Steady-state kinetic mechanism of LodA, a novel cysteine tryptophylquinone-dependent oxidase.
LodA is a novel lysine-ε-oxidase which possesses a cysteine tryptophylquinone cofactor. It is the first tryptophylquinone enzyme known to function as an oxidase. A steady-state kinetic analysis shows that LodA obeys a ping-pong kinetic mechanism with values of kcat of 0.22±0.04 s(-1), Klysine of 3.2±0.5 μM and KO2 of 37.2±6.1 μM. The kcat exhibited a pH optimum at 7.5 while kcat/Klysine peaked at 7.0 and remained constant to pH 8.5. Alternative electron acceptors could not effectively substitute for O2 in the reaction. A mechanism for the reductive half reaction of LodA is proposed that is consistent with the ping-pong kinetics.
Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32827, United States.
Esha
E
Sehanobish
Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32827, United States.
Sooim
S
Shin
Department of Genetics and Microbiology, University of Murcia, Murcia 30100, Spain.
Antonio
A
Sanchez-Amat
Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32827, United States. Electronic address: victor.davidson@ucf.edu.
Victor L
VL
Davidson
D015074:2-Aminoadipic Acid / Q000031:analogs & derivatives / Q000737:chemistry; D001426:Bacterial Proteins / Q000737:chemistry*; D003067:Coenzymes / Q000737:chemistry; D004151:Dipeptides / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D045563:Indolequinones / Q000737:chemistry*; D007700:Kinetics; D008239:Lysine / Q000737:chemistry; D053544:Marinomonas / Q000201:enzymology*; D008956:Models, Chemical; D011506:Proteins / Q000737:chemistry*
D001426:Bacterial Proteins; D003067:Coenzymes; D004151:Dipeptides; D045563:Indolequinones; D011506:Proteins; C447619:cysteine tryptophylquinone; C509674:marinocine protein, Marinomonas mediterranea; D015074:2-Aminoadipic Acid; C000061:allysine; D008239:Lysine
Amine oxidase; Cofactor; Lysine oxidase; Quinoprotein; Redox enzyme