title: A further study of human seminal plasma lactate dehydrogenase-C4 (LDH-C4): kinetic properties of LDH-C4.
abstract: Lactate dehydrogenase-C4 (LDH-C4) from human seminal plasma was purified by 40-60% (NH4)2SO4 precipitation, Oxamate-Sepharose 4B affinity column chromatography and AMP affinity column chromatography. Enzyme kinetic studies of human seminal plasma LDH-C4 were performed with purified LDH -C4. The human LDH-C4 exhibits a much higher affinity for pyruvate and alpha-ketovalerate than lactate. Apparent Km values for pyruvate, alpha-ketovalerate and lactate were 7.7 X 10(-5) M, 1.3 X 10(-3) M and 6.7 X 10(-3) M, respectively. The human seminal plasma LDH-C4 was severely inhibited by increasing concentration of substrate, especially lactate. These kinetic properties were compared with those of previous reports of human spermatozoa.
authors.affiliation: Department of Urology, Saitama Medical Center, Saitama Medical School.
authors.forename: Y
authors.initials: Y
authors.lastname: Uchijima
authors.forename: K
authors.initials: K
authors.lastname: Yoshida
authors.forename: H
authors.initials: H
authors.lastname: Saito
mesh_terms: D045782:Hemiterpenes; D006801:Humans; D007651:Keto Acids / Q000378:metabolism; D007700:Kinetics; D007770:L-Lactate Dehydrogenase / Q000302:isolation & purification / Q000378:metabolism*; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D008297:Male; D011773:Pyruvates / Q000378:metabolism; D019289:Pyruvic Acid; D012661:Semen / Q000201:enzymology*; D013094:Spermatozoa / Q000201:enzymology
chemical_list: D045782:Hemiterpenes; D007651:Keto Acids; D007773:Lactates; D011773:Pyruvates; D019344:Lactic Acid; C001505:alpha-ketoisovalerate; D019289:Pyruvic Acid; D007770:L-Lactate Dehydrogenase