title: Substrate specificity of the lactate dehydrogenase isoenzyme C4 from human spermatozoa and a possible selective assay.
abstract: The activity of lactate dehydrogenase (EC 1.1.1.27) in normal human sperm lysates and in human heart and liver homogenates was determined by using a variety of 2-oxoacids as substrates. Sperm preparations were active with pyruvate, 2-oxobutanoate, 2-oxopentanoate and 2-oxohexanoate, while heart and liver extracts utilized only pyruvate and 2-oxobutanoate. Selective staining after gel electrophoresis indicated that the fraction corresponding to lactate dehydrogenase C4, the sperm-specific isoenzyme, was responsible for the utilization of substrates with a linear chain of 3 to 6 carbon atoms. The use of 5 mM 2-oxohexanoate allowed the selective determination of isoenzyme C4 in preparations containing different lactate dehydrogenase molecular forms.
mesh_terms: D002208:Caproates; D004592:Electrophoresis, Starch Gel; D006801:Humans; D007527:Isoenzymes; D007770:L-Lactate Dehydrogenase / Q000032:analysis / Q000378:metabolism*; D008099:Liver / Q000201:enzymology; D008297:Male; D009206:Myocardium / Q000201:enzymology; D011773:Pyruvates; D013094:Spermatozoa / Q000201:enzymology*; D013379:Substrate Specificity
chemical_list: D002208:Caproates; D007527:Isoenzymes; D011773:Pyruvates; D007770:L-Lactate Dehydrogenase