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Crystal structure and activating effect on RyRs of AhV_TL-I, a glycosylated thrombin-like enzyme from Agkistrodon halys snake venom.
MedLine Citation:
PMID:  23052203     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
A snake venom thrombin-like enzyme (SVTLE) from Agkistrodon halys pallas venom was isolated by means of a two-step chromatographic procedure. The purified enzyme, named AhV_TL-I, showed fibrinogenolytic activity against both the Aα and Bβ chains of bovine fibrinogen. Unlike the other SVTLEs, AhV_TL-I has poor esterolytic activity upon BAEE substrate. The N-terminal sequence of AhV_TL-I was determined to be IIGGDEXNINEHRFLVALYT, and the molecular mass was confirmed to 29389.533 Da by MALDI-TOF mass spectrometry. Its complete cDNA and derived amino acid sequence were obtained by RT-PCR. The crystal structure of AhV_TL-I was determined at a resolution of 1.75 Å. A disaccharide was clearly mapped in the structure, which involved in regulating the esterolytic activity of AhV_TL-I. The presence of the N-glycan deformed the 99-loop, and the resulting steric hindrances hindered the substrates to access the active site. Furthermore, with the carbohydrate moiety, AhV_TL-I could induce mouse thoracic aortic ring contraction with the EC(50) of 147 nmol/L. Besides, the vasoconstrictor effects of AhV_TL-I were also independent of the enzymatic activity. The results of [Ca(2+)](i) measurement showed that the vasoconstrictor effects of AhV_TL-I were attributed to Ca(2+) releasing from Ca(2+) store. Further studies showed that it was related to the activation of ryanodine receptors (RyRs). These offer new insights into the snake SVTLEs functions and provide a novel pathogenesis of A. halys pallas venom.
Authors:
Fuxing Zeng; Bing Shen; Zhongliang Zhu; Ping Zhang; Yonghua Ji; Liwen Niu; Xu Li; Maikun Teng
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-10-11
Journal Detail:
Title:  Archives of toxicology     Volume:  -     ISSN:  1432-0738     ISO Abbreviation:  Arch. Toxicol.     Publication Date:  2012 Oct 
Date Detail:
Created Date:  2012-10-11     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0417615     Medline TA:  Arch Toxicol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230026, People's Republic of China.
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