Premium
Fluorescent pigments by covalent binding of lipid peroxidation by‐products to protein and amino acids
Author(s) -
Fukuzawa Kenji,
Kishikawa Katsuya,
Tokumura Akira,
Tsukatani Hiroaki,
Shibuya Masayuki
Publication year - 1985
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/bf02534768
Subject(s) - chemistry , oleic acid , amino acid , ricinoleic acid , linoleic acid , glycine , organic chemistry , fatty acid , chromatography , biochemistry , castor oil
The fluorescent products formed on reaction of 12‐oxo‐ cis ‐9‐octadecenoic acid (12‐keto‐oleic acid) with about 20 different amino acids, polylysine and bovine serum albumin (BSA) were studied. Besides glycine, only the basic amino acids histidine, lysine and arginine gave products with strong fluorescence. N‐Acetylation of amino acids greatly reduced the fluorescence of their reaction products. The formation of fluorescent products was inhibited strongly by SH‐amino acids such as N‐acetyl‐cysteine and glutathione. Polyacrylamide gel electrophoresis showed that BSA treated with 12‐keto‐oleic acid was more acidic than untreated or ricinoleic acid‐treated BSA, indicating that basic amino acid residues in BSA were modified by reaction with the keto fatty acid. None of the structural analogs of 12‐keto‐oleic acid tested–12‐oxo‐ trans ‐10‐octadecenoic acid, 12‐oxo‐octadecanoic acid, 12‐hydroxy‐ cis ‐9‐octadecenoic acid (ricinoleic acid), cis ‐9‐octadecenoic acid (oleic acid) and linoleic acid—reacted with glycine to give a fluorescent product. The fluorescent products formed on reaction of 12‐keto‐oleic acid methyl ester with benzyl amine and glycine methyl ester were shown to be 8‐(N‐substituted‐4,5‐dihydro‐4‐oxo‐5‐hexyl‐5‐hydroxy‐2‐pyrrolyl) octanoic acid methyl esters. The fluorescence properties of these compounds were attributed to the chromophobic system NC=CC=O which contains 6π electrons. This investigation contributes to insight of the mechanism of formation of fluorescent pigments, probably by a similar reaction of other compounds of the β,γ‐unsaturated carbonyl type.