 women who underwent secondary revision procedure of the high eyelid fold using a pretarsal orbicularis oculi muscle flap, mean follow-up time was 8.2 (range 6-48) months. All flaps survived without significant complications. There was no reported incidence of hematoma or infection in early postoperative complications. Clinical effectiveness was satisfactory in most of the patients who underwent fold repair (26/31, 83.9%). However, five patients (16.1%) expressed dissatisfaction with postoperative outcomes; of them, four patients (12.9%) had mild asymmetry, whereas surgical revision was required in only one patient (3.2%). CONCLUSION: Secondary blepharoplasty to correct the high eyelid fold is a challenging procedure for plastic surgeons. Use of the pretarsal orbicularis oculi muscle flap for correction of the high eyelid fold is safe and effective, with better biomechanics and a satisfying aesthetic outcome. This provides a novel treatment option in limited secondary revision techniques.
Assuntos
Blefaroplastia/métodos , Doenças Palpebrais/cirurgia , Retalhos Cirúrgicos , Adulto , Estética , Músculos Faciais/transplante , Feminino , Humanos , Pessoa de Meia-Idade , Retalho Miocutâneo , Satisfação do Paciente , Reoperação/métodos , Estudos Retrospectivos , Resultado do Tratamento , Adulto JovemRESUMO
BACKGROUND: Partial or total eyebrow defects after trauma or tumor excisions have been repaired by several surgical technique and algorithms. However, these algorithms are often complicated and difficult to apply clinically. We therefore established a simplified surgical algorithm for the treatment of eyebrow defects using flap reconstruction. METHODS: During the period between January 2009 and December 2015, a total of 21 Chinese patients (12 males, 9 females) with eyebrow defects were treated with eyebrow flap reconstruction. The ages ranged from 12 to 51 years. The patients included 13 cases located on the left and 8 cases on the right eyebrow. These defects were caused by trauma (5 patients) and tumor excision (16 patients). Among them, 6 patients were treated using superficial temporal artery island flap, while 15 patients were treated using the V-Y advancement pedicle flap based on the orbicularis oculi muscle. The minimum defect area was 0.8 × 1.0 cm and maximum area was 2.3 × 4.3 cm. All patients were followed up for 6 months to 5 years postoperatively. The clinical effects of eyebrow reconstruction were evaluated using a designated scoring system. RESULTS: All 21 flaps survived without significant complications and the shapes of the reconstructed eyebrows were continuous, symmetrical and with good integrity. According to the rating scale, there were 13 excellent, 8 good reconstructions among all patients. After an average of 9 months of follow-up, all patients had no recurrence of tumors and no infection or scarring. CONCLUSIONS: Based upon our experience with 21 patients who underwent eyebrow reconstruction for various eyebrow defects, we believe that our simplified surgical algorithm can serve as a model for the treatment of patients with eyebrow defects.
Assuntos
Algoritmos , Sobrancelhas , Neoplasias Faciais/cirurgia , Neoplasias Cutâneas/cirurgia , Retalhos Cirúrgicos , Ferimentos e Lesões/cirurgia , Adolescente , Adulto , Criança , Procedimentos Cirúrgicos Dermatológicos/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto JovemRESUMO
OBJECTIVES: Ischemic heart disease (IHD) is a large public health problem and is associated with a number of modifiable risk factors. The aim of this study was to estimate the IHD burden and attributable to risk factors in Fujian, China during 1990 to 2013. METHODS: IHD deaths, disability-adjusted life years (DALYs) and attributable to risk factors were estimated as part of the Global Burden of Disease (GBD) 2013 Study. Statistical models were employed to produce comprehensive results of IHD deaths, DALYs and attributable to risk. Means and 95% uncertainty intervals (UIs) were calculated for mortality and DALYs. The median of the percent change and 95% UI were determined for the period between 1990 and 2013. RESULTS: The age-standardized IHD deaths rate increased by 15.3% from 1990 [74.7 (95% UI 62.9-99.1) per 100,000] to 2013 [82.7 (56.5-95.5) per 100,000]. The age-standardized IHD DALYs has slightly decreased 8.8% from 1990 to 2013[from 1356.2 (1134.3-1732.1) to 1202.7 (879.6-1404.6) per 100,000]. All risks combined account for 94.7% (92.9%- 96.0%) of IHD DALYs for all ages in 2013. The five leading risk factors for all ages IHD DALYs were high systolic blood pressure, high total cholesterol, smoking, diet high in sodium, and high fasting plasma glucose. CONCLUSION: Despite decreased age-standardized IHD deaths and DALY rate since 1990, population growth and aging led to a higher global burden of IHD in 2013. Behavioral, environmental, and metabolic risks can explain most of the IHD DALYs providing many opportunities for prevention.
