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Proteomic analysis of the proteolytic activity of HF3, a metalloproteinase from the venom of Bothrops jararaca, upon human and snake plasma

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Luciana Bertholim Nasciben
Total Authors: 1
Document type: Master's Dissertation
Press: São Paulo.
Institution: Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ)
Defense date:
Examining board members:
Solange Maria de Toledo Serrano; Maria Teresa Machini; Ana Maria Moura da Silva
Advisor: Solange Maria de Toledo Serrano

Hemorrhage induced by snake venom metalloproteinases is a complex phenomenon resulting in capillary disruption and blood extravasation. HF3 (hemorrhagic factor 3) is an extremely hemorrhagic, P-IIIa class metalloproteinase, isolated from the venom of Bothrops jararaca. The analysis of its proteolytic activity on isolated proteins showed that plasma and extracellular matrix proteins are hydrolyzed by HF3. Studies using proteomic approaches to analyze the effects of HF3 in the mouse skin and plasma showed new targets of this metalloproteinase, including intracellular, extracellular and plasma proteins. However, the mechanisms involved in the hemorrhagic process generated by HF3, particularly the role of the cleavage of plasma proteins in the context of the hemorrhage, remain not fully understood. Thus, the main objective of this study was to analyze the degradome of HF3 in human plasma. In parallel, we also carried out the analysis of the activity of HF3 on B. jararaca plasma. For this purpose, approaches for the depletion of the most abundant proteins and for the enrichment of low abundant proteins of the human plasma were used to minimize the dynamic range of protein concentration, in order to assess the proteolytic activity HF3 on a wide spectrum of proteins, and to detect the degradation products by mass spectrometry. Thus, four samples of human plasma were used in this study: whole plasma, albumin-depleted plasma, plasma depleted of the 20 most abundant proteins, and plasma enriched of low abundance proteins. Incubation of these samples with HF3 was carried out at a 1:100 (w/w) enzyme-to-substrate ratio, for 2 h, at 37°C. After the incubation time, the protein and peptide fractions were analyzed. The identification of peptides present in the plasma peptide fraction by mass spectrometry revealed the products from the hydrolysis of proteins by HF3 and allowed the analysis of the cleavage sites. The effect of HF3 on the sample of plasma enriched of low-abundance proteins was also analyzed by SDS-polyacrylamide gel electrophoresis followed by in gel protein digestion with trypsin of differential bands and identification by mass spectrometry. Considering all the approaches used in this study, 62 plasma proteins were identified as cleaved by HF3. Some of these proteins corroborate previous studies and others are considered as substrate candidates of HF3. Among the new targets, there are proteins of the coagulation cascade and of the complement system, as well as plasma proteinase inhibitors, suggesting that this metalloproteinase escapes inhibition and may act in an unregulated fashion causing the imbalance of hemostasis. The activity of HF3 on B. jararaca plasma proteins was analyzed by its incubation with whole plasma, as described above, and resulted in the generation of a low number of peptides, which, however, did not result in the identification of any substrate by mass spectrometry. Taken together, our data confirm previous findings on the repertoire of substrates of HF3 in the human plasma and suggest new substrate candidates that may contribute to the understanding of the hemorrhagic effect of HF3. (AU)

FAPESP's process: 11/16623-1 - Proteomic analysis of the proteolytic activity of HF3, a metalloproteinase from the venom of Bothrops jararaca, upon human and snake plasma.
Grantee:Luciana Bertholim Nasciben
Support Opportunities: Scholarships in Brazil - Master