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Chapter-04 Chemistry of Amino Acids and Proteins

BOOK TITLE: Essentials of Biochemistry for Medical Students

Author
1. B Shivananda Nayak
ISBN
9788184487718
DOI
10.5005/jp/books/11024_4
Edition
1/e
Publishing Year
2010
Pages
21
Author Affiliations
1. University of the West Indies, Trinidad and Tobago, West Indies; Subbaiah Institute of Medical Sciences, Shivamogga, Karnataka, India
Chapter keywords

Abstract

Proteins are the group of organic compounds of carbon, hydrogen, oxygen and nitrogen. All the biologically active proteins comprise of nearly 22 different amino acids, which are called as building blocks of proteins. Amino acids contain two functional groups like amino (NH2) and carboxyl (COOH) group. The carbon atom attached to –NH2 group and –COOH group is called as a-carbon and “R” is the side chain of amino acid and can be hydrogen or an aliphatic group, aromatic or heterocyclic group. Amino acids are classified mainly into three groups depending on their reaction in solution as neutral, acidic and basic amino acids. Nutritionally amino acids are classified as essential and nonessential amino acids. Amino acids are of ketogenic (acetoacetic acid) and glucogenic (glucose from carbon skeleton). Amino acids joined by peptide bonds to form peptides (proteins). Proteins play a central role in cell functions and cell structure. Proteins are made up of one or more polypeptide chains. Four levels of structural organization can be recognized such as primary structure, secondary structure, tertiary structure and quaternary structure. Disruption of the secondary, tertiary and wherever applicable quaternary without affecting the primary organization of protein molecule is denaturation. Human plasma has albumin and globulins. Globulins are classified into different types. Plasma proteins can be separated by electrophoresis.

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