1fiz
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(New page: 200px<br /><applet load="1fiz" size="450" color="white" frame="true" align="right" spinBox="true" caption="1fiz, resolution 2.9Å" /> '''THREE DIMENSIONAL STR...)
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Revision as of 12:50, 20 November 2007
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THREE DIMENSIONAL STRUCTURE OF BETA-ACROSIN FROM BOAR SPERMATOZOA
Overview
BACKGROUND: Proacrosin is a serine protease found specifically within the, acrosomal vesicle of all mammalian spermatozoa. During fertilization, proacrosin autoactivates to form beta-acrosin, in which there is a "light", chain cross-linked to a "heavy" chain by two disulphide bonds., beta-acrosin is thought to be multifunctional with roles in acrosomal, exocytosis, as a receptor for zona pellucida proteins, and as a protease, to facilitate penetration of spermatozoa into the egg. RESULTS: The, crystal structures of both ram and boar beta-acrosins have been solved in, complex with p-aminobenzamidine to 2.1 A and 2.9 A resolution, respectively. Both enzymes comprise a heavy chain with structural homology, to trypsin, and a light chain covalently associated in a similar manner to, blood coagulation enzymes. In crystals of boar beta-acrosin, the carboxyl, terminus of the heavy chain is inserted into the active site of the, neighboring molecule. In both enzyme structures, there are distinctive, positively charged surface "patches" close to the active site, which, associate with carbohydrate from adjacent molecules and also bind sulfate, ions. CONCLUSIONS: From the three-dimensional structure of beta-acrosin, two separate effector sites are evident. First, proteolytic activity, believed to be important at various stages during fertilization, arises, from the trypsin-like active site. Activity of this site may be, autoregulated through intermolecular associations. Second, positively, charged regions on the surface adjacent to the active site may act as, receptors for binding zona pellucida glycoproteins. The spatial proximity, of these two effector sites suggests there may be synergy between them.
About this Structure
1FIZ is a Protein complex structure of sequences from Sus scrofa with SO4 and PBZ as ligands. Full crystallographic information is available from OCA.
Reference
Effector sites in the three-dimensional structure of mammalian sperm beta-acrosin., Tranter R, Read JA, Jones R, Brady RL, Structure. 2000 Nov 15;8(11):1179-88. PMID:11080640
Page seeded by OCA on Tue Nov 20 14:57:32 2007
