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Human serum, cysteine and histidine inhibit the oxidation of low density lipoprotein less at acidic pH
Author(s) -
Patterson Rebecca A,
Leake David S
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)01002-3
Subject(s) - chemistry , histidine , low density lipoprotein , lipoprotein , extracellular , antioxidant , cysteine , biochemistry , amino acid , conjugated system , alanine , copper , cholesterol , organic chemistry , enzyme , polymer
Low concentrations of serum or interstitial fluid have been shown to inhibit the oxidation of low density lipoprotein (LDL) catalysed by copper or iron, and may therefore protect against the development of atherosclerosis. As atherosclerotic lesions may have an acidic extracellular pH, we have investigated the effect of pH on the inhibition of LDL oxidation by serum and certain components of serum. Human serum (0.5%, v/v), lipoprotein‐deficient human serum at an equivalent concentration and the amino acids l ‐cysteine (25 μM) and l ‐histidine (25 μM), but not l ‐alanine (25 μM), inhibited effectively the oxidation of LDL by copper at pH 7.4, as measured by the formation of conjugated dienes. The antioxidant protection was reduced considerably at pH 6.5, and was decreased further at pH 6.0. These observations may help to explain why LDL becomes oxidised locally in atherosclerotic lesions in the presence of the strong antioxidant protection offered by extracellular fluid.