Four chromatographically distinct forms of wheat germ agglutinin were isolated from commercial wheat germ and shown to be similar in amino acid composition, molecular weight, and isoelectric point. Three of these forms were found to undergo subunit exchange with each other or with chemically modified electrophoretic variants to give hybrid agglutinins by exposure to denaturants, pH extremes, or high salt concentrations. One form was not observed to give hybrids, probably due to intersubunit disulfide bonding. Chemical modification studies employed in obtaining electrophoretic variants indicated that acetylation or succinylation of amino groups did not markedly change the lectin dimeric subunit structure or erythrocyte agglutinating ability, but the modified protein was unable to bind to ovomucoid-Sepharose columns. Acetylation of tyrosine residues, in conjunction with amino group acylation, produced a large change in protein conformation, probably involving subunit dissociation. Carbodiimide-mediated carboxyl group modification also produced a conformational change indicative of subunit dissociation, but some binding affinity to ovomucoid-Sepharose columns was retained.
|Original language||English (US)|
|Number of pages||7|
|State||Published - 1975|
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