QUANTITATION OF HOMOCYSTEINE IN HUMAN PLASMA BY CAPILLARY-ELECTROPHORESIS AND LASER-INDUCED FLUORESCENCE DETECTION

Homocysteine (Hcy) represents a branching point between the transsulfu ration and transmethylation pathway of methionine. A large increase of plasma concentration of Hey is observed in patients with inherited hy perhomocysteinemia. A moderated increase (above 10 mu M) is also obser ved in various pathological conditions, such as arterial occlusion, hy pertension, hyperlipidemia and chronic renal failure. While amino acid s were largely studied using capillary electrophoresis with UV or lase r-induced fluorescence detection (LIF), thiol-amino acids were not. In this work we present a new approach for testing homocysteine in human plasma using CE-I,LF and fluorescein isothiocyanate. The low fluoresc ence yield of the fluorescein thiocarbamyl (FTC) thiol-amino acids lim its, probably, the sensitivity of the detection to 8.10(-10) M (instea d of 10(-12) M for FTC-arginine). (C) 1998 Elsevier Science B.V. All r ights reserved.