Carbonyl-Amine Reactions in Protein Chemistry

Abstract

Reaction of a carbonyl group with an amino group is the key reaction in many enzymic and other biological processes, such as vision. This chapter discusses and attempts to organize and correlate the different types of carbonyl–amine reactions found in proteins with their organic chemistry. The chapter focuses on the carbonyl–-amine reaction in biological processes, naturally occurring deteriorative reactions, and their commercial applications. The most characteristic chemical property of amines is their ability to act as nucleophiles because they possess a lone pair of electrons on the nitrogen atom, while, the reactivity of the carbonyl bond is primarily because of the difference in electronegativity between carbon and oxygen, which leads to a significant contribution of the dipolar resonance form, oxygen being negative and carbon being positive. The rate of the carbonyl–amine reaction usually shows acharacteristic pH dependence that results in a bell-shaped curve. Formaldehyde reacts not only with primary amino groups in proteins, but also with sulfhydryl groups. Carbonyl–amine reactions play important roles in catalytic reactions in enzymes, cross-linking in structural proteins like collagen and elastin and the visual process.