Assuntos
Isquemia Miocárdica/epidemiologia , Idoso , Idoso de 80 Anos ou mais , China/epidemiologia , Efeitos Psicossociais da Doença , Feminino , Carga Global da Doença , Humanos , Masculino , Pessoa de Meia-Idade , Isquemia Miocárdica/economia , Isquemia Miocárdica/mortalidade , Isquemia Miocárdica/psicologia , Anos de Vida Ajustados por Qualidade de Vida , Fatores de RiscoRESUMO
Colorectal cancer (CRC) is the second most fatal and the third most diagnosed type of cancer worldwide. We sequenced a complete mitochondrial genome sequence of a rat CRC cell line MCA38 for the first time. The total length of the mitogenome was 16,305 bp and coding 13 protein-coding genes, 2 ribosomal RNA genes, 22 transfer RNA genes. This mitochondrial genome sequence will provide new genetic resource into Colon cancer disease.
Assuntos
Neoplasias Colorretais/genética , Genoma Mitocondrial , Animais , Sequência de Bases , Linhagem Celular Tumoral , Genes Mitocondriais , RNA de Transferência/genética , RatosRESUMO
The dengue virus (DENV) envelope protein domain III (ED3) has been suggested to contain receptor recognition sites and the critical neutralizing epitopes. Up to date, relatively little work has been done on fine mapping of neutralizing epitopes on ED3 for DENV4. In this study, a novel mouse type-specific neutralizing antibody 1G6 against DENV4 was obtained with both prophylactic and therapeutic effects. The epitope was mapped to residues 387-390 of DENV4 envelope protein. Furthermore, site-directed mutagenesis assay identified two critical residues (T388 and H390). The epitope is variable among different DENV serotypes but is highly conserved among four DENV4 genotypes. Affinity measurement showed that naturally occurring variations in ED3 outside the epitope region did not alter the binding of mAb 1G6. These findings expand our understanding of the interactions between neutralizing antibodies and the DENV4 and may be valuable for rational design of DENV vaccines and antiviral drugs.
Assuntos
Vírus da Dengue/imunologia , Epitopos/imunologia , Testes de Neutralização , Animais , Linhagem Celular , Cricetinae , Proteínas do Envelope Viral/imunologiaRESUMO
It is an usual clinical phenomenon that cancer patients are prone to thrombosis. Until now, there have been no efficient methods or appropriate drugs to prevent and cure tumor thrombus. Therefore, the construction of a bifunctional chimeric protein for the treatment of cancer, complicated with thrombosis, is of great significance. Utilizing the superantigenic activity of staphylococcal enterotoxin C2 (SEC2) and the thrombolytic activity of staphylokinase (Sak), Sak-linker-SEC2 and SEC2-linker-Sak were constructed which had good anti-tumor and thrombolytic activities at the same time. Due to the intrinsic emetic activity of SEC2 and high molecular weight (MW) of chimeric proteins (44 kDa), their clinical applications will be restricted. In this study, novel chimeric proteins including ΔSEC2-ΔSak and ΔSak-ΔSEC2 were constructed through the truncation of SEC2 and Sak without 9-Ala linker and His-tag. Compared with the former, both the truncated proteins preserved nearly the same anti-tumor and thrombolytic activities. In addition, their MWs were only 29 kDa and their immunoreactivities were slightly lower than that of Sak-linker-SEC2 and SEC2-linker-Sak, respectively. Therefore, the novel chimeric proteins possessed merits and characteristics, such as low MS, low immunogenicity, and difunctionality which the former had not. It will be of great interest if the above-mentioned proteins can be used to cure Trousseau syndrome in clinic.
Assuntos
Enterotoxinas/genética , Metaloendopeptidases/genética , Neoplasias/tratamento farmacológico , Proteínas Recombinantes de Fusão/administração & dosagem , Trombose/tratamento farmacológico , Enterotoxinas/administração & dosagem , Fibrinolíticos/administração & dosagem , Humanos , Metaloendopeptidases/administração & dosagem , Neoplasias/complicações , Neoplasias/genética , Neoplasias/patologia , Engenharia de Proteínas , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genética , Staphylococcus aureus/química , Trombose/complicações , Trombose/genética , Trombose/patologiaRESUMO
4'-Thiosemicarbazonegriseofulvin, a new thiosemicarbazide derivative of griseofulvin, was synthesized and evaluated for its potential in the control of enzymatic browning and postharvest disease of fruits. Browning on fruits is mainly due to the enzymatic oxidation of phenolic compounds catalyzed by tyrosinase. 4'-Thiosemicarbazonegriseofulvin could effectively inhibit the activity of tyrosinase, and its 50% inhibitory concentration (IC(50)) against tyrosinase was determined to be 37.8 µM. It was a reversible and noncompetitive inhibitor of tyrosinase, and its inhibition constant (K(I)) was determined to be 38.42 µM. The antifungal activity of 4'-thiosemicarbazonegriseofulvin was studied against four fungi (Fusarium oxysporum, Fusarium moniliforme, Fusarium solani, and Colletotrichum truncatum) that often cause postharvest diseases of fruits. The results showed that 4'-thiosemicarbazonegriseofulvin could also strongly inhibit the mycelial growth of the four target fungi; the 50% lethal concentration (LC(50)) values were 5.4, 7.0, 15.3, and 1.5 mM, respectively.
