Effect of carbohydrates and polyols on amide content and protein fragmentation in a lactoglobulin preparation

Abstract

Certain carbohydrates and polyols are used at various stages of the production of immunobiological preparations as stabilizers of biological activity, particularly in the production of lactoglobulin (against opportunistic pathogens) using membrane ultrafiltration. This study concerns the effect of these substances on changes in the amide content in proteins of this lactoglobulin. Lactoglobulin was incubated in near-physiological (0.9% NaCl, pH 5.5) 10% solutions of glucose, fructose, and sorbitol at 4 and 35 degrees C for 7, 14, and 28 days. A lactoglobulin solution in 0.9% NaCl, pH 5.5, was used as the control. All substances studied suppressed the reduction of the amide group content of asparagine and, in contrast, increased the rate of amide group removal from glutamine residues in proteins of lactoglobulin preparations.