Polymeric glutenins

Wieser, H., Bushuk, W., MacRitchie, F. 2006. The polymeric glutenins. In Wrigley, C., Bekes, F., Bushuk, W. (Eds.), Gliadin and Glutenin The Unique Balance ofWheat Quality, St. Paul American Association of Cereal Chemistry, St. Paul, MN, pp. 213-240. 

The gliadins are considered to impart viscous properties to dough and the polymeric glutenins elastic properties. However, one group of glutenin proteins, the HMW subunits, has been shown to play a major role in determining dough elasticity. 

Ewart (1990) [10] criticized Shewry s classification, arguing that the polymeric glutenins are fundamentally different from the monomeric gliadins because of their intermolecular disulfide bonding capacity [11]. 

Fu, B. X., and H. D. Sapirstein. 1996. Procedure for isolating monomeric proteins and polymeric glutenin of wheat flour. Cereal Chemistry 73 143-152. 

The wheat storage proteins without interchain disulfide bonds are monomeric and are termed gliadins, those with interchain disulfide bonds are polymeric and are called glutenins. Gliadins plus glutenins form gluten. Originally, it was assumed that the toxicity for CD patients was restricted to... 

HMW MMW LMW Polymeric Monomeric Monomeric Polymeric HMW subunits of glutenins ai-Type gliadins a-Type and 7-type gliadins LMW subunits of glutenins HMW secalins ai-Secalins 40 K 7-secalins 75 K 7-secalins D-hordeins C-hordeins 7-Hordeins B-hordeins... 

The sulfur-rich prolamins are quantitatively the most abundant group in wheat, barley and rye, accounting for approximately 80-90% of total prolamin fractions. They include polymeric and monomeric components and consist of at two families in each species, the B- and y-hordeins of barley two types of y-secalin of rye and a, 3 and y-gliadins and LMW glutenin subunits of wheat. The sulfur-poor prolamins include C-hordeins of barley, (O-secalin of rye and co-gliadin of wheat. 

In contrast, the glutenins form large polymeric structures as a result of inter-molecular disulfide bonds. 

Figure 13.11 SDS-PAGE of polymeric protein (after reduction to subunits). Group A HMW glutenin subunits showing x- and y-type subunits. Group B-, C-, D- LMW glutenin subunits. Arrow indicates subunit D [41].

Gluten is a complex mixture of gliadins (monomeric gluten proteins) and glutenins (polymeric gluten proteins) comprise about 80% of the proteins present in wheat grain. 

Procedures for effecting sharper separation of monomeric from polymeric fractions based on solubility have been reported by Fu and Kovacs (1999) and Fu and Sapirstein (1996). The extent of the error has been investigated by Cinco-Moroyoqui (2001), who introduced an alternative procedure for quantifying glutenin subunits. This consisted of fraction collection of the polymeric protein from SE-HPLC followed by reduction... 

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