Interactions of copper with glycated proteins:Possible involvement in the etiology of diabetic neuropathy

  • John W. Eaton
  • Mingwei Qian
Part of the Developments in Molecular and Cellular Biochemistry book series (DMCB, volume 37)


Humans and animals with diabetes frequently develop peripheral vascular dysfunction and peripheral neuropathies. There is accumulating evidence that impaired peripheral nerve function may derive from diminished endoneural blood flow. The decrements in nerve blood flow may, in turn, be due to diminished endothelium-dependent vasodilation. Although a number of possible causes of this defective vasodilation have been suggested, none has been definitely proven. Regardless of the precise cause, the impaired vasodilatory activity may reflect diminished availability of endothelium-derived relaxing factor (EDRF), variously thought to be nitric oxide or thiol adducts of nitric oxide. Other investigators have reported that administration of transition metal chelators to diabetic rats corrects EDRF-mediated arterial relaxation and restores both neural blood flow and nerve conduction velocity, suggesting the involvement of transition metals. Our investigations center about the hypothesis that glycated proteins bind transition metals such as copper and iron, and that such ‘glycochelates’ accumulate within the vasculature in diabetes and catalytically inactivate EDRF. In partial support of this hypothesis: (1) Glycated albumin binds ~ 3-fold greater amounts of both copper and iron. (2) Copper bound to glycated albumin remains redox active (e.g. capable of supporting the oxidation of ascorbic acid). (3) Copper and copper-containing glycochelates cause the rapid decomposition of one putative form of EDRF, nitrosocysteine. (4) The amount of exchangeable (i.e. chelatable) copper in the plasma of diabetic rats is approximately twice that in normal rat plasma. (5) Similarly, tail tendons of diabetic animals have about twice as much bound copper as do tendons of normal rats. (6) Implants bearing adsorbed glycated albumin placed in the peritonea of normal mice for 48 h accumulate ~ 5 times as much bound copper as do implants coated with control albumin. Overall, these observations support — but do not conclusively prove — the hypothesis that transition metals such as copper, bound to glycated proteins, may blunt normal EDRF-dependent relaxation of diabetic arteries and provide a rationale for the use of transition metal chelators in the therapy of diabetic vasculopathy and neuropathy. (Mol Cell Biochem 234/235: 135–142, 2002)

Key words

endothelium-derived relaxing factor diabetic neuropathy copper nitrosothiol nitric oxide glycation glycochelates 


