Applied Microbiology and Biotechnology, Vol.41, No.2, 219-224, 1994
Enantioselective Dehydrogenation of Beta-Hydroxysilanes by Horse Liver Alcohol-Dehydrogenase with a Novel in-Situ NAD(+) Regeneration System
Dehydrogenation of 2-trimethylsilyl-1-propanol (1) was carried out with horse liver alcohol dehydrogenase (HLADH, EC 184.108.40.206). It was found that the dehydrogenation of 1 proceeded enantioselectively with only HLADH and a catalytic amount of NAD(+) due to in-situ NAD(+) regeneration based on a specific property of beta-carbonylsilanes. That is, (+)-1 was enantioselectively dehydrogenated by HLADH to 2-trimethylsilyl-1-propanal, which was spontaneously degraded by addition of water into trimethylsilanol and n-propanal. Then, NAD(+) was regenerated through HLADH-catalyzed reduction of n-propanal to n-propanol. On the other hand, dehydrogenation of the carbon analogue of 1 was negligible with a catalytic amount of NAD(+), indicating that the in-situ NAD(+) regeneration was not available without the specific property of organosilicon compounds. Other primary beta-hydroxysilanes having different substituents on the chiral center or on the silicon atom were also found to serve as substrates in enantioselective dehydrogenation by HLADH with this novel NAD(+) regeneration system. Chiral recognition of HLADH toward primary alcohols is also discussed.