β-Aspartokinase from developing endosperm of maize

Purification and Characterization of Lysine-Sensitive Aspartate Kinase from Maize Cell Cultures

“…BMS cell cultures may not have expressed the threonine-sensitive activity which has been detected at low levels in maize seedlings (4), or perhaps the threonine-sensitive form was unstable during extraction and purification. However, our data and those previously reported (6,8,11) favor only lysine-sensitive AK isoforms in maize.…”

Synthesis of the Aspartate Family and Branched-Chain Amino Acids

“…Reproducible evidence for a threonine-sensitive activity was not obtained with preparations derived from young etiolated maize seedlings (Bryan et al, 1970;Cheshire and Miflin, 1975;Gengenbach et al, 1978), roots, developing kernels, callus, or suspension cultures (Gengenbach et al, 1978). Henke and Wahnbaeck (1977) obtained similar results with enzyme isolated from endosperm and seedlings, although the enzyme appeared to be much less sensitive to inhibition by lysine than that obtained from other varieties of maize (Table III,A). Systematic analysis of aspartate kinase during the growth of etiolated seedlings revealed neither quantitative nor qualitative changes in the sensitivity to inhibition by lysine or threonine (J.…”

“…Aspartate kinase catalyzes the initial reaction of the pathway and has been detected in extracts or partially purified preparations derived from a wide variety of plants. With the maize enzyme, two apparent K m values can be delineated from double reciprocal plots of velocity versus aspartate concentration (Bryan et al, 1970;Henke and Wahnbaeck, 1977). Each of these enzymes is characterized by regulatory properties which rein force the conclusion that aspartate kinase is the first enzyme in a multibranched biosynthetic pathway as indicated in Fig.…”

Partial Purification and Characterization of Dihydrodipicolinic Acid Reductase from Maize

“…The first enzyme, aspartate kinase, has been found in a variety ofplants, including maize (10). Aspartic semialdehyde dehydrogenase has been detected in pea-seedlings extracts ( 19).…”