Gene expression and development : the third of five volumes constituting the proceedings of the 4th International Congress on Isozymes, held in Austin, Texas, June 14-19, 1982 / editors, Mario C. Rattazzi, John G. Scandalios, Gregory S. Whitt.
- International Congress on Isozymes
- Date:
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Credit: Gene expression and development : the third of five volumes constituting the proceedings of the 4th International Congress on Isozymes, held in Austin, Texas, June 14-19, 1982 / editors, Mario C. Rattazzi, John G. Scandalios, Gregory S. Whitt. Source: Wellcome Collection.
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![Glycerol Phosphate Dehydrogenase Expression / 43 due in part to spontaneous deamidation of asparginyl and glutaminyl residues. The deamidation of asparginyl and glutaminyl residues for any single peptide can produce two peptide spots (ie, T-27 and T-27* in Fig. 4a) identical in composition but differing by a single charge. On this basis, peptide T-19 on the GPDH^-1 map and peptide T-18 on the GPDH'^-S map were identified as the deamidated forms not present in the native polypeptide chain. Still, the number of peptides observed is close to the number expected if native GPDH is composed of two identical subunits. In addition, the tryptic maps for GPDH^-1 and GPDH^'-S are strikingly similar with respect to total number and relative position of each spot. The soluble peptides from each map were subsequently isolated and sub¬ jected to a compositional analysis [Niesel, 1980]. In all but one instance, the homologous peptides had identical amino acid compositions demonstrat¬ ing that the primary structure of each isozyme is highly conserved and must represent a common if not identical primary sequence [Niesel et al, 1982; Niesel, 1980]. A single tryptic peptide, T-1, was found to be different in composition between these two isozymes (Table IV). The sequence analysis of peptide T-1 is illustrated in Figure 5. This peptide was identified as the carboxyl-terminal peptide of both GPDH^-1 and GPDH^-3 on the following basis: 1) It was the only tryptic peptide recovered that did not contain a lysyl or arginyl residue, 2) S. aureus V8 protease digestion (which cleaves on the carboxyl side of glutamyl residues) of GPDH^-1 produced a fragment, SP- 1, containing the predicted five carboxyl-terminal residues (see Table IV and Figs. 5,6). The isolation of this fragment precluded the possibility that, on TABLE IV. Amino Acid Composition of the Carboxy-Terminal Peptides of GPDH''-1 and GPDH^-3 GPDH''-Р GFDH'^-l'' GPDH'^-a Amino acid T-1 Sp-1 T-1 ®Tryptic peptide T-1 of GPDH^'-l. ''Staphylococcus aureus V8 protease peptide Sp-1 of GPDH'^-l. ^'Tryptic peptide T-1 of GPDH''-З. Data from Niesel et al [1982] with permission.](https://iiif.wellcomecollection.org/image/b18019742_0064.JP2/full/800%2C/0/default.jpg)
