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1.
Health Soc Care Community ; 29(1): 194-205, 2021 01.
Article in English | MEDLINE | ID: mdl-32681607

ABSTRACT

The aim of this study was to assess the public's opinions and expectations of self-medication consultations in German community pharmacies with special emphasis on the acceptance of guideline-recommended consultation. In a cross-sectional study in the city centre of Leipzig, Germany, we conducted a questionnaire-based survey administered via an interview with passers-by from June to September 2018. The structured questionnaire contained questions assessing (I) previous experience with self-medication consultations, (II) possible reasons for declining self-medication consultations, (III) the attitude towards information gathering and (IV) expectations of self-medication consultations. (I) 92% of the 963 respondents stated they were generally satisfied with self-medication consultations in community pharmacies. Around one-fifth of all respondents claimed that they would like to be asked more health-related questions (22%) and receive more information on non-prescription drugs (20%). (II) Privacy issues (39%) and reluctance to talk about some medical conditions (43%) were the most frequent reasons for declining self-medication consultation. (III) Respondents understood the need for answering guideline-recommended questions (85-96%) and did not mind being asked these questions (70-96%). (IV) Most of the respondents expected to be counselled even if they did not ask for it directly (69%). Pharmacies were further expected to recommend the best drug, even if it was not what the customer initially intended to buy (87%). However, more than half of the respondents would consider counselling as unimportant if they knew exactly which medication they wanted to buy (56%) or if they had used the non-prescription drug before (70%). The majority also expected to receive guideline-recommended drug information (each item at least 52%). Thus, our study shows that respondents were mostly in line with the required standards of self-medication counselling guidelines. Customers expect high-quality counselling on self-medication. These findings support pharmaceutical staff's understanding of customers' barriers and expectations during self-medication consultations.


Subject(s)
Pharmacies , Cross-Sectional Studies , Humans , Nonprescription Drugs , Pharmacists , Referral and Consultation , Self Medication , Surveys and Questionnaires
2.
Toxicon ; 184: 68-77, 2020 Sep.
Article in English | MEDLINE | ID: mdl-32526239

ABSTRACT

Cobra venom factor (CVF) is the complement-activating protein in cobra venom. CVF is a structural and functional analog of complement component C3. CVF, like C3b, forms a convertase with factor B. This bimolecular complex CVF, Bb is an enzyme that cleaves C3 and C5. However, CVF, Bb exhibits significantly different functional properties from C3b,Bb. Whereas both, CVF, Bb and C3b, Bb exhibit spontaneous decay-dissociation into the respective subunits, thereby eliminating the enzymatic activity, the CVF, Bb convertase is physico-chemically far more stable, decaying with a half-life that is more than two orders of magnitude slower than that of C3b,Bb. In addition, CVF, Bb is completely resistant to inactivation by Factors H and I. These two properties of CVF, Bb allow continuous activation of C3 and C5, and complement depletion in serum. In order to understand the structural basis for the physico-chemical stability of CVF,Bb, we have created recombinant hybrid proteins of CVF and human C3, based on structural differences between CVF and human C3b in the C-terminal C345C domain. Here we describe three human C3/CVF hybrid proteins which differ in only one, two, or five amino acid residues from earlier described hybrid proteins. In all three cases, the hybrid proteins containing CVF residues form more stable convertases, and exhibit stronger complement-depletion activity than hybrid proteins with human C3 residues. Three bonds between CVF residues and Factor Bb residues could be identified by crystallographic modeling that contribute to the greater stability of the convertases.


