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Article: Proteins
- Article from:
- Chemistry: Foundations and Applications
- Author:
CopyrightCOPYRIGHT 2004 The Gale Group, Inc. This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights should be directed to the Gale Group. (Hide copyright information)
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Proteins
Excluding the water present in the human body, about one half of the remaining mass is composed of a class of molecules called proteins. It should therefore be of no surprise that proteins carry out many important biological processes.
Amino Acids
Proteins are essentially natural polymers composed of long chains of subunits. These smaller units are called amino acids. One "end" of an amino acid has acidic character because it has a carboxyl (COOH)
functional group
. The other end has basic character because it has an amino (NH
2
) functional group. When two amino acids react, they form what is called a peptide bond. The resulting molecule, called a dipeptide, still has one end ...