American Journal of Clinical Nutrition, Vol 59, 631-635, Copyright © 1994 by The American Society for Clinical Nutrition, Inc

ORIGINAL RESEARCH COMMUNICATIONS

Redox status and protein binding of plasma homocysteine and other aminothiols in patients with hyperhomocysteinemia due to cobalamin deficiency

MA Mansoor, PM Ueland and AM Svardal
Department of Pharmacology and Toxicology, University of Bergen, Haukeland Hospital, Norway.

We determined reduced, oxidized, and protein-bound homocysteine, cysteine, and cysteinylglycine in plasma from 13 patients with hyperhomocysteinemia (total homocysteine in the range 30.6-159.8 mumol/L) due to cobalamin deficiency. Reduced homocysteine (means +/- SD: 1.87 +/- 2.06 mumol/L) was markedly above normal (0.24 +/- 0.12 mumol/L) in most patients, and the reduced fraction increased as an exponential function of the total homocysteine concentration. The ratio of reduced homocysteine to total homocysteine was positively correlated with the reduced-total ratio for cysteine and cysteinylglycine, suggesting redox equilibrium between different aminothiol species. The free oxidized and the protein-bound forms of homocysteine account for most of the homocysteine in plasma of these patients. The amount of protein-bound homocysteine was negatively correlated with the concentrations of both protein-bound cysteine and cysteinylglycine, indicating displacement of these aminothiols by homocysteine.

This article has been cited by other articles:

				H. Refsum, C. Johnston, A. B. Guttormsen, and E. Nexo Holotranscobalamin and Total Transcobalamin in Human Plasma: Determination, Determinants, and Reference Values in Healthy Adults Clin. Chem., January 1, 2006; 52(1): 129 - 137. [Abstract] [Full Text] [PDF]

				R. Carmel, S. Melnyk, and S. J. James Cobalamin deficiency with and without neurologic abnormalities: differences in homocysteine and methionine metabolism Blood, April 15, 2003; 101(8): 3302 - 3308. [Abstract] [Full Text] [PDF]

				N. Weiss, C. Keller, U. Hoffmann, and J. Loscalzo Endothelial dysfunction and atherothrombosis in mild hyperhomocysteinemia Vascular Medicine, August 1, 2002; 7(3): 227 - 239. [Abstract] [PDF]

				L. El-Khairy, P. M Ueland, O. Nygard, H. Refsum, and S. E Vollset Lifestyle and cardiovascular disease risk factors as determinants of total cysteine in plasma: the Hordaland Homocysteine Study Am. J. Clinical Nutrition, December 1, 1999; 70(6): 1016 - 1024. [Abstract] [Full Text] [PDF]

				M. A. Mansoor, C. Bergmark, A. M. Svardal, P. E. Lonning, and P. M. Ueland Redox Status and Protein Binding of Plasma Homocysteine and Other Aminothiols in Patients With Early-Onset Peripheral Vascular Disease : Homocysteine and Peripheral Vascular Disease Arterioscler. Thromb. Vasc. Biol., February 1, 1995; 15(2): 232 - 240. [Abstract] [Full Text]