Читать книгу Encyclopedia of Renewable Energy - James Speight G., James G. Speight - Страница 141

A biocatalyst is a catalyst (such as, for example, an enzyme) that is of biological origin. Thus, biocatalysis is the use of natural catalysts, such as protein enzymes, to perform chemical transformations on organic compounds. Both enzymes that have been more or less isolated and enzymes still residing inside living cells are employed for this task. More than one hundred years ago, biocatalysis was employed to achieve chemical transformations on non-natural man-made organic compounds, and the last 30 years have seen a substantial increase in the application of biocatalysis to produce fine chemicals, especially for the pharmaceutical industry.

Biocatalysts are living (biological) systems that increase the rate of chemical reactions. In biocatalytic processes, natural catalysts, such as enzymes, perform chemical transformations of organic compounds. In fact, enzymes that have been isolated as separate molecular entities as well as enzymes still remain inside living cells are employed as catalysts that can catalyze novel small molecule transformations that may be difficult or impossible using classical synthetic organic chemistry. In addition, enzymes are environmentally benign insofar as they can be completely degraded in the environment.

Biocatalysts do not operate by different scientific principles from organic catalysts. The existence of a multitude of enzyme models including oligopeptide or polypeptide catalysts proves that all enzyme action can be explained by rational chemical and physical principles. However, enzymes can create unusual and superior reaction conditions such as extremely low pKa values or a high positive potential for a redox metal ion. Enzymes have increasingly been found to catalyze almost any reaction of organic chemistry. Moreover, the notion that biocatalysts are slow catalysts is false and optimized syntheses not only produce high selectivity or total turnover numbers but also satisfactory-to-high yields of products.

See also: Enzymes.