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  1. 1.
    Pieper GM: Review of alterations in endothelial nitric oxide production in diabetes: Protective role of arginine on endothelial dysfunction. Hypertension 31: 1047–1060, 1998PubMedCrossRefGoogle Scholar
  2. 2.
    Cosentino F, Luscher TF: Endothelial dysfunction in diabetes mellitus. J Cardiovasc Pharmacol 32(suppl 3): S54–S61, 1998PubMedGoogle Scholar
  3. 3.
    Cameron NE, Cotter MA: Neurovascular dysfunction in diabetic rats. Potential contribution of autoxidation and free radicals examined using transition metal chelating agents. J Clin Invest 96: 1159–1163, 1995PubMedCrossRefGoogle Scholar
  4. 4.
    Honing ML, Morrison PJ, Banga JD, Stroes ES, Rabelink TJ: Nitric oxide availability in diabetes mellitus. Diabetes Metab Rev 14: 241–249, 1999Google Scholar
  5. 5.
    Cosentino F, Hishikawa K, Katusic ZS, Luscher TF: High glucose increases nitric oxide synthase expression and superoxide anion generation in human aortic endothelial cells. Circulation 96: 25–28, 1997PubMedCrossRefGoogle Scholar
  6. 6.
    Wolff SP, Dean RT: Glucose autoxidation and protein modification. The potential role of ‘autoxidative glycosylation’ in diabetes. Biochem J 245: 243–250, 1987PubMedGoogle Scholar
  7. 7.
    Wolff SP, Jiang ZY, Hunt JV: Protein glycation and oxidative stress in diabetes mellitus and ageing. Free Radic Biol Med 10: 339–352, 1991PubMedCrossRefGoogle Scholar
  8. 8.
    Wolff SP: Diabetes mellitus and free radicals. Free radicals, transition metals and oxidative stress in the zetiology of diabetes mellitus and complications. Br Med Bull 49: 642–652, 1993PubMedGoogle Scholar
  9. 9.
    Bucala R, Tracey KJ, Cerami A: Advanced glycosylation products quench nitric oxide and mediate defective endothelium-dependent vasodilatation in experimental diabetes. J Clin Invest 87: 432–438, 1991PubMedCrossRefGoogle Scholar
  10. 10.
    Myers PR, Minor RL Jr, Bates JN, Harrison DG: Vasorelaxant properties of the endothelium-derived relaxing factor more closely resemble S-nitrosocysteine than nitric oxide. Nature 345: 171–173, 1990CrossRefGoogle Scholar
  11. 11.
    Stamler JS, Simon DI, Osborne JA, Mullins ME, Jaraki O, Michel T, Singel DJ, Loscalzo J: S-nitrosylation of proteins with nitric oxide: Synthesis and characterization of biologically active compounds. Proc Natl Acad Sci USA 89: 444–448, 1992PubMedCrossRefGoogle Scholar
  12. 12.
    Kowaluk EA, Fung HL: Spontaneous liberation of nitric oxide cannot account forin vitrovascular relaxation by S-nitrosothiol. J Pharmacol Exp Ther 255: 1256–1264, 1990PubMedGoogle Scholar
  13. 13.
    Ignarro LJ, Edwards JC, Gruetter DY, Barry BK, Gruetter CA: Possible involvement of S-nitrosothiols in the activation of guanylate cyclase by nitroso compounds. FEBS Lett 110: 275–278, 1980PubMedCrossRefGoogle Scholar
  14. 14.
    Ignarro LJ, Lippton H, Edwards JC, Bancos WH, Hyman AL, Kadowitz PJ, Gruetter CA: Mechanism of vascular smooth muscle relaxation by organic nitrates, nitrites, nitroprusside and nitric oxide: Evidence for the involvement of S-nitrosothiols as active intermediates. J Pharmacol Exp Ther 218: 739–749, 1981PubMedGoogle Scholar
  15. 15.
    Ignarro LJ: Biosynthesis and metabolism of endothelium-derived nitric oxide. Annu Rev Pharmacol Toxicol 30: 535–560, 1990PubMedCrossRefGoogle Scholar
  16. 16.
    Kaufmann MA, Castelli I, Pargger H, Drop LJ: Nitric oxide dose-response study in the isolated perfused rat kidney after inhibition of endothelium-derived relaxing factor synthesis: The role of serum albumin. J Pharm Exp Ther 273: 855–862, 1995Google Scholar
  17. 17.
    Liu L, Hausladen A, Zeng M, Que L, Heitman J, Stamler JS: A metabolic enzyme for S-nitrosothiol conserved from bacteria to humans. Nature 410: 490–494, 2001PubMedCrossRefGoogle Scholar
  18. 18.
