Soybean lipoxygenase: substrate structure and product selectivity.
1995
Scheller G. | Jager E. | Hoffmann B. | Schmitt M. | Schreier P.
To study the influence of structural properties of the substrate on the selectivity of the dioxygenation catalyzed by soybean lipoxygenase (LOX), a number of synthesized (Z,Z)-3,6-dienyl 1-adipates with various distal residues were used and the kinetic parameters, the regioselectivity, and the enantioselectivity of product formation determined. Product analysis comprised the reduction of hydroperoxides, derivatization to their methyl esters, purification by silica gel chromatography, and subsequent HPLC separation of (Z,E)-1,3-hydroxydiene methyl esters using both achiral and chiral phases. Enantioseparations were performed by HPLC on chiral phases employing both underivatized products and naphthoylate derivatives. The calculation of the hydrophobicity difference between the distal and the proximal residues of the substrate was confirmed to be a quantitative parameter to predict the positional specificity of the enzymic catalysis. Higher enantiomeric excess was observed only for 7-oxygenated products; 3-oxygenated products were found to be racemic.
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