C-TERMINAL AND INTERNAL SEQUENCES OF A LOW-MOLECULAR-WEIGHT (LMW-S) TYPE OF GLUTENIN SUBUNIT

Amino acid sequences have been determined for a 25-residue C-terminal peptide and for two 9-residue peptides, all derived from cyanogen brom ide fragmentation of a low molecular weight glutenin subunit (LMW-GS) with the N-terminal sequence: serine-histidine-isoleucine-proline-glyc ine-(LMW-s type). Previously, only N-terminal amino acid sequences hav e been available for LMW-s types, which appear to be the predominant L MW-GS type in hexaploid and tetraploid wheats. N-terminal sequences an d complete sequences based on DNA sequences have been available, howev er, for subunits of the LMW-m type. These have the N-terminal sequence : methionine-glutamic acid-threonine-serine-cysteine-. All three pepti des prepared from the LMW-s type subunit showed strong sequence simila rities to LMW-m type subunits from hexaploid and tetraploid bread whea ts. The 25-residue C-terminal fragment was 80% identical to DNA-derive d sequences of specific LMW-m types. Two of the peptides contained cys teine and showed homology around these cysteines with LMW-m type seque nces. The results support the basic similarity between LMW-s and LMW-m glutenin subunits.