DNA FRAGMENT ENCODING ASPARTOKINASE-III, A METHOD OF L-THREONINE PREPARING

摘要

FIELD: biotechnology, microbiology. SUBSTANCE: DNA fragment encodes aspartokinase-III showing amino acid sequence of "wild" type. This sequence has mutation that eliminates inhibition of aspartokinase-III activity by feedback inhibition mechanism. Mutation is taken from the group: Gly-323 is replaced for Asp; Gly-323 for Asp and Gly-408 for Asp; Arg-34 for Cys and Gly-323 for Asp; Leu-325 for Phe; Met-318 for Ile; Met-318 for Ile and Val-349 for Met; Ser-345 for Leu; Val-347 for Met; Trp-352 for Ile; Trp-352 for Ile and Ser-369 for Phe; Glu-164 for Lys; Met-417 for Ile and Cys-419 for Tyr. Method of L-threonine preparing involves culturing the strain-producer of genus Escherichia transformed with recombinant plasmid DNA containing above indicated DNA fragment. Strain is cultured on fermentation medium followed by isolation of L-threonine. EFFECT: improved method of amino acid preparing. 2 cl, 7 dwg , 6 tble