Non-enzymatic glycosylation of dietary protein in vitro

Abstract

Non-enzymatic glycosylation of proteins, based on discovered by Mayam reaction of carbohydrate aldehyde group with a free amino group of a protein molecule, is well known to experts in biochemistry of food industry. Generated brown solid in some cases give the product marketable qualities - crackling bread - in others conversely, worsen the product. The biological effects of far-advanced products of non-enzymatic protein glycosylation reaction have not been studied enough, although it was reported previously that they are not split by digestive enzymes and couldn't be absorbed by animals. The objective of this work was to compare the depth of glycosylation of different food proteins of animal and vegetable origin. The objects of the study were proteins of animal (casein, lactoglobulin, albumin) and vegetable (soy isolate, proteins of rice flour, buckwheat, oatmeal) origin, glucose and fructose were selected as glycosylation agents, exposure 15 days at 37° C. Lactoglobulin was glycosylated to a lesser extent among the proteins of animal origin while protein of oatmeal was glycosylated in the least degree among vegetable proteins. Conversely, such proteins as casein and soya isolate protein bound rather large amounts of carbohydrates. Fructose binding with protein was generally higher than the binding of glucose. The only exception was a protein of oatmeal. When of glucose and fructose simultaneously presented in the incubation medium, glucose binding usually increased while binding of fructose, in contrast, reduced. According to the total amount of carbohydrate (meg), which is able to attach a protein (mg) the studied food proteins located in the following order: albumin (38) > soy protein isolate (23) > casein (15) > whey protein = rice flour protein (6) > protein from buckwheat f lour (3) > globulin (2) > protein of oatmeal (0,3). The results obtained are to be used to select the optimal combination of proteins and carbohydrates, in which the glycosylation during storage will be minimal