Subject(s)
Complement C3-C5 Convertases/chemistry , Complement Factor B/chemistry , Elapid Venoms/chemistry , Animals , Complement C3 , Complement Factor H , Humans , Recombinant Fusion Proteins
3.
JCO Glob Oncol ; 6: 155-160, 2020 02.
Article in English | MEDLINE | ID: mdl-32031449

ABSTRACT

Sociocultural, geographic, and biologic factors contribute to cancer health disparities (CHDs) in indigenous Pacific peoples (IPPs) in Guam, Hawai'i, and the US Associated Pacific Islands (USAPI). IPPs experience a greater burden of CHDs that are associated with late-stage diagnosis and poor survival outcomes compared with majority populations in the United States. A 16-year partnership between the University of Guam (UOG) and University of Hawai'i Cancer Center (UHCC) aims to advance health equity in Guam, Hawai'i, and the USAPI through cancer research, training, and outreach. Investigators at collaborating institutions study issues of regional and cultural relevance in IPPs, including breast, cervical, liver, and oral cancers and use of tobacco and betel nuts (Areca nuts). Junior faculty with IPP ancestry or those who are focused on CHDs in IPPs receive mentorship and career development opportunities, academic fellowships are provided for graduate students, and Pacific Island communities are engaged through a participatory development process. The partnership has generated more than 90 peer-reviewed publications, more than 100 abstracts, and 11 grant awards. Thirty graduate scholars from under-represented minorities have been trained, including two who are now UOG faculty and are conducting independent research, contributing to the partnership, and mentoring scientists of tomorrow. Participatory community engagement has contributed to the passage of significant cancer prevention and control legislation in Hawai'i, Guam, and Saipan. Research capacity at UOG has increased significantly, and research at UHCC has expanded to address issues unique to IPPs. Graduate students from under-represented minorities are pursuing careers in cancer research. A regional research infrastructure has been established to support team science, and research findings are informing public health policy and planning.


Subject(s)
Capacity Building , Mouth Neoplasms , Guam , Hawaii/epidemiology , Humans , Pacific Islands/epidemiology , United States/epidemiology
4.
Front Cell Dev Biol ; 8: 606407, 2020.
Article in English | MEDLINE | ID: mdl-33425913

ABSTRACT

This article reviews the pathogenetic role of the complement system in myocardial infarction reperfusion injury. The complement activation pathways involved in myocardial tissue injury are identified, as are the complement-derived effector molecules. The results of past anti-complement therapies are reviewed; as the more recent therapeutic concept of complement depletion with humanized CVF described.

5.
Mar Drugs ; 17(8)2019 Jul 25.
Article in English | MEDLINE | ID: mdl-31349625

ABSTRACT

Breast cancer is the most common cancer type and a primary cause of cancer mortality among females worldwide. Here, we analyzed the anticancer efficacy of a novel bromochlorinated monoterpene, PPM1, a synthetic analogue of polyhalogenated monoterpenes from Plocamium red algae and structurally similar non-brominated monoterpenes. PPM1, but not the non-brominated monoterpenes, decreased selectively the viability of several triple-negative as well as triple-positive breast cancer cells with different p53 status without significantly affecting normal breast epithelial cells. PPM1 induced accumulation of triple-negative MDA-MB-231 cells with 4N DNA content characterized by decreased histone H3-S10/T3 phosphorylation indicating cell cycle arrest in the G2 phase. Western immunoblot analysis revealed that PPM1 treatment triggered an initial rapid activation of Aurora kinases A/B/C and p21Waf1/Cip1 accumulation, which was followed by accumulation of polyploid >4N cells. Flow cytometric analysis showed mitochondrial potential disruption, caspase 3/7 activation, phosphatidylserine externalization, reduction of the amount polyploid cells, and DNA fragmentation consistent with induction of apoptosis. Cell viability was partially restored by the pan-caspase inhibitor Z-VAD-FMK indicating caspase contribution. In vivo, PPM1 inhibited growth, proliferation, and induced apoptosis in MDA-MB-231 xenografted onto the chick chorioallantoic membrane. Hence, Plocamium polyhalogenated monoterpenes and synthetic analogues deserve further exploration as promising anticancer lead compounds.


