Human serum, cysteine and histidine inhibit the oxidation of low density lipoprotein less at acidic pH

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 inves...

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Bibliographic Details
Published in:FEBS letters 1998-09, Vol.434 (3), p.317-321
Main Authors: Patterson, Rebecca A, Leake, David S
Format: Article
Language:English
Subjects:
Acidic pH
Alanine - metabolism
Antioxidant
Antioxidants - metabolism
Atherosclerosis
Blood
Copper
Copper - metabolism
Cysteine - metabolism
Extracellular Space
Histidine - metabolism
Humans
Hydrogen-Ion Concentration
Lipoproteins, LDL - metabolism
Low density lipoprotein
Oxidation-Reduction
Oxidized low density lipoprotein
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Summary: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.
ISSN:0014-5793
1873-3468
DOI:10.1016/S0014-5793(98)01002-3