title: Characterization of the guanidinobenzoatase in the epididymal fluids of the mouse.
abstract: 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 (K(m) of 6.66 microM 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.
authors.affiliation: Department of Biology, University of Alabama, Birmingham 35294, USA.
authors.forename: Z L
authors.initials: ZL
authors.lastname: Barksdale
authors.forename: S E
authors.initials: SE
authors.lastname: Caldwell
authors.forename: D J
authors.initials: DJ
authors.lastname: Aarons
authors.forename: S B
authors.initials: SB
authors.lastname: Young
authors.forename: G R
authors.initials: GR
authors.lastname: Poirier
mesh_terms: D000177:Acrosome / Q000502:physiology; D000818:Animals; D001826:Body Fluids / Q000737:chemistry; D002265:Carboxylic Ester Hydrolases / Q000302:isolation & purification* / Q000378:metabolism; D002614:Chelating Agents / Q000494:pharmacology; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D004527:Egg Proteins / Q000378:metabolism / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D010450:Endopeptidases / Q000302:isolation & purification* / Q000378:metabolism; D004822:Epididymis / Q000737:chemistry*; D005260:Female; D007700:Kinetics; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism / Q000494:pharmacology; D051379:Mice; D008813:Mice, Inbred ICR; D011956:Receptors, Cell Surface; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology; D013084:Sperm-Ovum Interactions; D014361:Trypsin Inhibitors / Q000494:pharmacology; D015044:Zona Pellucida / Q000378:metabolism; D000072216:Zona Pellucida Glycoproteins
chemical_list: D002614:Chelating Agents; D004527:Egg Proteins; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; D015842:Serine Proteinase Inhibitors; D014361:Trypsin Inhibitors; D000072216:Zona Pellucida Glycoproteins; C000606521:Zp3 protein, mouse; D004533:Egtazic Acid; D002265:Carboxylic Ester Hydrolases; C037288:guanidinobenzoate esterase; D010450:Endopeptidases