Glyceraldehyde-3-phosphate dehydrogenase. Investigation on the regions responsible for self-assembly of subunits

Abstract

1. 1. In glyceraldehyde-3-phosphate dehydrogenase (GAPDH)(EC 1.2.1.12) the four S-loop form the core of the tetramer. 2. 2. Amino acid sequence of the S-loop of the regions of GAPDH from carp muscle was established through the analysis of tryptic digests of the enzyme treated alternatively with bromocyanate and o-iodosobenzoic acid. 3. 3. Enzyme had been oxidized with performic acid. After treatment with trypsin the peptide mixture was fractionated into fragments. 4. 4. CNBr cleavage of this enzyme was performed after S-carboxymethylation. The respective cyanogen bromide fragments have been isolated and characterized. 5. 5. The procedure of protein fragmentation by o-iodosobenzoic acid used to split tryptophanyl peptide bonds. 6. 6. Each peptide obtained after enzymatic or chemical fragmentation was purified to homogeneity by Bio-Gel or Sephadex chromatography, high voltage electrophoresis and descending paper chromatography and characterized by electrochromatography, N- and C-terminal sequence and amino acid composition. 7. 7. The results are compared with those obtained from studies on GAPDH from other sources.