A FACTOR FROM PEA COTYLEDONS THAT MODIFIES AUXIN-INDUCED ALPHA-AMYLASE IN-VITRO

An auxin-induced a-amylase (AMY I; EC 3.2.1.1) with a low affinity for potato starch was purified to homogeneity from detached cotyledons of Pisum sativum, as judged by the presence of a single band after non-denaturing PAGE and SDS-PAGE. AMY I was compared with a previously purified auxin-induced alpha-amylase (AMY II) that had a higher affinity for potato starch. No difference between AMY I and AMY II was apparent after SDS-PAGE or isoelectric focusing (IEF) and rates of degradation of soluble starch were identical. However, AMY I was less active than AMY II in the degradation of starch granules. A factor that converted AMY II to AMY I in vitro was detected in a crude extract of detached cotyledons. The factor was heat-labile.