Cereal Chem 72:100-104  |  VIEW ARTICLE

Characterization of Low Molecular Weight Glutenin Subunits in Durum Wheat by Reversed- Phase High-Performance Liquid Chromatography and N-Terminal Sequencing.

S. Masci, E. J.- L. Lew, D. Lafiandra, E. Porceddu, and D. D. Kasarda. Copyright 1995 by the American Association of Cereal Chemists, Inc. 

Low molecular weight glutenin subunits (LMW-GS) from a residue preparation were fractionated by reversed-phase high- performance liquid chromatography (RP-HPLC) of reduced subunits from two biotypes of the Italian durum wheat cultivar Lira that differ at the Gli-B1/Glu-B3 loci, such that Lira 42 has the LMW-1 pattern (associated with poor quality) and Lira 45 has the LMW-2 pattern (associated with good quality) of LMW-GS. N- terminal amino acid sequencing was performed on the major protein fractions (peaks) that differed chromatographically between the two types. The fractions included four types of LMW-GS on the basis of their N-terminal sequences, which differed in their proportions among the various fractions. These N-terminal sequences corresponded to the Ser-His-Ile- (LMW-s) type, the Met- Glu-Thr- (LMW-m) type, the alpha-(gliadin) type, and the gamma- (gliadin) type. The LMW-s type was strongly predominant in the Lira 45 preparation and predominant in the Lira 42 preparation. The LMW- m type was next most important in the Lira 45 preparations, but in the Lira 42 preparations, the percentage of alpha-type sequence was higher than the LMW-m type. Both alpha-type and gamma-type sequences were stronger in Lira 42 than they were in Lira 45. Results indicated that differences in quality between the Lira biotypes may derive from: 1) the relative predominance in Lira 45 glutenins of the LMW-s type and the LMW-m type subunits, probably acting as glutenin polymer chain extenders; 2) the high proportion of the alpha- type and gamma-type glutenin subunits in the Lira 42 glutenins, probably included in the glutenin polymers because they have an odd number of cysteines and act as glutenin polymer chain terminators; 3) the absolute amount of LMW glutenins, which is greater for LMW-2; or 4) some combination of these factors.