Biochemical properties of alcohol dehydrogenase from Drosophila lebanonensis.

摘要: Purified Drosophila lebanonensis alcohol dehydrogenase (Adh) revealed one enzymically active zone in starch gel electrophoresis at pH 8.5. This was located on the cathode side of origin. Incubation D. Adh with NAD+ and acetone altered electrophoretic pattern to more anodal migrating zones. has an Mr 56,000, a subunit 28 000 is dimer two sites per enzyme molecule. agrees polypeptide chain 247 residues. Metal analysis by plasma emission spectroscopy indicated that this insect not metalloenzyme. In studies substrate specificity stereospecificity, secondary than primary alcohols. Both alkyl groups alcohols interacted hydrophobically binding region site. The catalytic centre activity for propan-2-ol 7.4 s-1 maximum velocity most approximately same indicative rate-limiting enzyme-coenzyme dissociation. For varied much lower ethanol 2.4 s-1. With [2H6]ethanol kinetic 2H isotope effect 2.8 interconversion ternary complexes rate-limiting. Pyrazole ethanol-competitive inhibitor enzyme. difference spectra enzyme-NAD+-pyrazole complex gave absorption peak 305 nm epsilon 14.5 X 10(3) M-1 cm-1. Concentrations amounts can thus be determined. A rate assay determine concentration also presented. been developed from site concentrations established titration pyrazole NAD+. contrast amino acid composition, which melanogaster alleloenzymes were closely related, enzymological showed their similar although differing markedly those zinc dehydrogenases.