- Discovery and characterization of a thermostable D-lactate dehydrogenase from Lactobacillus jensenii through genome mining
-
The demand on thermostable D-lactate dehydrogenases (d-LDH) has been increased for d-lactic acid production but thermostable d-DLHs with industrially applicable activity were not much explored. To identify a thermostable d-LDH, three d-LDHs from different Lactobacillus jensenii strains were screened by genome mining and then expressed in Escherichia coli. One of the three d-LDHs (d-LDH3) exhibited higher optimal reaction temperature (50 °C) than the others. The T5010 value of this thermostable d-LDH3 was 48.3 °C, much higher than the T5010 values of the others (42.7 and 42.9 °C) and that of a commercial D-lactate dehydrogenase (41.2 °C). The Tm values were 48.6, 45.7 and 55.7 °C for the three d-LDHs, respectively. In addition, kinetic parameter (k cat/Km) of d-LDH3 for pyruvate reduction was estimated to be almost 150 times higher than that for lactate oxidation at pH 8.0 and 25 °C, implying that D-lactate production from pyruvate is highly favored. These superior thermal and kinetic features would make the d-LDH3 characterized in this study a good candidate for the microbial production of D-lactate at high temperature from glucose if it is genetically introduced to lactate producing microbial.
- Jun, Chanha,Sa, Young Seung,Gu, Sol-A,Joo, Jeong Chan,Kim, Seil,Kim, Kyung-Jin,Kim, Yong Hwan
-
p. 109 - 117
(2013/04/10)
-
- A new family of D-2-hydroxyacid dehydrogenases that comprises D-mandelate dehydrogenases and 2-ketopantoate reductases
-
The gene for the D-mandelate dehydrogenase (DManDH) of Enterococcus faecalis IAM10071 was isolated by means of an activity staining procedure and PCR and expressed in Escherichia coli cells. The recombinant enzyme exhibited high catalytic activity toward various 2-ketoacid substrates with bulky hydrophobic side chains, particularly C3-branched substrates such as benzoylformate and 2-ketoisovalerate, and strict coenzyme specificity for NADH and NAD+. It showed marked sequence similarity with known NADP-dependent 2-ketopantoate reductases (KPR). These results indicate that together with KPR, D-ManDH constitutes a new family of D-2-hydroxyacid dehydrogenases that act on C3-branched 2-ketoacid substrates with various specificities for coenzymes and substrates.
- Wada, Yusuke,Iwai, Saho,Tamura, Yusuke,Ando, Tomonori,Shinoda, Takeshi,Arai, Kazuhito,Taguchi, Hayao
-
p. 1087 - 1094
(2008/09/21)
-