title: Inhibition of testicular LDH-X from laboratory animals and man by gossypol and its isomers.
abstract: The inhibitory effect of (+)-, (-)-, (+/-)-gossypol and (+/-)-gossypol acetic acid upon testicular cytosolic LDH-X was measured in vitro. Gossypol acetic acid (0-100 mumol/l) inhibited LDH-X prepared from the testes of the mouse greater than rabbit greater than human greater than rat greater than hamster. There was no relationship between inhibition and in-vivo antifertility activity. LDH activity measured in vitro in serum of men and hamsters was unaffected by gossypol. Gossypol and its isomers were non-competitive inhibitors of human and hamster LDH-X with respect to the coenzyme NADH, competitive inhibitors of human LDH-X and noncompetitive-competitive inhibitors of hamster LDH-X with respect to the substrate alpha-ketobutyrate. Co-incubation with human serum albumin or poly-L-lysine but not lysine protected human and hamster LDH-X from gossypol.
mesh_terms: D000818:Animals; D006224:Cricetinae; D003600:Cytosol / Q000187:drug effects / Q000201:enzymology; D006072:Gossypol / Q000031:analogs & derivatives* / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D007527:Isoenzymes; D007770:L-Lactate Dehydrogenase / Q000378:metabolism*; D008297:Male; D008647:Mesocricetus; D051379:Mice; D008815:Mice, Inbred Strains; D008875:Middle Aged; D011817:Rabbits; D051381:Rats; D011919:Rats, Inbred Strains; D013737:Testis / Q000187:drug effects / Q000201:enzymology*
chemical_list: D007527:Isoenzymes; D007770:L-Lactate Dehydrogenase; D006072:Gossypol; C028178:gossypol acetic acid