The Proteins, Third Edition, Volume IV is a four-chapter text that explores the unifying concepts of protein chemistry and the methods of analysis that can be applied to most proteins. The first chapter deals with the biological origins and subsequent evolution of proteins. This chapter also provides the various procedures for comparing amino acid sequences and for establishing the relatedness of protein structures. A discussion on gene duplication as a principal vehicle of evolutionary change is also included in this chapter. Chapter 2 focuses on chromosomal proteins, such as those proteins associated with the genetic material of eukaryotic organisms, specifically the protamines, the histones, and the ""nonhistone"" proteins. Chapter 3 is devoted to contractile proteins of muscle. This chapter describes the molecular processes whereby chemical energy is converted into the mechanical energy required for the propulsion of living creatures. The structure and function of the individual proteins of the contractile apparatus and their organization as evidenced by light and electron microscopy and by X-ray analysis are also covered. Chapter 4 deals with collagen, an important constituent of the extracellular connective tissues in animals and one of the most abundant proteins. This chapter emphasizes the biosynthesis of collagen fibrils. Organic chemists and researchers, teachers and undergraduate students will find this book invaluable.