Non-Enzymatic Glycation of IgG: An In Vivo Study

Abstract

The IgG glycation level of 30 healthy subjects and 60 type 2 diabetic patients with different degrees of metabolic control was evaluated by matrix-assisted laser desorption ionization mass spectrometry, a technique allowing the determination of mass increase of the IgG molecule. When applied to the digested mixture obtained by the action of papain on the plasma protein fraction, the same method established the mass increase of Fab and Fc fragments of IgG; for the former, a higher mass increase was found, possibly explained by its high reactivity to glucose. Experimental results were confirmed by molecular modeling calculations. Results suggest that the immunodeficiency observed in diabetic patients may be due to the inhibition of molecular recognition between antibody and antigen as a result of a change in functionality of the modified Fab fragment of IgG.

Key words

Non-Enzymatic Glycation - IgG - Diabetes - Mass Spectrometry - Molecular Modeling

References

• 1 Danze P, Tarjoman A, Rousseaux J, Fossati P, Dautreveaux M. Evidence for an increased glycation of IgG in diabetic patients.  Clin Chim Acta. 1987;  166 143-153
• 2 Lapolla A, Fedele D, Traldi P. The role of mass spectrometry in the study of non-enzymatic protein glycation in diabetes.  Mass Spectrometry Review. 2000;  19 1-26
• 3 Karas M, Bahr U, Giessmann U. Matrix assisted laser desorption Ionization.  Mass Spectrometry Review. 1991;  10 335-357
• 4 Lapolla A, Fedele D, Garbeglio M, Martano L, Tonani R, Seraglia R, Favretto D, Fedrigo M A, Traldi P. Matrix-assisted laser desorption/ionization mass spectrometry, enzymatic digestion and molecular modeling in the study of non-enzymatic glycation of IgG. J Am Soc.  Mass Spectrom. 2000;  11 153-159
• 5 Helsinki Declaration. W.M.A. WHO Drug Information. 1992 6(4): 186-192
• 6 Schifreen R S, Hickingbothan J M, Bowers G M. Accuracy, precision and stability in measurement of HbA1c by high performance cation exchange chromatografhy.  Clin Chem. 1980;  2 446-470
• 7 Schleicher E, Wieland O H. Specific quantification by HPLC of protein (lysine) bound glucose in human serum albumin and other glycosylated proteins. J.  Clin Chem Clin Biochem.. 1981;  19 81-87
• 8 Lee B, Richards F M. The interpretation of protein structure: estimation of static accessibility.  J Mol Biol. 1971;  55 379-400
• 9 Shrake A, Rupley J A. Enviroment and exposure to solvent of protein atoms. Lysozyme and insulin.  J Mol Biol. 1973;  79 351-371
• 10 Cohen M P. Immunoglobulins. In: Cohen MP (ed). Diabetes and protein glycation. IC Press Philadelphia; 1996: 109-111.
• 11 Hammer H P, Kiefel V, Cambe H, Federlin K. Impaired agglutination of IgM resulting from non-enzymatic glycation in diabetes mellitus.  Diab Res Clin Pract. 1990;  9 37-42
• 12 Menini T, Gugliucci A, Sthal A JC. Polyclonal immunoglobulin M: location of glycation sites.  Clin Chim Acta. 1992;  312 23-35
• 13 Dolhofer R, Siess E A, Wieland O. Non-enzymatic glycation of immunoglobulins leads to an impairment of immunoreactivity.  Hoppe Seylers 2 Phisiol Chem. 1985;  366 361-366
• 14 Hennessey P S, Back C T, Andrassy R J. Non-enzymatic glycosylation of immunoglobulin G impairs complement fixation.  J Parent Ent Nutr. 1991;  15 60-64