Aspartokinase of a lysine producing mutant ofMicrococcus glutamicus |
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Authors: | Meena Lakshman B C Shenoy M R Raghavendra Rao |
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Institution: | (1) Discipline of Biochemistry and Applied Nutrition, Central Food Technological Research Institute, 570 013 Mysore |
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Abstract: | Aspartokinase fromMicrococcus glutamicus AEC RN-13-6/1 a homoserine requiring, S-(2-aminoethyl)-L-cysteine resistant, lysine producing strain] was purified 71 fold.
The partially purified enzyme was inhibited by L-lysine. L-threonine, L-methionine, L-isoleucine, L-valine and L-phenylalanine
activated the enzyme and reversed the inhibition by L-lysine. Aspartokinase activity was not derepressed by growth-limiting
concentrations of L-threonine and/or L-methionine. It was not repressed by an excess of L-lysine (20 mM) and/or L-isoleucine
(15.3 mM). The degree of activation or inhibition by amino acids was dependant on the composition of the growth medium. This
observation is in contrast with the enzyme from the original (non-lysine-producing) strain which was inhibited by lysine or
threonine and in a concerted manner by threonine plus lysine. |
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Keywords: | Aspartokinase Micrococcus glutamicus |
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