Subject(s)
Apoptosis/drug effects , Breast Neoplasms/drug therapy , Cell Cycle Checkpoints/drug effects , Monoterpenes/pharmacology , Antineoplastic Agents/pharmacology , Breast/drug effects , Breast/metabolism , Breast Neoplasms/metabolism , Caspase Inhibitors/pharmacology , Caspases/metabolism , Cell Line, Tumor , Cell Proliferation/drug effects , Cell Survival/drug effects , Epithelial Cells/drug effects , Epithelial Cells/metabolism , Female , G2 Phase/drug effects , Histones/metabolism , Humans , MCF-7 Cells , Mitochondria/drug effects , Mitochondria/metabolism , Plocamium/chemistry , Rhodophyta/chemistry
6.
Hawaii J Med Public Health ; 78(6): 205-207, 2019 06.
Article in English | MEDLINE | ID: mdl-31205817

ABSTRACT

This manuscript describes the efforts in research, education, and outreach of a unique partnership between the University of Hawai'i Cancer Center and the University of Guam in addressing cancer health disparities faced by Pacific Islanders in Hawai'i, Guam, and other parts of Micronesia. Significant accomplishments of this 15-year collaboration in research, training Micronesian students, and impact on the local communities are highlighted.


Subject(s)
Biomedical Research , Cancer Care Facilities , Healthcare Disparities , Native Hawaiian or Other Pacific Islander/ethnology , Neoplasms/etiology , Universities , Biomedical Research/education , Cooperative Behavior , Early Detection of Cancer , Guam , Hawaii , Health Education , Humans , Neoplasms/diagnosis , Neoplasms/prevention & control
7.
Toxicon ; 167: 106-116, 2019 Sep.
Article in English | MEDLINE | ID: mdl-31207349

ABSTRACT

Cobra venom factor (CVF) is the complement-activating protein in cobra venom. CVF is a structural and functional analog of complement component C3. CVF, like C3b, forms a convertase with factor B. This bimolecular complex CVF,Bb is an enzyme that cleaves C3 and C5. However, CVF,Bb exhibits significantly different functional properties from C3b,Bb. The CVF,Bb convertase is physico-chemically very stable, and completely resistant to an activation by Factors H and I. These two properties, in contrast to C3b,Bb, allow continuous activation of C3 and C5, and complement depletion in serum. In order to understand the structural basis for the functional differences between CVF and C3, we have created several hybrid proteins of CVF and human C3. Here we report that replacing the C-terminal 168 amino acid residues of human C3 with the corresponding residues from CVF results in a hybrid protein (HC3-1496) which is essentially a human C3 derivative exhibiting the functional properties of CVF. This result demonstrates that the important structures for the CVF-specific functions reside within the C-terminal 168 amino acid residues of CVF. We further demonstrate that reverting the 46 C-terminal CVF residues of HC3-1496 to human C3 sequence results in a hybrid protein (HC3-1496/1617) that exhibits a physico-chemically unstable convertase with only residual complement depleting activity. This result demonstrates that most, but not all, structural requirements for CVF activity reside within the 46 C-terminal amino acid residues. We also investigated the potential role of position 1633, which is an acidic residue in human C3 (glutamic acid) but a basic amino acid residue (histidine) in CVF. However, the charge at position 1633 appears to be of no functional relevance. Exchanging the neutral amino acids present in CVF at positions 1499 and 1501 with the two charged amino acids at these positions in human C3 (aspartic acid and lysine) resulted in a hybrid protein that exhibited significantly slower convertase formation although both binding to Factor B and C3 cleavage was not affected, demonstrating that the charged amino acid residues at these two positions interfere with the formation of the convertase. In conclusion, our work demonstrates that hybrid proteins of human C3 and CVF present valuable tools to identify functionally important amino acid residues in CVF.


