Regiochemical and stereochemical evidence for enzyme-initiated catalysis in dual positional specific maize lipoxygenase-1.
Dual positional specific maize lipoxygenase-1 catalyzed the formation of racemic mixtures of four possible regioisomers and was strongly inhibited by the radical scavenger, 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinoxy radical. Molecular modeling studies indicated that the oxygen-binding cavity is segregated from the substrate-binding cavity. The data suggest that a bis-allylic radical reaction intermediate is generated enzymatically, released from the enzyme active site, and subsequently oxygenated outside of the enzyme active site by a nonenzymatic mechanism.
Jang
Sungkuk
S
Department of Molecular Biotechnology, Biotechnology Research Institute, College of Agriculture and Life Sciences, Chonnam National University, Kwangju 500-757, Republic of Korea.
Huon
Thavrak
T
Kim
Keumhwa
K
Um
Eunji
E
Han
Oksoo
O
D001665:Binding Sites; D002384:Catalysis; D003497:Cyclic N-Oxides / Q000494:pharmacology*; D016166:Free Radical Scavengers / Q000494:pharmacology*; D008084:Lipoxygenase / Q000378:metabolism*; D015394:Molecular Structure; D013113:Spin Labels; D013237:Stereoisomerism; D003313:Zea mays / Q000201:enzymology*
D003497:Cyclic N-Oxides; D016166:Free Radical Scavengers; D013113:Spin Labels; D008084:Lipoxygenase; C001803:tempol