Cationic substrates of soybean lipoxygenase-1.
Soybean lipoxygenase-1 (SBLO-1) catalyzes the oxygenation of 1,4-dienes to produce conjugated diene hydroperoxides. The best substrates are anions of fatty acids; for example, linoleate is converted to 13(S)-hydroperoxy-9(Z),11(E)-octadecadienoate. The manner in which SBLO-1 binds substrates is uncertain. In the present work, it was found that SBLO-1 will oxygenate linoleyltrimethylammonium ion (LTMA) to give primarily13(S)-hydroperoxy-9(Z),11(E)-octadecadienyltrimethylammonium ion. The rate of this process is about the same at pH 7 and pH 9 and is about 30% of the rate observed with linoleate at pH 9. At pH 7, SBLO-1 oxygenates linoleyldimethylamine (LDMA) to give primarily 13(S)-hydroperoxy-9(Z),11(E)-octadecadienyldimethylamine. The oxygenation of LDMA occurs at about the same rate as LTMA at pH 7, but more slowly at pH 9. The results demonstrate that SBLO-1 will readily oxygenate substrates in which the carboxylate of linoleate is replaced with a cationic group, and the products of these reactions have the same stereo- and regiochemistry as the products obtained from fatty acid substrates.
Department of Chemistry, Bucknell University, Lewisburg, PA 17837, United States.
Lucas E
LE
Chohany
Kathleen A
KA
Bishop
Hannah
H
Camic
Stephen J
SJ
Sup
Peter M
PM
Findeis
Charles H
CH
Clapp
D002412:Cations / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D019787:Linoleic Acid / Q000737:chemistry; D008084:Lipoxygenase / Q000737:chemistry* / Q000378:metabolism; D013025:Glycine max / Q000201:enzymology*; D013237:Stereoisomerism; D013379:Substrate Specificity
D002412:Cations; D019787:Linoleic Acid; C101084:lipoxygenase L-1; D008084:Lipoxygenase