Hypothesis

Abstract

Until recently glucose was considered by most biologists as a stable, innocuous, nonreactive molecule that serves a central metabolic role in most biologic systems. It, therefore, comes as a surprise for many to learn that glucose or other reducing sugars can react with proteins and nucleic acids without the aid of enzymes to form a series of stable covalent adducts. Although of recent interest to biologists, food chemists have been concerned with this type of chemistry ever since Maillard‘ in 1912 first incubated amino acids with glucose and observed tlie formation of yellow brown pigments. In fact, the reaction of glucose (naturally present in foods tuffs) with amino groups of proteins accounts for the golden brown color commonly observed during ~ o o k i n g . ~ . ~ The reaction of glucose with proteins in foodstuff does not require heating to occur, and can proceed slowly during the storage or aging of foods to impart unwanted changes in food quality and appearance. Presented herein is evidence for the occurrence of glucose adducts in vivo and their possible biologic significance. In addition, the hypothesis that the reaction of glucose or other reducing sugars with proteins and nucleic acids could offer an explanation for the aging of extracellular proteins as well as cells will be developed. This hypothesis offers a new framework for designing future experiments to study the complexities of aging and, liopehlly, ways to intervene. I t is important to stress that other mechanisms of aging could be occurring simultaneously. Free radical damage to proteins and deoxyribonucleic acid (DNA) is a self-evident example. However, for the sake of space, these mechanisms will not be discussed.

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