Beta-Aspartokinase from developing endosperm of maize

Henke, R.R.; Wahnbaeck, R.

Biochemical and Biophysical Research Communications 79(1): 38-45

1977


ISSN/ISBN: 0006-291X
PMID: 200245
DOI: 10.1016/0006-291x(77)90057-2
Accession: 068523804

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Abstract
.beta.-Aspartokinase (EC 2.7.2.4.) was isolated from the developing endosperm (30 days post-pollination) of Zea mays (cv. Pioneer 3145). Enzyme activity was dependent upon ATP, Mg++ or Mn++, aspartate and protein concentration. Double reciprocal plots of velocity vs. aspartate concentrations deviated from a straight line at low aspartate concentration indicating 2 apparent Km of 0.5 and 6.6 mM. Enzyme activity was inhibited by lysine but not by methionine or threonine. The endosperm-derived .beta.-aspartokinase behaved similarly to enzyme isolated from 6 day old etiolated shoot tissue. The presence of .beta.-aspartokinase in developing endosperm provides new insight into the source of the aspartate-derived amino acids in maize endosperm.