Starch synthetase: Comparison of UDPG and ADPG as glucosyl donors in immature barley endosperm.

The activity of starch synthetase in developing barley endosperm was measured in amyloplasts and in the soluble endosperm fraction by incorporation of radioactively labelled glucose into starch. Both uridine diphosphate glucose (UDPG) and adenosine diphophate glucose (ADPG) were used as glucosyl donors. Enzyme activity was initially located in the soluble fraction, but increasing activity could be detected in the amyloplast fraction during endosperm maturation.