Diastereoselective synthesis of (R)-(alkyl)-beta-D-galactopyranoside by using beta-galactosidase (Aspergillus oryzae) in low-water media.
A beta-galactosidase (from Aspergillus oryzae) preparation viz. EPRP (enzyme precipitated and rinsed with propanol), obtained by the removal of bulk water by precipitation with n-propanol, showed higher biological activity than the lyophilized powder. FT-IR study confirmed that EPRP had retained the alpha-helical content of the native structure better than the lyophilized form. Use of this formulation of beta-galactosidase under low water conditions (temperature 55 degrees C, reaction time of 4 h) gave enantioselectivity, E > 1000 for the stereoselective synthesis of (R)-(1-phenylethyl)-beta-D-galactopyranoside, starting from racemic 1-phenylethanol and D-galactose. For racemic 2-octanol also, EPRP worked better. Under similar conditions, (R)-(2-octyl)-beta-D-galactopyranoside was formed with an enantioselectivity, E = 38.
Majumder
Abir B
AB
Chemistry Department, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110 016, India.
Singh
Bhupender
B
Gupta
Munishwar N
MN
D001236:Aspergillus oryzae / Q000201:enzymology*; D005612:Freeze Drying; D005697:Galactosides / Q000138:chemical synthesis*; D017550:Spectroscopy, Fourier Transform Infrared; D013237:Stereoisomerism; D014867:Water / Q000737:chemistry; D001616:beta-Galactosidase / Q000737:chemistry* / Q000378:metabolism
D005697:Galactosides; C087303:octyl galactopyranoside; D014867:Water; D001616:beta-Galactosidase