The binding of nicotinamide-adenine dimucleotide to glyceraldehyde 3-phosphate dehydrogenase from Bacillus stearothermophilus

The binding of NAD+ to glyceraldehyde 3-phosphate dehydrogenase (EC 1.2.1.12) from Bacillus stearothermophilus has been studied by measurement of protein fluorescence quenching. Slight negative co-operativity was observed in the binding of the third and fourth coenzyme molecules to the tetrameric enzyme. The first two coenzyme molecules were tightly bound. In this respect the enzyme resembles that from sturgeon muscle rather than that from yeast.