Non-enzymatic glycation of IgG: an in vivo study.
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.
Lapolla
Annunziata
A
Dipartimento Scienze Mediche e Chirurgiche, Università di Padova, Via Giustiniani 2, 35100 Padua, Italy. annunziata.lapollo-@unipd.it
Tonani
R
R
Fedele
D
D
Garbeglio
M
M
Senesi
A
A
Seraglia
R
R
Favretto
D
D
Traldi
P
P
D000368:Aged; D001786:Blood Glucose / Q000378:metabolism; D001798:Blood Proteins / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism; D005260:Female; D005947:Glucose / Q000378:metabolism; D006442:Glycated Hemoglobin / Q000378:metabolism; D006023:Glycoproteins / Q000378:metabolism; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000737:chemistry / Q000378:metabolism; D007074:Immunoglobulin G / Q000737:chemistry / Q000378:metabolism*; D008239:Lysine / Q000031:analogs & derivatives* / Q000097:blood; D008297:Male; D008875:Middle Aged; D008958:Models, Molecular; D011506:Proteins / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D001786:Blood Glucose; D001798:Blood Proteins; D005947:Glucose; D006442:Glycated Hemoglobin; D006023:Glycoproteins; D007140:Immunoglobulin Fab Fragments; D007074:Immunoglobulin G; D008239:Lysine; D011506:Proteins; C018948:furosine