Bioconversion of organosilicon compounds by horse liver alcohol dehydrogenase: the role of the silicon atom in enzymatic reactions

✍ Scribed by Min-Hua Zong; Toshiaku Fukui; Takuo Kawamoto; Atsuo Tanaka

• Publisher: Springer
• Year: 1991
• Tongue: English
• Weight: 336 KB
• Volume: 36
• Category: Article
• ISSN: 1432-0614
• DOI: 10.1007/bf00164696

✦ Synopsis

Bioconversion of three organosilicon compounds of different chain length between the silicon atom and the hydroxyl group (Me3Si(CH2)nOH, n = 1-3) by horse liver alcohol dehydrogenase (HLADH, EC 1.1.1.1.) was studied. Furthermore, the effect of the silicon atom on the HLADH-catalysed reaction was examined in comparison with the corresponding carbon compounds. HLADH could catalyse the dehydrogenation of trimethylsilylethanol (n = 2) and trimethylsilylpropanol (n=3). Trimethylsilylethanol was a better substrate than both its carbon analogue, 3,3-dimethylbutanol, and ethanol. The improved activity of HLADH on trimethylsilylethanol could be accounted for by a higher affinity toward HLADH and a lower activation energy of the reaction by HLADH than those of the carbon counterpart. These are derived from physical properties of the silicon atom, that is, the lower electronegativity and the bigger radius than those of the carbon atom. In contrast, HLADH showed no activity on trimethylsilylmethanol (n= 1), whereas it catalysed the dehydrogenation of the carbon analogue, 2,2-dimethylpropanol, fairly well. The reason for the inactivity of HLADH in the case of trimethylsilylmethanol based on the electric effect of the silicon atom is also discusssed.