High-Molecular Group HMW Subunits of Glutenin

As shown in Table 15.15, the HMW subunits of glutenin are the only gluten proteins in which Gly (ca. 19%), and not Pro (ca. 12%), takes second place in the order of amino acids after Glx (ca. 36%). Furthermore, the proteins are characterized by the highest content of T)t (ca. 6%) and Thr (ca. 3.5%) and the lowest content of Phe (ca. 0.3%) and He (ca. 0.8%). In the N-ter-minal amino acid sequence presented in Table 15.16, the sequence EGEAS-RQLQC is valid for all known HMW subunits and varies only in position 6 (E, K, G). Erom the total sequences known until now, it can be deduced that the HMW subunits consist of three segments (A-C in Table 15.17). The N- and C-terminal segments 

The relative molecular masses (Mr) calculated from the known total sequences are 67,000-88,000, while the molecular masses derived from SDS-PAGE are 35-40% higher (Table 15.14). 

The N-terminal sequences consist of the sequence SRLLSPRGKELHT and are typical of this type 

The LMW type is named after the first amino acid in the sequence, serine (s) or methionine (m). 

In acidic PAGE, col,2-gliadins have the lowest mobility. The molecular masses are in the range Mr = 34,000-44,000. 

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