Multiple forms of starch branching enzyme of maize: Evidence for independent genetic control |
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Authors: | Charles D Boyer Jack Preiss |
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Institution: | Department of Biochemistry and Biophysics University of California Davis, California 95616 USA |
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Abstract: | Purification of starch branching enzymes from kernels of two nonlinked mutants of maize, and , showed the basis of the two mutations to be associated with branching enzymes I and IIb, respectively. Branching enzyme I from kernels purified as nonmutant branching enzyme I, but had an altered pattern of activity when amylose was used as a substrate. In addition to the typical fall in absorbance at high wavelengths (550–700 nm) of the amylose-iodine complex, branching of amylose by branching enzyme I caused an increase in absorbance at low wavelengths (400–550 nm). Branching enzyme IIb was undetected in extracts of kernels, while branching enzymes I and IIa appeared unaltered. Low umprimed starch synthase activity was also observed in DEAE-cellulose fractions of maize, but this activity was regenerated by the addition of any branching enzyme. |
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