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Yoshio Kawahara Yasuhiko Yoshihara Shigeho Ikeda Hiroe Yoshii Yoshio Hirose 《Applied microbiology and biotechnology》1990,34(1):87-90
Summary The growth rate, sugar consumption rate, and production rate of an l-lysine producing Brevibacterium lactofermentum mutant were stimulated by addition of exogenous glycine betaine. Glycine betaine stimulated the growth rate especially in media of inhibitory osmotic stress, and the stimulation was independent of any specific solute. Therefore growth stimulation by glycine betaine was considered to be an osmoprotective effect. A strong enhancement of the sugar consumption rate and the l-lysine production rate was observed even with resting cells under osmotic stress as well as in a fermentation with growing cells. These data indicated that the osmoprotective effects of glycine betaine on l-lysine production can be independent of protein synthesis.
Offprint requests to: Yoshio Kawahara 相似文献
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Takata Y Huang Y Komoto J Yamada T Konishi K Ogawa H Gomi T Fujioka M Takusagawa F 《Biochemistry》2003,42(28):8394-8402
Methyltransfer reactions are some of the most important reactions in biological systems. Glycine N-methyltransferase (GNMT) catalyzes the S-adenosyl-l-methionine- (SAM-) dependent methylation of glycine to form sarcosine. Unlike most SAM-dependent methyltransferases, GNMT has a relatively high value and is weakly inhibited by the product S-adenosyl-l-homocysteine (SAH). The major role of GNMT is believed to be the regulation of the cellular SAM/SAH ratio, which is thought to play a key role in SAM-dependent methyltransfer reactions. Crystal structures of GNMT complexed with SAM and acetate (a potent competitive inhibitor of Gly) and the R175K mutated enzyme complexed with SAM were determined at 2.8 and 3.0 A resolutions, respectively. With these crystal structures and the previously determined structures of substrate-free enzyme, a catalytic mechanism has been proposed. Structural changes occur in the transitions from the substrate-free to the binary complex and from the binary to the ternary complex. In the ternary complex stage, an alpha-helix in the N-terminus undergoes a major conformational change. As a result, the bound SAM is firmly connected to protein and a "Gly pocket" is created near the bound SAM. The second substrate Gly binds to Arg175 and is brought into the Gly pocket. Five hydrogen bonds connect the Gly in the proximity of the bound SAM and orient the lone pair orbital on the amino nitrogen (N) of Gly toward the donor methyl group (C(E)) of SAM. Thermal motion of the enzyme leads to a collision of the N and C(E) so that a S(N)2 methyltransfer reaction occurs. The proposed mechanism is supported by mutagenesis studies. 相似文献
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The distributed data acquisition and control system consisting of two process-oriented stations supervised by a master operator-oriented
station was developed for fermentation experiment purposes. Ability of the system for study, analysis and control, as well
as adequacy of the proposed methods and strategies for process investigation were proved. Some practical experiences with
computer driven experiments on physiological state modulation ofC. utilis andB. megaterium in the laboratory fermentor are reported. 相似文献
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