Subject(s)
Complement C3/chemistry , Elapid Venoms/chemistry , Amino Acid Sequence , Humans , Recombinant Fusion Proteins/chemistry , Sequence Analysis, Protein , Structure-Activity Relationship
9.
Mol Immunol ; 97: 1-7, 2018 05.
Article in English | MEDLINE | ID: mdl-29525557

ABSTRACT

Cobra venom factor (CVF) is the complement-activating protein in cobra venom. Humanized CVF (hCVF) is a human C3 derivative where the C-terminal 168 amino acid residues were replaced with the homologous sequence from CVF. hCVF has been shown in multiple models of disease with complement pathology to be a promising therapeutic agent, with no observed adverse effects. Here we describe the antibody response to hCVF in two different strains of mice. hCVF was able to repeatedly decomplement the mice after four injections in weekly intervals, demonstrating the absence of a neutralizing antibody response. In contrast, natural CVF caused decomplementation in all mice only after the first administration. After two additional administrations of natural CVF, decomplementation was inconsistent and varied tremendously from mouse to mouse. After the fourth administration, natural CVF was essentially unable to deplete complement, consistent with the known generation of a neutralizing antibody response. We also analyzed the IgG antibody response to hCVF. There was great variation, with approximately one quarter of the mice exhibiting non-detectable levels of anti-hCVF IgG, and another quarter very low levels. The levels of anti-hCVF IgG did not correlate with the levels of remaining C3. The anti-hCVF antibodies cross-reacted with natural CVF, recombinant CVF, and human C3. Whereas overall the level of anti-hCVF IgG cross-reacting with human C3 was lower compared to rCVF or nCVF, mice with higher levels of anti-hCVF IgG exhibited higher binding to CVF and human C3, excluding the possibility that higher antibody levels reflect preferential immunogenicity of CVF-specific or human C3-specific epitopes.


Subject(s)
Antibodies, Neutralizing/metabolism , Antibody Formation , Elapid Venoms/immunology , Recombinant Fusion Proteins/immunology , Animals , Antibodies, Neutralizing/immunology , CHO Cells , Cells, Cultured , Cricetinae , Cricetulus , Drosophila melanogaster , Elapid Venoms/chemistry , Humans , Mice , Mice, Inbred C57BL , Recombinant Fusion Proteins/chemistry
10.
Haematologica ; 103(2): 351-360, 2018 02.
Article in English | MEDLINE | ID: mdl-29146705

ABSTRACT

Development of neutralizing antibodies against therapeutic Factor VIII (FVIII) is the most serious complication of the treatment of hemophilia A. There is growing evidence to show the multifactorial origin of the anti-FVIII immune response, combining both genetic and environmental factors. While a role for the complement system on innate as well as adaptive immunity has been documented, the implication of complement activation on the onset of the anti-FVIII immune response is unknown. Here, using in vitro assays for FVIII endocytosis by human monocyte-derived dendritic cells and presentation to T cells, as well as in vivo complement depletion in FVIII-deficient mice, we show a novel role for complement C3 in enhancing the immune response against therapeutic FVIII. In vitro, complement C3 and its cleavage product C3b enhanced FVIII endocytosis by dendritic cells and presentation to a FVIII-specific CD4+ T-cell hybridoma. The C1 domain of FVIII had previously been shown to play an important role in FVIII endocytosis, and alanine substitutions of the K2092, F2093 and R2090 C1 residues drastically reduce FVIII uptake in vitro Interestingly, complement activation rescued the endocytosis of the FVIII C1 domain triple mutant. In a mouse model of severe hemophilia A, transient complement C3 depletion by humanized cobra venom factor, which does not generate anaphylatoxin C5a, significantly reduced the primary anti-FVIII immune response, but did not affect anti-FVIII recall immune responses. Taken together, our results suggest an important adjuvant role for the complement cascade in the initiation of the immune response to therapeutic FVIII.


