Chemistry of Biological Molecules

Cells are comprised of several types of polymeric macromolecules formed by joining several monomers. Some of the essential macromolecules are considered here. 

Lipids are composed of fatty acids that contain both highly hydrophobic and hydrophilic regions. Simple lipids, also referred to as glycerides, are made of three fatty acids bonded to C3 alcohol glycerol. Complex lipids are simple lipids with nitrogen, phosphorus, sulfur, or other small hydrophilic compounds. One example is phospholipids, which have a major structural role in cellular membranes. 

Nucleotides are monomers that link together to form polymers called nucleic acids deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Each nucleotide comprises a C5 sugar, a phosphate group, and a nitrogen base. Nucleotides are major constituents of the hereditary material and can act as energy currency (ATP) in cells. Some derivatives of nucleotides can function in oxidation-reduction reactions in the cell. 

Proteins are polymers of amino acids that are linked by peptide bonds. All amino acids contain an amino group (-NHj) and a carboxyl group (-COOH). Dipeptides are formed when two amino acids are joined together by peptide bonds. Several covalently linked amino acids are referred to as polypeptides. Proteins can have one or more polypeptides. 

In cells, proteins are present as structural proteins or catalytic proteins (enzymes). Structural proteins are a part of cell membranes, walls, and cytoplasmic components. The primary structure of a protein is determined by its amino acid sequence, and the folding decides its functional ability within the cell. Denaturation of proteins can be caused by extreme conditions, such as pH, heat, or chemical reagents, which affect the folding properties. 

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Biochemistry examines the chemistry of molecules involved in life. These range from small molecules such as carbohydrates to large molecules such as DNA. Much of the chemistry of biological molecules is organic reactions, and so its place within this book is logical. 

J. Wyman and S. J. Gill, Binding and Linkage. Functional Chemistry of Biological Molecules. University Science Books, Mill Valley, CA 1990. 

Figure 6-5 Schematic representation of gel-fiftration column chromatography. (Modified from Bennett TP Graphic biochemistry, vol I, Chemistry of biological molecules. New York Macmillan, 1968.)...

Water-insoluble enzymes have now been developed very few references bear dates prior to 1960, and yet the overall principle of attachment of an enzyme to an insoluble matrix is simple and simulates the natural mode of action and environment of enzymes embedded in biological membranes. The insolubilization of enzymes with retention of activity has already made an impact on the chemistry of biological molecules and systems, and, for an essentially new-born subject, a> large number of reviews dealing with their preparation have been published. " ... 

In the past several decades there have been considerable efforts to develop spectroelectrochemical techniques and these have proved to be an effective approach for studying the redox chemistry of biological molecules. In addition to traditional electrochemical techniques, spectroelectrochemical techniques are used routinely to measure molecular properties such as molecular absorptivities, vibration and electronic spectra, and electronic or magnetic resonance spectra. 

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