Assuntos
Antifúngicos/farmacologia , Inibidores Enzimáticos/farmacologia , Frutas/microbiologia , Griseofulvina/farmacologia , Doenças das Plantas/microbiologia , Proteínas de Plantas/antagonistas & inibidores , Tiossemicarbazonas/farmacologia , Antifúngicos/síntese química , Colletotrichum/efeitos dos fármacos , Colletotrichum/fisiologia , Conservação de Alimentos , Frutas/enzimologia , Fusarium/fisiologia , Griseofulvina/síntese química , Monofenol Mono-Oxigenase/antagonistas & inibidores , Monofenol Mono-Oxigenase/metabolismo , Proteínas de Plantas/metabolismo , Tiossemicarbazonas/síntese químicaRESUMO
The disulfide relay system in the mitochondrial intermembrane space drives the import of proteins with twin CX(9)C or twin CX(3)C motifs by an oxidative folding mechanism. This process requires disulfide bond transfer from oxidized Mia40 to a substrate protein. Reduced Mia40 is reoxidized/regenerated by the FAD-linked sulfhydryl oxidase Erv1 (EC 1.8.3.2). Full-length Erv1 consists of a flexible N-terminal shuttle domain (NTD) and a conserved C-terminal core domain (CTD). Here, we present crystal structures at 2.0 Å resolution of the CTD and at 3.0 Å resolution of a C30S/C133S double mutant of full-length Erv1 (Erv1FL). Similar to previous homologous structures, the CTD exists as a homodimer, with each subunit consisting of a conserved four-helix bundle that accommodates the isoalloxazine ring of FAD and an additional single-turn helix. The structure of Erv1FL enabled us to identify, for the first time, the three-dimensional structure of the Erv1NTD, which is an amphipathic helix flanked by two flexible loops. This structure also represents an intermediate state of electron transfer from the NTD to the CTD of another subunit. Comparative structural analysis revealed that the four-helix bundle of the CTD forms a wide platform for the electron donor NTD. Moreover, computational simulation combined with multiple-sequence alignment suggested that the amphipathic helix close to the shuttle redox enter is critical for the recognition of Mia40, the upstream electron donor. These findings provide structural insights into electron transfer from Mia40 via the shuttle domain of one subunit of Erv1 to the CTD of another Erv1 subunit.
Assuntos
Mitocôndrias/enzimologia , Proteínas Mitocondriais/química , Oxirredutases atuantes sobre Doadores de Grupo Enxofre/química , Proteínas de Saccharomyces cerevisiae/química , Saccharomyces cerevisiae/enzimologia , Motivos de Aminoácidos , Substituição de Aminoácidos , Cristalografia por Raios X , Dissulfetos/química , Dissulfetos/metabolismo , Transporte de Elétrons/fisiologia , Mitocôndrias/genética , Proteínas de Transporte da Membrana Mitocondrial/química , Proteínas de Transporte da Membrana Mitocondrial/genética , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Proteínas do Complexo de Importação de Proteína Precursora Mitocondrial , Proteínas Mitocondriais/genética , Proteínas Mitocondriais/metabolismo , Mutação de Sentido Incorreto , Oxirredutases atuantes sobre Doadores de Grupo Enxofre/genética , Oxirredutases atuantes sobre Doadores de Grupo Enxofre/metabolismo , Dobramento de Proteína , Estrutura Terciária de Proteína , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismoRESUMO
Peroxiredoxins (Prxs) are thiol-specific antioxidant proteins that protect cells against reactive oxygen species and are involved in cellular signaling pathways. Alkyl hydroperoxide reductase Ahp1 belongs to the Prx5 subfamily and is a two-cysteine (2-Cys) Prx that forms an intermolecular disulfide bond. Enzymatic assays and bioinformatics enabled us to re-assign the peroxidatic cysteine (C(P)) to Cys-62 and the resolving cysteine (C(R)) to Cys-31 but not the previously reported Cys-120. Thus Ahp1 represents the first 2-Cys Prx with a peroxidatic cysteine after the resolving cysteine in the primary sequence. We also found the positive cooperativity of the substrate t-butyl hydroperoxide binding to Ahp1 homodimer at a Hill coefficient of â¼2, which enabled Ahp1 to eliminate hydroperoxide at much higher efficiency. To gain the structural insights into the catalytic cycle of Ahp1, we determined the crystal structures of Ahp1 in the oxidized, reduced, and Trx2-complexed forms at 2.40, 2.91, and 2.10 Å resolution, respectively. Structural superposition of the oxidized to the reduced form revealed significant conformational changes at the segments containing C(P) and C(R). An intermolecular C(P)-C(R) disulfide bond crossing the A-type dimer interface distinguishes Ahp1 from other typical 2-Cys Prxs. The structure of the Ahp1-Trx2 complex showed for the first time how the electron transfers from thioredoxin to a peroxidase with a thioredoxin-like fold. In addition, site-directed mutagenesis in combination with enzymatic assays suggested that the peroxidase activity of Ahp1 would be altered upon the urmylation (covalently conjugated to ubiquitin-related modifier Urm1) of Lys-32.