Subject(s)
Antibodies, Neutralizing/immunology , Complement C3/pharmacology , Factor VIII/immunology , Animals , Antigen Presentation/immunology , Complement Activation , Dendritic Cells/physiology , Endocytosis/drug effects , Humans , Immunity/drug effects , Mice
11.
Basic Res Cardiol ; 111(6): 69, 2016 11.
Article in English | MEDLINE | ID: mdl-27743118

ABSTRACT

In this meeting report, particularly addressing the topic of protection of the cardiovascular system from ischemia/reperfusion injury, highlights are presented that relate to conditioning strategies of the heart with respect to molecular mechanisms and outcome in patients' cohorts, the influence of co-morbidities and medications, as well as the contribution of innate immune reactions in cardioprotection. Moreover, developmental or systems biology approaches bear great potential in systematically uncovering unexpected components involved in ischemia-reperfusion injury or heart regeneration. Based on the characterization of particular platelet integrins, mitochondrial redox-linked proteins, or lipid-diol compounds in cardiovascular diseases, their targeting by newly developed theranostics and technologies opens new avenues for diagnosis and therapy of myocardial infarction to improve the patients' outcome.


Subject(s)
Cardiology/trends , Cardiovascular Diseases , Theranostic Nanomedicine/trends , Animals , Cardiology/methods , Humans
12.
PLoS One ; 11(2): e0148257, 2016.
Article in English | MEDLINE | ID: mdl-26886730

ABSTRACT

Using matching and regression analyses, we measure the difference in citations between articles posted to Academia.edu and other articles from similar journals, controlling for field, impact factor, and other variables. Based on a sample size of 31,216 papers, we find that a paper in a median impact factor journal uploaded to Academia.edu receives 16% more citations after one year than a similar article not available online, 51% more citations after three years, and 69% after five years. We also found that articles also posted to Academia.edu had 58% more citations than articles only posted to other online venues, such as personal and departmental home pages, after five years.


Subject(s)
Access to Information , Internet , Periodicals as Topic , Journal Impact Factor , Regression Analysis , Sample Size
13.
Basic Res Cardiol ; 111(1): 7, 2016 Jan.
Article in English | MEDLINE | ID: mdl-26667317

ABSTRACT

Recent advances in basic cardiovascular research as well as their translation into the clinical situation were the focus at the last "New Frontiers in Cardiovascular Research meeting". Major topics included the characterization of new targets and procedures in cardioprotection, deciphering new players and inflammatory mechanisms in ischemic heart disease as well as uncovering microRNAs and other biomarkers as versatile and possibly causal factors in cardiovascular pathogenesis. Although a number of pathological situations such as ischemia-reperfusion injury or atherosclerosis can be simulated and manipulated in diverse animal models, also to challenge new drugs for intervention, patient studies are the ultimate litmus test to obtain unequivocal information about the validity of biomedical concepts and their application in the clinics. Thus, the open and bidirectional exchange between bench and bedside is crucial to advance the field of ischemic heart disease with a particular emphasis of understanding long-lasting approaches in cardioprotection.


Subject(s)
Cardiovascular Diseases , Translational Research, Biomedical , Animals , Humans
14.
Thromb Haemost ; 113(3): 548-52, 2015 Mar.
Article in English | MEDLINE | ID: mdl-25031089

ABSTRACT

The complement system is an intrinsic part of the immune system and has important functions in both innate and adaptive immunity. On the other hand, inadvertent or misdirected complement activation is also involved in the pathogenesis of many diseases, contributing solely or significantly to tissue injury and disease development. Multiple approaches to develop pharmacological agents to inhibit complement are currently being pursued. We have developed a conceptually different approach of not inhibiting but depleting complement, based on the complement-depleting activities of cobra venom factor (CVF), a non-toxic cobra venom component with structural and functional homology to complement component C3. We developed a humanised version of CVF by creating human complement component C3 derivatives with complement-depleting activities of CVF (humanised CVF) as a promising therapeutic agent for diseases with complement pathogenesis. Here we review the beneficial therapeutic effect of humanised CVF in several murine models of vascular diseases such as reperfusion injury.


