Subunit structure of sesame 13S globulin.

Abstract

On SDS-polyacrylamide gel electrophoresis, sesame seed 13S globulin was separated into three intermediary subunits termed IS1 IS2 and IS3. Following a treatment with 0.2M 2-mercaptoethanol, the globulin was separated into three acidic subunits termed AS1 AS2 and AS3, and four basic subunits termed BS1 BS2, BS3 and BS4. Two dimensional SDS-gel electrophoresis before and after treatment with 0.2 M 2-mercaptoethanol revealed that IS1 was composed of two combinations of acidic and basic subunits, these being S1 and BS2, and AS2 and BS2. IS2 was found to be composed of AS3 and BS1, and IS3 was composed of AS2 and BS3, and AS2 and BS4. These combinations were consistent with the reactivity of each subunit to a fluorescent thiol reagent. The amino acid compositions were similar among the three acidic subunits and also among the four basic subunits. However, between the acidic and basic subunits, there were great differences in the amino acid composition, especially in the amount of glutamic acid.