Evaluation of IgG glycation levels by matrix‐assisted laser desorption/ionization mass spectrometry

Abstract

Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry has been employed for the evaluation of the glycation level of IgG from healthy subjects and also from well- and badly-controlled diabetic patients. The measurements have been performed on untreated plasma protein fractions. The data obtained have shown that a clear mass increase, originating from non-enzymatic glycation processes, is observed in the case of diabetic patients: for well-controlled ones it is in the range 512-1565 Da, while it becomes 827-4270 Da for badly-controlled diabetic patients. This approach indicates that MALDI mass spectrometry is a highly specific tool that can be employed in the metabolic control of diabetic patients and in studies relating the IgG glycation level to possible immunological impairment.

Heterogeneity of Monoclonal Antibodies

“…In vivo glycation of human IgG in healthy subjects and increased level in diabetic patients has been widely studied. [188][189][190][191][192][193] Glycation of monoclonal and polyclonal immunoglobulins of different species can also occur in vitro 188,189,[194][195][196][197][198][199][200][201][202][203] Andya et al 56 reported that storage of the spray-dried powder of a recombinant monoclonal antibody with a molar ratio of 300:1 lactose to antibody at 308C for 9 months caused a 100% glycation of this antibody as assayed by binding to a boronate affinity column. Harris 61 reported that glycation of lysine residues of the light chain and the Fab part of the heavy chain with a molecular weight increase of 162 Da is often observed by mass spectrometry analysis.…”

The role of mass spectrometry in the study of non-enzymatic protein glycation in diabetes

“…m/z 148800.Because valid results have been obtained in evaluating the number of glucose molecules that condense onto HSA, the same method was applied to evaluate the number of glucose molecules that condense onto IgG, so as to study its in vivo glycation (Lapolla et al, 1997a). Fourteen badly controlled non-insulin±dependent diabetic patients, 8 wellcontrolled non-insulin±dependent diabetic patients, and 8 controls were studied.…”

Biomarker Characterization by MALDI–TOF/MS

“…The selection of an adequate sample preparation method relies primarily on the chemical characteristics of the targeted analytes. In some cases, biological samples can be directly analyzed without any pretreatment [198][199][200][201][202][203][204][205][206][207][208][209][210][211][212][213]. However, in most cases, simple sample preparation processes are involved, such as liquid-liquid extraction (LLE), solid-phase extraction (SPE), concentration, filtration, desalting, immunoaffinity capturing, and digestion.…”

“…Characteristic molecular profiles obtained by single-step MALDI-TOF/MS and MS/MS analyses were used for diagnosis of fucosidosis, aspartyl glucosaminuria, GM1 gangliosidosis, Sandhoff disease, α-mannosidosis, sialidosis, and type II and III mucolipidosis [202,203]. MALDI-TOF was also used to evaluate the degree of blood glycation of globins, which is involved in regulating diabetes [204][205][206][207][208][209][210][211][212]. Diluted whole blood samples were directly mixed with the organic matrix for MALDI-TOF/MS analysis [205].…”

“…MALDI-TOF was also used to evaluate the degree of blood glycation of globins, which is involved in regulating diabetes [204][205][206][207][208][209][210][211][212]. Diluted whole blood samples were directly mixed with the organic matrix for MALDI-TOF/MS analysis [205]. This approach unambiguously identified glycated α-and β-globins, the levels of which showed good linearity with those of HbA1c, a marker for evaluating long-term blood sugar levels [205,207,209,212].…”