DETECTION AND INVESTIGATION OF THE MOLECULAR NATURE OF LOW-MOLECULAR-MASS COPPER IONS IN ISOLATED RHEUMATOID KNEE-JOINT SYNOVIAL-FLUID

Low-molecular-mass copper(II) species have been detected and quantified in ultrafiltrates (n = 7) of rheumatoid synovial fluid (SF) by a highly-sensitive HPLC-based assay system with the ability to determine Cu(IT) concentrations of < 10(-7) mol . dm(-3). High field H-1 NMR spectroscopy demonstrated that addition of Cu(II)((aq.)) to isolated samples of RA SF ultrafiltrates resulted in complexation by histidine > alanine > formate > threonine > lactate > tyrosine > phenylalanine, their effectiveness in this context being in the given order, CD spectra of Cu(II))-treated samples of intact SF exhibited absorption bands typical of copper(II)-albumin complexes, in addition to a band attributable to a low-molecular-mass histidinate complex (lambda(min) 610 nm). Since both albumin and histidine are potent radical scavengers, these results indicate that any . OH radical generated from bound copper ions mill be 'site-specifically' scavenged. Hence, low-molecular-mass copper complexes with the ability to promote the generation of . OH radical which can then escape from the metal ion co-ordination sphere (and in turn, cause damage to critical biomolecules) appear to be absent from inflammatory SF.