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Inhibition of Soybean Lipoxygenase‐1 by N‐oleoyl‐Dtryptophan
Author(s) -
Johnson Cody L.,
Clapp Charles H.
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.789.16
Subject(s) - chemistry , tryptophan , non competitive inhibition , lipoxygenase , kinetics , substrate (aquarium) , phenylalanine , polyunsaturated fatty acid , stereochemistry , biochemistry , conjugated system , enzyme , biophysics , fatty acid , amino acid , biology , organic chemistry , ecology , physics , quantum mechanics , polymer
Soybean lipoxygenase‐1 (SBLO‐1) is a nonheme iron protein that catalyzes the oxygenation of polyunsaturated fatty acids using molecular oxygen, resulting in conjugated diene hydroperoxides. Although the three‐dimensional structure of SBLO‐1 is known, it is not certain how substrates bind. Following the discovery that N‐linoleoyl‐ D‐tryptophan is an excellent substrate for SBLO‐1, N‐oleoyl‐ D‐tryptophan (ODT) was synthesized as a potential competitive inhibitor. Potent inhibition was observed at micromolar concentrations of ODT. Kinetic analysis demonstrated that ODT had only small effects on V max , indicating that the inhibition is nearly competitive; however, the inhibition is strikingly non‐linear, which implies that OTD and substrate can bind simultaneously. Similar behavior was observed with N‐oleoyl‐ L‐tryptophan and N‐oleoyl‐D‐phenylalanine. Slow oxygenation of ODT was detected by HPLC, which indicates that ODT can access the active site. However, the inhibition kinetics imply that ODT binds more effectively somewhere else. Funded by NSF grant CHE‐1213262.