title: Preliminary physico-chemical characterization of the soluble Mn2+-dependent adenylate cyclase in the rat testis.
abstract: This paper reports some physico-chemical properties of the Mn+-dependent adenylate cyclase (AC) of the rat testis. The AC activity in the crude cytosol (106 000 x g) migrates as a single peak in a linear sucrose gradient (5--20%) with a sedimentation coefficient (S20,w) of 4,1. The enzyme exhibits an Einstein-Stokes radius (rs) of 30.6 A as assessed by gel filtration (Kav = 0.50) on a calibrated Sephadex G-200 column. The molecular shape is close to spherical (f/f0 = 1.25). Isoelectric focussing of the AC peak (Kav = 0.50) from the Sephadex G-200 column revealed a pI of 5.7. Ion exchange chromatography of the crude cytosol on a Whatman DE-52 column gave a single peak eluting between 0.13--0.17 M NaCl. Electrophoresis on polyacrylamide gels resulted in a migrating AC peak with an apparent Rf of 0.40 relative to bromophenol blue. The Mn2+-dependent AC is not retained on a Con-A Sepharose 4B column indicating that the enzyme molecule does not contain sugars possessing alpha-D-manno- or alpha-D-glucopyranosyl terminal groups. (NH4)2SO4 precipitates the AC activity (4 degrees C) between 30--60% saturation. The yield approximates 85% of total AC activity with the specific activity reaching a plateau (110 pmoles cAMP/mg protein/min.) at 50% saturated (NH4)2SO4. The soluble Mn+-dependent AC of the rat testis thus appears to be relatively symmetrical with a size of approximately 52 000 D and a negative charge at physiological pH. Apparently it does not contain sugar moieties and it exhibits little molecular heterogeneity.
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D002499:Centrifugation, Density Gradient; D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D007525:Isoelectric Focusing; D007526:Isoelectric Point; D008297:Male; D008345:Manganese / Q000378:metabolism*; D008970:Molecular Weight; D051381:Rats; D013737:Testis / Q000201:enzymology*
chemical_list: D008345:Manganese; D000262:Adenylyl Cyclases