Lactate dehydrogenase was purified 21-fold from liver of Varanus bengalensis using colchicine-sepharose column chromatography. The crude enzyme showed two isoenzymes (LDH-5 and LDH-4) by agarose gel electrophoresis (AGE). The purified enzyme showed a single band after SDS-PAGE corresponding to molecular mass of 35 kDa. The molecular mass of native enzyme was about 140 kDa. The optimum pH for the forward reaction was 7.5 while that for the reverse reaction was pH 9.5. The K-m values for pyruvate, NADH, lactate and NAD(+) were 0.17 +/- 0.037, 0.02 +/- 0.004, 12.4 +/- 3.05 and 0.38 +/- 0.032 mM, respectively. Pre-heating of enzyme showed that its t(50) was 40-50 degrees C. Oxalate and n-hexanediol were inhibitors for both forward and reverse reactions. Among divalent ions, Cu++ was shown to be more effective inhibitor for the forward reaction.
Chromatography ; Electrophoresis, Agar Gel ; Electrophoresis, Polyacrylamide Gel ; Hydrogen-Ion Concentration ; Ions ; Isoenzymes ; L-Lactate Dehydrogenase* ; Lactic Acid* ; Liver* ; NAD ; Pyruvic Acid

The angiotensin converting enzyme (ACE) is a strong candidate gene for myocardial infarction (MI). Insertion-deletion dimorphism in intron 16 of this gene has been inconclusively found to be associated with it. Several new polymorphisms in the ACE gene have been identified and among these, a dimorphism in exon 17, ACE G2350A, has a significant effect on plasma ACE concentrations. To assess the value of genotyping the ACE G2350A dimorphism in a genetically homogeneous population, we carried out a case-control study of dimorphism G2350A for a putative association with MI among Pakistani nationals. We investigated a sample population of 370 Pakistanis, comprising 163 controls, and 207 patients with clinical diagnosis of acute MI (AMI). ACE G2350A alleles were visualized by assays based on polymerase chain reaction and restriction endonuclease analysis. Frequencies of G alleles were 0.68 among controls and 0.72 among AMI patients. The ACE G2350A dimorphism showed no significant association with MI (c2=0.90, 2 df, P=0.64), plasma levels of homocysteine (P=0.52) or with serum levels of folate (P=0.299). The results indicate that ACE G2350A polymorphism is not associated with risk of myocardial infarction in the Pakistani population investigated here.
Adult ; Aged ; Exons/*genetics ; Female ; Genetic Predisposition to Disease ; Genetics, Population ; Genotype ; Humans ; Male ; Middle Aged ; *Mutation ; Myocardial Infarction/blood/*genetics ; Peptidyl-Dipeptidase A/blood/*genetics ; *Polymorphism, Genetic ; Predictive Value of Tests