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Biomedical subjects

G L Choules

Publications and source records attributed to G L Choules.

10 recordsLinked to original sources
PubMed1972

Glutamate dehydrogenase from Mycoplasma laidlawii.

Mycoplasma laidlawii possesses a single glutamate dehydrogenase (GDH) with dual coenzyme specificity [specificity for nicotinamide adenine dinucleotide (H) and nicotinamide adenine dinucleotide phosphate (H)]. A purification procedure is reported which results in an enzyme preparation with a specific activity of 79.5 units/mg and which displays only one significant protein band after gel electrophoresis. This one band was determined, by activity staining, to have all of the GDH nucleotide specificities. The molecular weight of the enzyme is 250,000 +/- 10%, and it has a subunit size of about 48,000. The enzyme exhibits measurable activity with aspartate and pyruvate but is inactive with eight other possible substrates. Purine nucleotides do not affect the activity. The K(m) for reduced nicotinamide adenine dinucleotide was 1.8 x 10(-4)m. The optimal substrate concentrations and pH optimum for each of the respective GDH activities are also reported.

Acholeplasma laidlawii↗
PubMed1971

Kinetics of sodium dodecyl sulfate solubilization of Mycoplasma laidlawii plasma membranes.

The kinetics of sodium dodecyl sulfate solubilization of aqueous suspensions of Mycoplasma laidlawii membranes have been investigated by light scattering in a stopped-flow apparatus. There was evidence of direct interaction between the membranes and sodium dodecyl sulfate micelles above the critical micelle concentration, although of lower order kinetically than with monomeric dodecyl sulfate anions below the critical micelle concentration. The activation energy remained the same in either case, about 10 kcal/mol. Static light-scattering studies at higher resolution showed that the solubilized membranes are in the form of small aggregates.

Acholeplasma laidlawii↗