STEREOSELECTIVITY OF MICROBIAL LIPASES - THE SUBSTITUTION AT POSITIONSN-2 OF TRIACYLGLYCEROL ANALOGS INFLUENCES THE STEREOSELECTIVITY OF DIFFERENT MICROBIAL LIPASES
P. Stadler et al., STEREOSELECTIVITY OF MICROBIAL LIPASES - THE SUBSTITUTION AT POSITIONSN-2 OF TRIACYLGLYCEROL ANALOGS INFLUENCES THE STEREOSELECTIVITY OF DIFFERENT MICROBIAL LIPASES, European journal of biochemistry, 227(1-2), 1995, pp. 335-343
In the present study, the stereoselectivity of purified lipases from C
andida rugosa, Chromobacterium viscosum, Pseudomonas species and Rhizo
pus arrhizus towards triacylglycerols in comparison to various structu
ral analogs were investigated. Different triacylglycerol analogs with
distinct polarities at position sn-2 of the glycerol backbone (1,3-dia
cyl-2-X-glycerol, where 2-X = 2-acyloxy, 2-alkyloxy, 2-deoxy-2-alkyl,
or 2-deoxy-2-phenyl) were synthesized. Substrate hydrophobicity and st
eric requirement was modified by variation of the alkyl and acyl chain
length. Hydrolysis of these substrates demonstrated that minor struct
ural variations at C2 of triacylglycerol strongly affect the stereosel
ectivity of the lipases tested. It was noteworthy that the variation o
f substrate structure did not only affect the quantity of stereoselect
ivity expressed as percentage enantiomeric excess, but also resulted i
n a reversal of stereo-preference in some cases. Replacement of the ac
ylester in position 2 of glycerol by a non-ester-linked aliphatic moie
ty shifted the preference of Chromobacterium viscosum lipase from sn-3
to sn-1. Lipases from Chromobacterium viscosum, Pseudomonas species a
nd Rhizopus arrhizus exhibited sn-3 preference with 2-deoxy-2-phenyl a
nalogs, while towards substrates with a 2-deoxy-2-alkyl moiety sn-1 st
ereobias was recorded. Candida rugosa lipase was rather insensitive to
substrate variations concerning the polarity at position 2 of the gly
cerol backbone. However, variation of the acyl chain length significan
tly influenced stereoselectivity of this lipase.