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Characterization of the guanidinobenzoatase in the epididymal fluids of the mouse
Author(s) -
Barksdale Zachary L.,
Caldwell Scott E.,
Aarons David J.,
Young Shondria B.,
Poirier Gary R.
Publication year - 1997
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/(sici)1098-2795(199706)47:2<204::aid-mrd12>3.0.co;2-#
Subject(s) - biology , enzyme , biochemistry , trypsin , serine proteinase inhibitors , egta , gamete , molecular mass , sperm , endogeny , acrosin , epididymis , pmsf , microbiology and biotechnology , chemistry , serine protease , calcium , acrosome , botany , protease , organic chemistry
Guanidinobenzoatase (GB), a proteolytic enzyme found in the epididymal fluids of mice, was purified to apparent homogeneity by molecular sieving and affinity chromatography. It has a molecular mass of 71 kDa and its enzymatic activity is heat labile and sensitive to EGTA. Its kinetic parameters (Km of 6.66 μM and a Vmax of 4.38 nmol/min/mg) were determined using 4‐methylumbelliferyl‐p‐guanidinobenzoate (MUGB) as the substrate. GB activity is concentrated in the cauda epididymal region of the genital tract. Heat‐solubilized whole zonae, biologically active ZP3, and several serine proteinase inhibitors, including a proteinase inhibitor endogenous to the male genital tract, effectively block the ability of GB to hydrolyze MUGB. Pretreating cumulus‐free, zonae intact oocytes with purified GB reduces, in a concentration‐dependent manner, the number of sperm able to bind to the zonae. The function of the soluble enzyme is not known. Its ability to bind both trypsin inhibitors and ZP3 suggests a possible role in gamete recognition. Mol. Reprod. Dev. 47:204–209, 1997. © 1997 Wiley‐Liss, Inc.