Homocysteine binds to human plasma fibronectin and inhibits its interaction with fibrin

Arterioscler Thromb Vasc Biol. 2002 Aug 1;22(8):1354-9. doi: 10.1161/01.atv.0000023899.93940.7c.

Abstract

Objective: More than 70% of circulating homocysteine is disulfide-bonded to protein, but little is known about the specific proteins that bind homocysteine and their function as a consequence of homocysteine binding.

Methods and results: When human plasma was incubated with [(35)S]L-homocysteine, most of the homocysteine bound to albumin. However, additional homocysteine-binding proteins were detected, and 1 of them comigrated with fibronectin. Treatment with 2-mercaptoethanol removed the bound homocysteine, demonstrating the involvement of disulfide bonding. In contrast, [35S]L-cysteine did not bind to fibronectin. Purified fibronectin bound approximately 5 homocysteine molecules per fibronectin dimer. SDS-PAGE of a limited trypsin digestion of homocysteinylated fibronectin showed that several tryptic fragments contained [35S]homocysteine. Sequence analysis demonstrated that the fragments containing bound homocysteine had localized mainly to the C-terminal region, within and adjacent to the fibrin-binding domain. Homocysteinylation of fibronectin significantly inhibited its capacity to bind fibrin by 62% (P<0.005). In contrast, neither the binding of fibronectin to gelatin nor its capacity to serve as an attachment factor for aortic smooth muscle cells was affected.

Conclusions: These results suggest that homocysteine may alter normal thrombosis and delay or interfere with wound healing by impairing the interaction of fibronectin with fibrin.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Arteriosclerosis / blood
  • Binding, Competitive
  • Fibrin / metabolism*
  • Fibronectins / blood*
  • Fibronectins / metabolism
  • Gelatin / metabolism
  • Homocysteine / blood*
  • Humans
  • In Vitro Techniques
  • Muscle, Smooth, Vascular / metabolism
  • Thrombosis / blood

Substances

  • Fibronectins
  • Homocysteine
  • Gelatin
  • Fibrin