Secondary structure predictions for the NAD-specific glutamate dehydrogenase of Neurospora crassa

From the amino acid sequences of the three known fragments of the NAD-specific glutamate dehydrogenase of Neurospora crassa, the secondary structures have been predicted from the rules of Chou and Fasman (Chou, P.Y., and Fasman, G.D. (1979) Biophys. J. 26, 367-384). Comparison of these structures with those calculated for bovine glutamate dehydrogenase has shown that in the regions of homologous sequences containing identified functional regions, there is considerable homology of structure. From these predictions, it has been possible to identify a putative coenzyme-binding domain in the COOH-terminal part of the molecule similar to those of various NAD-specific dehydrogenases. Residues whose modification alters coenzyme binding are located in the putative coenzyme binding domain. The major sites of tryptic cleavage of the native enzyme, described in an accompanying paper (Haberland, M.E., Chen, C.-W., and Smith, E.L. (1980) J. Biol. Chem. 255, 7993-8000), are in regions of random coil structure.