Subject(s)
Complement Activation/drug effects , Complement C3/pharmacology , Complement Inactivating Agents/pharmacology , Complement System Proteins/metabolism , Elapid Venoms/pharmacology , Immunologic Factors/pharmacology , Reperfusion Injury/drug therapy , Ventilator-Induced Lung Injury/drug therapy , Animals , Complement System Proteins/immunology , Disease Models, Animal , Humans , Recombinant Fusion Proteins/pharmacology , Reperfusion Injury/immunology , Ventilator-Induced Lung Injury/immunology
15.
Angew Chem Int Ed Engl ; 53(45): 12205-9, 2014 Nov 03.
Article in English | MEDLINE | ID: mdl-25220828

ABSTRACT

The family of polyhalogenated monoterpenes from Plocamium counts over a hundred known members. Using glyceraldehyde acetonide as a chiral-pool precursor, an enantioselective and divergent strategy was developed that provides a blueprint for the synthesis of many of the small yet complex acyclic members of this family. The broad applicability of this approach is demonstrated with the short, eight-step synthesis of four natural products and three analogues. These syntheses are the first of any members of the acyclic polyhalogenated Plocamium monoterpenes and permitted the evaluation of their selectivity against a range of tumor cell lines.


Subject(s)
Monoterpenes/chemical synthesis , Neoplasms/drug therapy , Plocamium/chemistry , HCT116 Cells , Humans , Monoterpenes/therapeutic use , Stereoisomerism
16.
Mol Immunol ; 61(2): 191-203, 2014 Oct.
Article in English | MEDLINE | ID: mdl-25062833

ABSTRACT

The complement system is an integral component of both innate and adaptive immunity. However, complement is also a pathogenetic factor in many diseases. The development of agents for therapeutic complement inhibition is the topic of intense investigations by many investigators. We have developed a distinctly different therapeutic approach: complement depletion rather than inhibition. This approach is based on cobra venom factor (CVF), a C3 analog known to be able to safely deplete complement. This manuscript will briefly review the structure and activity of CVF, along with its similarities and differences to C3. Exploiting the knowledge of the structure/function relationship of CVF and C3, we created derivatives of human C3 which display the CVF-like activity of depleting complement, referred to as humanized CVF (hCVF). This review describes the structure and activity of hCVF, including the important property of not cleaving C5. The efficacy of hCVF for therapeutic complement depletion in nine preclinical models diseases with complement pathology is reviewed, including reperfusion injury, age-related macular degeneration (AMD), paroxysmal nocturnal hemoglobinuria (PNH), and immunogenicity of Factor VIII in hemophilia A. Complement depletion is characterized by the absence of toxicity, even after intra-arterial injection into the pulmonary artery of primates. No immunogenicity has been observed.


Subject(s)
Elapid Venoms/chemistry , Elapid Venoms/pharmacology , Recombinant Fusion Proteins , Animals , Complement Inactivating Agents/chemistry , Complement Inactivating Agents/pharmacology , Complement Inactivating Agents/therapeutic use , Drug Evaluation, Preclinical , Elapid Venoms/therapeutic use , Humans
19.
J Eval Clin Pract ; 18(6): 1226-34, 2012 Dec.
Article in English | MEDLINE | ID: mdl-22816797

ABSTRACT

BACKGROUND: The Patient Journey Record system (PaJR) is an application of a complex adaptive chronic care model in which early detection of adverse changes in patient biopsychosocial trajectories prompts tailored care, constitute the cornerstone of the model. AIMS: To evaluate the PaJR system's impact on care and the experiences of older people with chronic illness, who were at risk of repeat admissions over 12 months. DESIGN: Community-based cohort study - random assignment into intervention and usual care group, with process and outcome evaluation. STUDY POPULATION: Adult and older patients with multiple morbidity, one or more chronic diseases with one or more overnight hospitalizations, and seven or more general practice visits in the past 6 months. COMPLEX INTERVENTION: PaJR lay care guides/advocates call patients and their caregivers. The care guides summarize their semi-structured conversations about health concerns and well-being. Predictive modelling and rules-based algorithms trigger alerts in relation to online call summaries. Alerts are acted upon according to agreed guidelines. ANALYSIS: Descriptive and comparative statistics. OUTCOMES: Impact on unplanned emergency ambulatory care sensitive admissions (ACSC) with an overnight stay; sensitivity of alerts and predictions; rates of care guides-supported activities. FINDINGS: Five part-time lay care guides and a care manager monitored 153 intervention patients for 500 person months with 5050 phone calls. The 153 patients in the intervention group were comparable to the 61 controls. The intervention group reported in 50% of calls that their health limited their social activities; and one-third of calls reported immediate health concerns. Predictive analytics were highly sensitive to risk of hospitalization. ACSC admissions were reduced by 50% compared to controls across the sites. DISCUSSION: The initial implementation of a complex patient-centred adaptive chronic care model using lay care guides, supported by machine learning, appeared sensitive to risk of hospitalization and capable of stabilizing illness journeys in older patients with multi-morbidity. CONCLUSION: Actions based on alerts produced in this study appeared to significantly reduce hospitalizations. This paves the way for further testing of the model.


