title: Subunit structure of higher plant glyceraldehyde-3-phosphate dehydrogenases (EC 1.2.1.12 and EC 1.2.1.13).
abstract: In a previous publication (Cerff, R. (1979) Eur. J. Biochem., 94, 243--247) we demonstrated that chloroplast NADP-linked glyceraldehyde-3-P dehydrogenase (EC 1.2.1.13) from higher plants consists of two separate isoenzymes with apparent subunit compositions A2B2 (isoenzyme 1) and A4 (isoenzyme 2), where Subunits A and B are distinguished by slightly different molecular weights (A smaller than or approximately to B). In the present study we compare isoenzymes 1 and 2 from Sinapis alba and Hordeum vulgare on the basis of antigenic cross-reactivity, tryptic peptides, and amino acid composition. Isoenzymes 1 and 2 show immunochemical identity. They also have very similar tryptic peptide maps and amino acid compositions. This strongly suggests that Subunits A and B of the NADP-linked enzyme are very similar in primary sequence. As opposed to this, cytoplasmic NAD-specific glyceraldehyde-3-P dehydrogenase (EC 1.2.1.12) does not cross-react with antisera raised against the NADP-linked enzyme. Furthermore, tryptic peptide maps of the NAD-specific enzyme show little or no similarity with those of the NADP-linked enzyme. This indicates that the subunits of the NADP-linked enzyme and the subunit of the NAD-specific enzyme are different proteins coded by separate genes. The differences in the amino acid compositions between the two species corresponds to a SdeltaQ value of 21, suggesting some sequence resemblance and a common phylogenetic origin.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000302:isolation & purification; D001467:Hordeum / Q000201:enzymology; D005779:Immunodiffusion; D007527:Isoenzymes / Q000302:isolation & purification; D046911:Macromolecular Substances; D008970:Molecular Weight; D010446:Peptide Fragments / Q000032:analysis; D010944:Plants / Q000201:enzymology*; D013045:Species Specificity; D014357:Trypsin
chemical_list: D000596:Amino Acids; D007527:Isoenzymes; D046911:Macromolecular Substances; D010446:Peptide Fragments; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D014357:Trypsin