Biochemistry in living systems

Siik is just one exampie of macromoiecuies, aiso known as poiymers. Macromoiecuies are the subject of this chapter. The principies introduced in Chapters 9-11 help to explain the properties of these molecules, many of which are carbon-based. In this chapter, we outline the principles of the stmcture and synthesis of the major classes of macromoiecuies and describe the properties that give these chemical substances central roles in industrial chemistry and biochemistry. We describe the components from which macromoiecuies are constmcted, some important industrial polymers, and the macromoiecuies found in living systems. 

Structural motifs become especially important in defining protein families and superfamilies. Improved classification and comparison systems for proteins lead inevitably to the elucidation of new functional relationships. Given the central role of proteins in living systems, these structural comparisons can help illuminate every aspect of biochemistry, from the evolution of individual proteins to the evolutionary history of complete metabolic pathways. 

The distinct feature of biochemistry is that it uses the principles and language of one science, chemistry, to explain the other science, biology at the molecular level. Biochemistry can be divided into three principal areas (1) Structural biochemistry focuses on the structural chemistry of the components of living matter and the relationship between chemical structure and biological function. (2) Dynamic biochemistry deals with the totality of chemical reactions known as metabolic processes that occur in living systems and their regulations. (3) Information biochemistry is... 

B. Halliwell, Reactive oxygen species in living systems source, biochemistry, and role in human disease, w.y.A/e /. 9I(3C) (1991)14S-22S. 

Metabolism includes all of the chemical transformations that occur in living systems. A detailed discussion of metabolism is beyond the scope of this chapter and the reader is directed to other comprehensive resources (22). The lesson to impart to all students interested in green chemical design is that fundamental chemical reactions are the foundation of all of biotransformation. Addition reactions, conjugation reactions, substitutions and eliminations occur to chemicals found naturally inside living systems (biochemistry) and to those that are found external to living systems (xenobiotics) as well as in laboratory round-bottom flasks. Table III lists some of the more common biotransformation pathways. 

Aminophosphonic acids play an important role in living systems. The first acid to be found naturally, namely (2-aminoethyl)phosphonic acid (also known as ciliatine, 2AEPH, and jS-Ala ) , has been followed more recently by 2-amino-5-phosphonopent-2-enoic acid, isolated from Streptomyces plumbens, and (2-amino-l-hydroxyethyl)phosphonic acid, isolated from Acanthamoeba castellani and formed through the biological hydroxylation of (2-aminoethyl)phosphonic acid. Many acids are inhibitors of enzymes important in carboxylic acid biochemistry. Ala is a potent inhibitor of a racemase from Gram-positive bacteria (the corresponding phosphinic acid 99 is not). Phosphinothricin... 

There is now a formidable array of sophisticated and powerful electrochemical tools and techniques available to investigate the redox properties of ions and molecules in solution. Probably the most complex and therefore scientifically challenging redox processes occur in living systems. Biochemistry... 

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