Author: Mr. Nageshwar Sahu
Volume: 01
First Online: 2026
Pages: 106-172
DOI: https://doi.org/10.63785/978-81-685195-6-5/03

Abstract

Proteins are essential biological macromolecules that perform structural, catalytic, transport, regulatory, and defensive functions in living organisms. This chapter discusses the composition, classification, and biological significance of proteins,
along with the structure, properties, and classification of amino acids. It explains the four levels of protein organization—primary, secondary, tertiary, and quaternary structures—and their relationship to protein function. The chapter also covers the
physiological importance of essential and non-essential amino acids and the metabolic pathways involved in amino acid catabolism, including transamination, deamination, and the urea cycle. Furthermore, it describes enzyme nomenclature, classification, catalytic mechanisms, specificity, and regulation through inhibition and allosteric control. Understanding protein structure, metabolism, and enzyme function is fundamental to biochemistry, providing insights into cellular processes, disease mechanisms, clinical diagnosis, and therapeutic development.