Subject(s)
Chronic Disease/therapy , Disease Management , Health Services/statistics & numerical data , Aged , Aged, 80 and over , Algorithms , Artificial Intelligence , Clinical Protocols , Cohort Studies , Emergency Service, Hospital/statistics & numerical data , Environment , Female , Health Promotion , Health Status , Humans , Male , Middle Aged , Social Support
20.
Toxicon ; 60(4): 632-47, 2012 Sep 15.
Article in English | MEDLINE | ID: mdl-22609532

ABSTRACT

Cobra Venom Factor (CVF) is the complement-activating protein in cobra venom. CVF is structurally and functionally highly homologous to complement component C3. CVF, like C3b, the activated form of C3, forms a bimolecular complex with Factor B in serum, called C3/C5 convertase, an enzyme which activates complement components C3 and C5. Despite the high degree of homology, the two C3/C5 convertases exhibit significant functional differences. The most important difference is that the convertase formed with CVF (CVF,Bb) is physico-chemically far more stable than the convertase formed with C3b (C3b,Bb). In addition, the CVF,Bb convertase and CVF are completely resistant to inactivation by the complement regulatory proteins Factor H and Factor I. Furthermore, the CVF,Bb enzyme shows efficient C5-cleaving activity in fluid phase. In contrast, the C3b,Bb enzyme is essentially devoid of fluid-phase C5-cleaving activity. By taking advantage of the high degree of sequence identity at both the amino acid (85%) and DNA levels (93%) between CVF and cobra C3, we created hybrid proteins of CVF and cobra C3 where sections, or only a few amino acids, of the CVF sequence were replaced with the homologous amino acid sequence of cobra C3. In a first set of experiments, we created five hybrid proteins, termed H1 through H5, where the cobra C3 substitutions collectively spanned the entire length of the CVF protein. We also created three additional hybrid proteins where only four or five amino acid residues in CVF were exchanged with the corresponding amino acid residues from cobra C3. Collectively, these hybrid proteins, representing loss-of-function mutants of CVF, allowed the identification of regions and individual amino acid residues important for the CVF-specific functions. The results include the observation that the CVF ß-chain is crucially important for forming a stable convertase, whereas the CVF α-chain appears to harbor no CVF-specific functions. Furthermore, the CVF γ-chain is additionally important for the fluid-phase C5-cleaving activity of CVF,Bb. Interestingly, the structural changes in the individual hybrid proteins differentially affected the molecular functions of the CVF,Bb enzyme such as convertase formation, C3 cleavage, and C5 cleavage.


Subject(s)
Complement C3/chemistry , Elapid Venoms/chemistry , Recombinant Fusion Proteins/chemistry , Amino Acid Sequence , Amino Acid Substitution , Animals , Complement Activation , Complement C3/genetics , Complement C3-C5 Convertases/metabolism , Complement Factor D/chemistry , Elapid Venoms/genetics , Elapidae/physiology , Enzyme Stability , Humans , Molecular Sequence Data , Mutation, Missense , Plasmids/biosynthesis , Plasmids/genetics , Protein Structure, Tertiary , Recombinant Fusion Proteins/genetics
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