TheIn VitroGlycation of Lysozyme and the Influence of Buffer Concentration Investigated by Mass Spectrometry

Abstract

The non-enzymatic reactions between glucose or fructose with lysozyme, performed under pseudo-physiological conditions, have been studied by means of matrix-assisted laser desorption/ionization mass spectrometry. Phosphate buffer at concentrations of 0.05, 0.2 and 0.5 M has been employed. The formation of glycated proteins as well as of cross-linking products has been always observed. In the case of glucose, high phosphate buffer concentrations affect the glycation kinetics and promote the formation of cross-linking products. With fructose, such influence is moderate, the reaction kinetics being mainly influenced by the higher reactivity of the sugar.

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

“…Lastly, in vitro glycation of lysozyme and the in¯u-ence of buffer concentration were investigated (Lapolla et al, 1996a). Formation of glycated proteins was observed, but, interestingly, in this case peaks that corresponded to crosslinking products were also detected.…”

Protein Glycation in Diabetes as Determined by Mass Spectrometry

“…For this reason, a series of preliminary investigations were carried out on in vitro glycated different proteins [11–14]. Typical results obtained by this approach are reported in Figure 1.…”

Investigating variables and mechanisms that influence protein integrity in low water content amorphous carbohydrate matrices

“…This mass change can be assigned to protein modification resulting from the condensation of one unit of glucose or fructose with the amino group of a lysine residue on the surface of the protein. This nonenzymatic process termed protein glycation 24,25 is possible because of the hydrolysis of sucrose to yield fructose and glucose. 26 In addition to these well defined peaks, there were other less well-defined peaks/ areas within the spectrum indicative of additional chemical modifications or rearrangements that had occurred, but it was not possible to assign these from this data.…”