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Chiral inversion of 2‐phenylpropionic acid by Cordyceps militaris
Author(s) -
Hung Y.F.,
Thomason M.J.,
RhysWilliams W.,
Lloyd A.W.,
Hanlon G.W.
Publication year - 1996
Publication title -
journal of applied bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 0021-8847
DOI - 10.1111/j.1365-2672.1996.tb04324.x
Subject(s) - cordyceps militaris , biotransformation , enantiomer , stereochemistry , chemistry , substrate (aquarium) , yield (engineering) , chromatography , cordyceps , biology , organic chemistry , food science , enzyme , ecology , materials science , metallurgy
Y.‐F. HUNG, M.J. THOMASON, W. RHYS‐WILLIAMS, A.W. LLOYD AND G.W. HANLON. 1996. Fifty‐nine microbial cultures were screened for their ability to carry out the chiral inversion of (R,S) and (R)‐2‐phenylpropionic acid under both growing and non‐growing conditions. While a number of these micro‐organisms metabolized the substrate, only Verticillium lecanii IMI 68689 and Cordyceps militaris CBS 128.25 were able to invert the (R)‐enantiomer to its (S)‐antipode with no other biotransformation occurring. The rate of inversion was faster for C. militaris but in both cases the reaction was independent of growth and reached an equilibrium after 5 d incubation. Evidence suggests that the (R) to (S) inversion is inhibited in the presence of excess (S)‐enantiomer which may account for the equilibrium enantiomeric ratios (S:R) of 90:10 and 70:30 for C. militaris and V. lecanii , respectively. Optimization studies revealed that the fastest rates of reaction for C. militaris were found at lower substrate concentrations (100 μg ml ‐1 ) whilst the greatest yield of (S)‐2‐PPA was obtained at 250 μg ml ‐1 . Optimum inversion was found to occur using Sørensen's phosphate buffer at pH 5.5. These results may have implications for the use of micro‐organisms in the production of pure enantiomers from racemic mixtures and, in addition, provide an in vitro model system for the study of a unique and interesting biotransformation.