Benign synthesis of 2-ethylhexanoic acid by cytochrome P450cam: enzymatic, crystallographic, and theoretical studies.
This study examines the ability of P450cam to catalyze the formation of 2-ethylhexanoic acid from 2-ethylhexanol relative to its activity on the natural substrate camphor. As is the case for camphor, the P450cam exhibits stereoselectivity for binding (R)- and (S)-2-ethylhexanol. Kinetic studies indicate (R)-2-ethylhexanoic acid is produced 3.5 times as fast as the (S)-enantiomer. In a racemic mixture of 2-ethylhexanol, P450cam produces 50% more (R)-2-ethylhexanoic acid than (S)-2-ethylhexanoic acid. The reason for stereoselective 2-ethylhexanoic acid production is seen in regioselectivity assays, where (R)-2-ethylhexanoic acid comprises 50% of total products while (S)-2-ethylhexanoic acid comprises only 13%. (R)- and (S)-2-ethylhexanol exhibit similar characteristics with respect to the amount of oxygen and reducing equivalents consumed, however, with (S)-2-ethylhexanol turnover producing more water than the (R)-enantiomer. Crystallographic studies of P450cam with (R)- or (S)-2-ethylhexanoic acid suggest that the (R)-enantiomer binds in a more ordered state. These results indicate that wild-type P450cam displays stereoselectivity toward 2-ethylhexanoic acid synthesis, providing a platform for rational active site design.
French
K J
KJ
Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, New York 14642, USA.
Strickler
M D
MD
Rock
D A
DA
Rock
D A
DA
Bennett
G A
GA
Wahlstrom
J L
JL
Goldstein
B M
BM
Jones
J P
JP
D002164:Camphor / Q000378:metabolism; D019475:Camphor 5-Monooxygenase / Q000302:isolation & purification / Q000378:metabolism*; D002208:Caproates / Q000378:metabolism*; D003198:Computer Simulation; D018360:Crystallography, X-Ray; D007700:Kinetics; D008958:Models, Molecular; D015394:Molecular Structure; D017434:Protein Structure, Tertiary; D016958:Pseudomonas putida / Q000201:enzymology
D002208:Caproates; C040668:2-ethylhexanoic acid; D002164:Camphor; D019475:Camphor 5-Monooxygenase