Muscle d-glyceraldehyde-3-phosphate dehydrogenase from Anas sp.—2. New data on enzyme characterization

Abstract 1. 1. Adenine nucleotides were shown to inhibit GPDH activity: 3′–5t' cyclic-AMP was the most effective inhibitor. 2. 2. Incubation of Anas sp. muscle GPDH with 10 mM ATP at 0°C caused loss of 90% of the original activity. 3. 3. Incubation of Anas sp. muscle GPDH with NADH at 37°C caused inactivation of the enzyme with partial loss of —SH titrable groups. 4. 4. GPDH from Anas sp. muscle at 10 μM concentration was inactivated when incubated with glyceraldehyde-3-phosphate (G3P) at 37°C. 5. 5. The dehydrogenase activity was lost at high concentrations of urea (7M). 6. 6. Anas sp. muscle GPDH appeared to be very similar to reptilian Caiman sp. muscle enzyme under the assay conditions used.