    Moya MP, Gow AJ, McMahon TJ, Toone EJ, Cheifetz IM, Goldberg RN, Stamler JS: S-nitrosothiol repletion by an inhaled gas regulates pulmonary function. Proc Natl Acad Sci USA 98: 5792–5797, 2001PubMedCrossRefGoogle Scholar
  19. 19.
    Keegan A, Cotter MA, Cameron NE: Effects of chelator treatment on aorta and corpus cavernosum from diabetic rats. Free Radic Biol Med 27: 536–443, 1999PubMedCrossRefGoogle Scholar
  20. 20.
    Nitenberg A, Paycha F, Ledoux S, Sachs R, Attali JR, Valensi P: Coronary artery responses to physiological stimuli are improved by deferoxamine but not by L-arginine in non-insulin-dependent diabetic patients with angiographically normal coronary arteries and no other risk factors. Circulation 97: 736–743, 1998PubMedCrossRefGoogle Scholar
  21. 21.
    Cameron NE, Cotter MA: Effects of an extracellular metal chelator on neurovascular function in diabetic rats. Diabetologia 44: 621–628, 2001PubMedCrossRefGoogle Scholar
  22. 22.
    Qian M, Eaton JW: Glycochelates and the etiology of diabetic peripheral neuropathy. Free Radic Biol Med 28: 652–656, 2000PubMedCrossRefGoogle Scholar
  23. 23.
    Qian M, Liu M, Eaton JW: Transition metals bind to glycated proteins forming redox active ‘glycochelates’: Implications for the pathogenesis of certain diabetic complications. Biochem Biophys Res Commun 250: 385–389, 1998PubMedCrossRefGoogle Scholar
  24. 24.
    Meola JM, Vargas MA, Brown HH: Simple procedure for measuring total protein in urine. Clin Chem 23: 975–977, 1977PubMedGoogle Scholar
  25. 25.
    Saville B: A scheme for the colorimetric determination of microgram amounts of thiols. Analyst 83: 670–672, 1958CrossRefGoogle Scholar
  26. 26.
    Cook JA, Kim SY, Teague D, Krishna MC, Pacelli R, Mitchell JB, Vodovotz Y, Nims RW, Christodoulou D, Miles AM, Grisham MB, Wink DA: Convenient colorimetric and fluorometric assays for Snitrosothiols. Anal Biochem 238: 150–158, 1996PubMedCrossRefGoogle Scholar
  27. 27.
    Makino T: A sensitive direct colorimetric assay of serum copper using 5-Br-PSAA. Clin Chim Acta 185: 7–16, 1989PubMedCrossRefGoogle Scholar
  28. 28.
    Richard S, Tamas C, Sell DR, Monnier VM: Tissue-specific effects of aldose reductase inhibition on fluorescence and cross-linking of extracellular matrix in chronic galactosemia. Relationship to pentosidine cross-links. Diabetes 40: 1049–1056, 1991PubMedCrossRefGoogle Scholar
  29. 29.
    Tang L, Eaton JW: Fibrin(ogen) mediates acute inflammatory responses to biomaterials. J Exp Med 178: 2147–2156, 1993PubMedCrossRefGoogle Scholar
  30. 30.
    McAninly J, Williams DLH, Askew SC, Butler AR, Russell C: Metal ion catalysis in nitrosothiol (RSNO) decomposition. J Chem Soc Chem Commun 1758–1759, 1993Google Scholar
  31. 31.
    Singh RJ, Hogg N, Joseph J, Kalyanaraman B: Mechanism of nitric oxide release from S-nitrosothiols. J Biol Chem 271: 18596–18603, 1996PubMedCrossRefGoogle Scholar
  32. 32.
    Pieper GM, Siebeneich W: Diabetes-induced endothelial dysfunction is prevented by long-term treatment with the modified iron chelator, hydroxyethyl starch conjugated-deferoxamine. J Cardiovasc Pharmacol 30: 734–738, 1997PubMedCrossRefGoogle Scholar
  33. 33.
    Farias-Eisner R, Chaudhuri G, Aeberhard E, Fukuto JM: The chemistry and tumoricidal activity of nitric oxide/hydrogen peroxide and the implications to cell resistance/susceptibility. J Biol Chem 271: 6144–6151, 1996PubMedCrossRefGoogle Scholar
  34. 34.
    Brenner AJ, Harris ED: A quantitative test for copper using bicinchoninic acid. Anal Biochem 226: 80–84, 1995PubMedCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 2002

Authors and Affiliations

  • John W. Eaton
    • 1
  • Mingwei Qian
    • 1
  1. 1.Department of Medicine and James Graham Brown Cancer CenterUniversity of LouisvilleLouisvilleUSA

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