TY - JOUR
T1 - Oxidation of linoleyl alcohol by potato tuber lipoxygenase
T2 - Possible mechanism and the role of carboxylic group in substrate binding
AU - Butovich, I. A.
AU - Lukyanova, S. M.
AU - Reddy, C. C.
N1 - Funding Information:
1This work was supported by PHS Grants HL31245, DK49122, and AI38250 to C. Channa Reddy.
PY - 1998/8/19
Y1 - 1998/8/19
N2 - We have studied the aerobic oxidation of linoleyl alcohol (LAL) by potato tuber lipoxygenase in the presence of 0.02% (w/v) non-ionic detergent Lubrol PX (and its analog C12E10) and 0.1 mM sodium dodecyl sulfate to investigate the role of carboxylic group in substrate binding. While the enzyme displayed a comparable affinity toward LA and LAL, the rate of LAL oxidation was approximately one fourth of that of linoleic acid. The pH-profile of the reaction suggests that the rate of LAL oxidation is controlled by two ionizable groups with pK(a) values of 5.3 and 7.5, with optimal pH being 6.4 ± 0.1. Since LAL is not ionizable at this pH, we conclude that the rate of the reaction is controlled by two ionogenic groups of the enzyme. The primary dioxygenation product(s) of LAL had a maximal absorbance at 233 ± 1 nm. The products have been isolated, catalytically hydrogenated with H2 over Pd on carbon, and analyzed by GC-MS. Two major equimolar products were found to be 9- and 13-hydroxystearyl alcohols, indicating that 9- and 13-hydroperoxylinoleyl alcohols are the primary dioxygenation products. Based on these results we propose that the carboxyl group of polyunsaturated fatty acid may not be involved in substrate binding of potato tuber lipoxygenase.
AB - We have studied the aerobic oxidation of linoleyl alcohol (LAL) by potato tuber lipoxygenase in the presence of 0.02% (w/v) non-ionic detergent Lubrol PX (and its analog C12E10) and 0.1 mM sodium dodecyl sulfate to investigate the role of carboxylic group in substrate binding. While the enzyme displayed a comparable affinity toward LA and LAL, the rate of LAL oxidation was approximately one fourth of that of linoleic acid. The pH-profile of the reaction suggests that the rate of LAL oxidation is controlled by two ionizable groups with pK(a) values of 5.3 and 7.5, with optimal pH being 6.4 ± 0.1. Since LAL is not ionizable at this pH, we conclude that the rate of the reaction is controlled by two ionogenic groups of the enzyme. The primary dioxygenation product(s) of LAL had a maximal absorbance at 233 ± 1 nm. The products have been isolated, catalytically hydrogenated with H2 over Pd on carbon, and analyzed by GC-MS. Two major equimolar products were found to be 9- and 13-hydroxystearyl alcohols, indicating that 9- and 13-hydroperoxylinoleyl alcohols are the primary dioxygenation products. Based on these results we propose that the carboxyl group of polyunsaturated fatty acid may not be involved in substrate binding of potato tuber lipoxygenase.
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U2 - 10.1006/bbrc.1998.9148
DO - 10.1006/bbrc.1998.9148
M3 - Article
C2 - 9712698
AN - SCOPUS:0032547287
SN - 0006-291X
VL - 249
SP - 344
EP - 349
JO - Biochemical and Biophysical Research Communications
JF - Biochemical and Biophysical Research Communications
IS - 2
ER -