Biorecognition of Chemically Modified Bovine Serum Albumin with Lactose Prepared under Different Conditions

Abstract

Glycoconjugates consist of glycans attached to proteins or lipids. Glycans are involved in important biological functions such as trafficking of glycoconjugates, mediation, and modulation of cell adhesion and signaling. This study was conducted to obtain neoglycoconjugates containing a large number of carbohydrates, added through the condensation of reducing sugars with protein amino groups, whose structures were recognized by lectins. Neoglycoconjugates (BSA-Lac) of bovine serum albumin (BSA) with d-lactose were obtained using two sets of glycation conditions, each previously selected by its ability to glycate proteins extensively. The conditions included dry heat at 60 degrees C (for 7, 14, 21, and 28 days) and wet heat in 43% relative humidity (RH) at 50 degrees C (for 5, 10, 15, and 20 h). Products were characterized by gel electrophoresis, tryptophan fluorescence emission spectra, mass spectrometry, free amino group analysis, and their biological recognition established by a galactose-specific lectin and Escherichia coli K88 adhesins. BSA-Lac when compared to BSA revealed an increase in monomer mass due to addition of either 13 (dry heat) or 14 (wet heat) lactoses and formation of polymers (in wet conditions). All BSA-Lac products showed reduced intensity of intrinsic fluorescence, decreased amino groups' availability, and were recognized by Ricinus communis I lectin (RCAI) and by E. coli K88 adhesins. Overall, glycation using both conditions was time-dependent, but greater biorecognition was observed with wet-heat products, due to a higher global glycation and/or to the carbohydrate accessibility. The strategy used in this work represents a simple procedure to obtain glycoconjugates that could be used for recognition studies in biological systems.