• Journal of Microbiology
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• 제44권1호
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• pp.50-53
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• 2006

Cys-29 and Cys-251 of Streptomyces albus valine dehydrogenase(ValDH) were highly conserved in the corresponding region of $NAD(P)^+$-dependent amino acid dehydroganase sequences. To ascertain the functional role of these cysteine residues in S. albus ValDH, site-directed mutagenesis was performed to change each of the two residues to serine. Kinetic analyses of the enzymes mutated at Cys-29 and Cys-251 revealed that these residues are involved in catalysis. We also constructed mutant ValDH by substituting valine for leucine at 305 by site-directed mutagenesis. This residue was chosen, because it has been proposed to be important for substrate discrimination by phenylalanine dehydrogenase (PheDH) and leucine dehydrogenase (LeuDH). Kinetic analysis of the V305L mutant enzyme revealed that it is involved in the substrate binding site. However it displayed less activity than the wild type enzyme toward all aliphatic and aromatic amino acids tested.

• 한국미생물·생명공학회지
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• 제28권3호
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• pp.152-155
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• 2000

곰팡이 Gibberella fujikuroi ATCC12616을 mutagen N-methyl-N-nitro-N-nitrosoguanidine과 hydroxylamine으로 처리하여 지베렐린 생산수률이 가장 높은 변이주 G. fujikuroi G-26을 선별하였다 변이주 G.fujikuroi G-36는 모균주 G.fujikuroi ATCC 12616 과 비교하여 볼 때 지베렐린 생산수율이 약 32% 향상된 것으로 관찰 되었다 이 균주를 액체배지에서 발효시키면 주 탄소원으로 sucrose를 사용할 때 높은 생산성을 나타내었으며 초기배지 pH와 온도는 각각 pH 4.0$ 28^{\circ}C$조건이 가장 좋았다 배양온도를 $30^{\circ}C$에서 3일 배양후 $20^{\circ}C$로 낮추어 7일간 배양하면 130mg/l의 가장 높은 지베렐린이 생성됨을 알았다.