The activities of porcine lactate dehydrogenase (LHD) isoenzymes were analyzed using nicotinamide-adenine dinucleotide (NAD) or its analogs as a cofactor, with varying concentrations of L-lactate from 13 to 530 mM. The greatest differences between H4-type and M4-type isoenzymes in reaction rates were observed when their activities were compared in a reaction mixture containing 530 mM lactate and NAD, and also in a system of 13 mM lactate with thionicotinamide-hypoxanthine dinucleotide as a cofactor. The ratio of the LDH activity exerted in the former reaction mixture to that exerted in the latter was termed the N/T value. The N/T values of porcine H4 and M4 isoenzymes were 0.49 and 9.33, respectively. The N/T values of other three isoenzymes (H3M1, H2M2 and H1M3) were calculated by assuming that the single subunits H1 and M1 contribute one-fourth of the values of 0.49 and 9.33, respectively, and a given isoenzyme which is a combination of four subunits of H and M comprises the sum of their values. The calculated values agreed fairly well with the experimental results. The N/T value method was found to be applicable to human LDH isoenzymes, and sera from various patients were analyzed in comparison with hormonal sera. The method is particularly suitable for the numerical expression of LDH isoenzyme profiles.

Animals↗

PubMed1976

Application of nicotin amide-adenine dinucleotide analogs for clinical enzymology: alcohol dehydrogenase activity in liver injury.

The activities of alcohol dehydrogease(ADH) in serum and in the subcellular fractions of rat liver were determined with n-amyl alcohol or ethanol as substrate and thionicotinamide-adenine dinucleotide as coenzyme. It was found that the enzyme's activity ratio on the amyl alcohol and ethanol(A/E value) of serum and on the particulate fractions of the liver were different, but the A/E value of the soluble fraction was similar to that of serum. The A/E value of the particulate fractions were higher than that of the soluble fraction. From the results of experimental liver damage in the rat, it seems that estimation of the A/E value of ADH activity in serum is a useful parameter for the diagnosis of active liver injury. Since the A/E values of patients' sera differed from those of the normal subjects, the estimation of the A/E value of serum may give diagnostic information on liver injury, especially in chronic liver injury.

Alanine Transaminase↗

PubMed1975

A clinical method for the determination of serum gamma-glutamyl transpeptidase.

A simple, highly sensitive and reproducible method for the assay of gamma-glutamyl transpeptidase (EC 2.3.2-) activity is introduced, using gamma-glutamyl-p-nitroanilide as a substrate and glycylglycine as an acceptor in 50 g/l of polyoxyethylene nonylphenol. Serum transpeptidase activity was assayed in 1080 healthy adults, the normal mean value being 14.8 mU/ml. The diagnostic evaluation of the enzyme in various hepatobiliary diseases is also discussed.

Adult↗

PubMed1973