In this post you can download pdf of Lippincott's Biochemistry sixth edition from here free
Proteins are the most abundant and diverse molecules in living systems. Almost all life processes depend on these large molecules. for example, Polypeptide enzymes and hormones direct and regulate the body's metabolism, while Contractile proteins in the muscles allow movement. In bones, collagen protein is a Steel cable-like calcium phosphate crystal deposition structure reinforced concrete. There are proteins such as hemoglobin and plasma in the blood Albumin is the essential shuttle molecule for life, while immunoglobulins fight infections. bacteria and viruses In short, proteins display an incredible diversity of functions, yet all share the common structural feature of being linear polymers of amino acids. This chapter describes the properties of amino acids. Chapter 2 explores how these simple building blocks are joined to form proteins that have unique three-dimensional structures, making them capable of performing specific biologic functions. Although more than 300 different amino acids have been described in nature, only 20 are commonly found as constituents of mammalian proteins. [Note: These are the only amino acids that are coded for by DNA, the genetic material in the cell.] Each amino acid has a carboxyl group, a primary amino group (except for proline, which has a secondary amino group), and a distinctive side chain (“R group”) bonded to the α-carbon atom . At physiological pH (about 7.4), the carboxyl group is Dissociates and forms amino acids with negatively charged carboxylic acid ions (–COO–) It is protonated (–NH3 +). In proteins, almost all of these carboxyl and amino groups It is linked by peptide bonds and is generally not available for chemistry. Reaction except for the formation of hydrogen bonds. So this is the nature of The side chain that ultimately determines the role that amino acids play in proteins. He, Therefore, it helps to classify amino acids based on the properties on their side. Chains, i.e. non-polar (they have a uniform distribution of electrons) or Polarity (uneven distribution of electrons such as acids and bases)
A. Amino acids with non-polar side chains Each of these amino acids has a non-polar side chain that neither acquires nor loses protons. Either participate in hydrogen or ionic bonding. Their side chains Amino acids can be thought of as "lipids" or similar lipids. Hydrophobic interaction