Assuntos
Cisteína/química , Complexos Multienzimáticos/química , Peroxirredoxinas/química , Espécies Reativas de Oxigênio/química , Proteínas de Saccharomyces cerevisiae/química , Saccharomyces cerevisiae/enzimologia , Tiorredoxinas/química , Sítios de Ligação , Cristalografia por Raios X , Cisteína/metabolismo , Transporte de Elétrons/fisiologia , Complexos Multienzimáticos/genética , Complexos Multienzimáticos/metabolismo , Oxirredução , Peroxirredoxinas/genética , Peroxirredoxinas/metabolismo , Multimerização Proteica , Estrutura Quaternária de Proteína , Espécies Reativas de Oxigênio/metabolismo , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Tiorredoxinas/genética , Tiorredoxinas/metabolismo , terc-Butil Hidroperóxido/químicaRESUMO
In insects, tyrosinase plays important roles in normal developmental processes, such as cuticular tanning, scleration, wound healing, production of opsonins, encapsulation and nodule formation for defense against foreign pathogens. Thus, tyrosinase may be regarded as a potential candidate for novel bioinsecticide development. A family of alkyl 3,4-dihydroxybenzoates (C6-C9), new tyrosinsase inhibitors, were synthesized. Their inhibitory effects on the activity of tyrosinase have been investigated. The results showed all of them could inhibit the activity of tyrosianse effectively. The order of potency was nonyl 3,4-dihydroxybenzoate (C9DB) > octyl 3,4-dihydroxybenzoate(C8DB) > heptyl 3,4-dihydroxybenzoate(C7DB) > hexyl 3,4-dihydroxybenzoate (C6DB). The kinetic analysis of these four compounds on tyrosinase was taken to expound their inhibitory mechanism. The research of the control of insects in agriculture was taken as C6DB for example. C6DB could inhibit the development and molting of Plutella xylostella effectively. To clarify its insecticidal mechanism, we researched the expression of tyrosinase in the P. xylostella treated with C6DB by real-time quantitative PCR. The results showed C6DB could inhibit the expression of tyrosinase in the P. xylostella as expected.
Assuntos
Inibidores Enzimáticos/química , Hidroxibenzoatos/química , Controle de Insetos/métodos , Proteínas de Insetos/antagonistas & inibidores , Monofenol Mono-Oxigenase/antagonistas & inibidores , Mariposas/enzimologia , Controle Biológico de Vetores/métodos , Animais , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/farmacologia , Hidroxibenzoatos/síntese química , Hidroxibenzoatos/farmacologia , Cinética , Mariposas/efeitos dos fármacosRESUMO
2-Chlorobenzaldehyde thiosemicarbazone (2-Cl-BT) and 4-chlorobenzaldehyde thiosemicarbazone (4-Cl-BT) were synthesized, and their inhibitory kinetics on the activity of mushroom tyrosinase were investigated. Results showed that these compounds exhibited significant inhibitory potency on both monophenolase activity and diphenolase activity of tyrosinase. For the monophenolase activity, both compounds could decrease the steady-state activity of the enzyme sharply, without any influence on the lag period. The IC50 values of them were estimated to be 15.4 µM and 6.7 µM, respectively. For the diphenolase activity, both compounds belonged to reversible inhibitors, but their mechanisms were different: 2-Cl-BT was a noncompetitive type inhibitor, while 4-Cl-BT was a mixed-type inhibitor. Their inhibition constants were determined and compared.