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

Abstract

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.

• Authors: M A Mansoor, P M Ueland, A M Svardal
• Journal: The American journal of clinical nutrition (Am J Clin Nutr) Vol. 59 Issue 3 Pg. 631-5 (Mar 1994) ISSN: 0002-9165 [Print] United States
• PMID: 8116540 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Blood Proteins
• Hemoglobins
• Homocysteine
• Cysteine
• Glycine

Topics

• Aged
• Blood Proteins (metabolism)
• Cysteine (blood)
• Female
• Glycine (blood)
• Hemoglobins (analysis)
• Homocysteine (blood)
• Humans
• Male
• Oxidation-Reduction
• Protein Binding
• Vitamin B 12 Deficiency (blood)