Thein vivoGlyco-oxidation of α- and β-Globins Investigated by Matrix-assisted Laser Desorption/Ionization Mass Spectrometry

Abstract

Matrix-assisted laser desorption/ionization (MALDI) has been employed for the determination of molecular weights of alpha- and beta-globins obtained from blood samples of healthy and diabetic subjects. Glycated species, originating from the reaction of glucose with the proteins, are easily evident. The MALDI measurements allowed one to distinguish between simple glycation and glyco-oxidation processes of haemoglobin. In fact, together with the products arising from simple glucose condensation on the two proteins, compounds at different oxidation levels were evident. Due to its high specificity, MALDI must be considered a valuable tool for diagnosis in the diabetes field.

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

“…To verify the power of MALDI/MS in the evaluation of HbA 1c (Lapolla et al, 1996b), globin was prepared according to the usual procedures, and, in a preliminary study, samples from 3 normal subjects and 3 diabetic patients were analyzed. The MALDI spectra of healthy subjects (see Figure 13a) highlighted unexpected and never previously described behavior; two main peaks were found at m/z 15127 and 15868, which corresponded to protonated and non-glycated a-and b-globin chains, respectively.…”

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.…”

Analysis of glycated proteins by mass spectrometric techniques: qualitative and quantitative aspects

“…In contrast, MALDI-TOF mass spectrometry is able to distinguish between glycated and non-glycated species of specific proteins, as well as provide quantitative estimation of the level of glycation of the different serum proteins, such as human serum albumin (HSA) and the individual monomers of hemoglobin [47][48][49][50]. Equipped with "delayed extraction" ion source, the MALDI-TOF technique is able to reveal further degradation reactions of the sugar moieties of Amadori products of glycated proteins, such as dehydration and oxidation [51,52]. Coupled with enzymatic digests of glycated proteins, MALDI-TOF/MS of the partial hydrolysates of glycated proteins has been used to identify the glycation sites of the major intrinsic peptide (MIP) of the lens [53] and most susceptible glycation domain of immunoglobulin-G (IgG) [49].…”