Enzymes are biological catalysts that are vital to living organisms. Without enzymes, the process of turning the food an organism eats into energy that can be used to keep its cell functioning, for example, would be impossibly slow. It is not known how many enzymes exist; more than 1,000 have been listed and many more doubtless await discovery.
Those enzymes that have been isolated and identified in a pure state have proved to be proteins, and although most enzymes have not been positively identified as proteins, those conditions and substances that denature, or precipitate, proteins also inactivate enzymes. Some of these conditions and substances are extremes of acidity or alkalinity, the salts of heavy metals, ultraviolet light, and high temperatures. Most catalytic reactions speed up when heat is applied, and enzyme-assisted reactions are no exception. If the cell is heated, the reaction speeds up until the optimum temperature is reached. If the cell gets any hotter, the enzymes become progressively inactive and the reaction slows until eventually, at about 120°F (50°C), enzymes are completely denatured. The optimum temperature in the human body is between 86 and 104°F (30–40°C). Within this range, there is a maximum reaction speed at which no damage to the enzymes occurs. The destruction of enzymes at high temis probably one reason that a prolonged raised body temperature, as in a fever, can prove fatal.
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PROTEIN PRODUCTION |
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33 Yeast enzymes, when fermented, can produce bacterial protein as an end result. Here, yeasts are grown in a preparation containing methanol (produced from natural gas), water, phosphoric acid, sodium, potassium, magnesium, and various trace ingredients. After sterilization, the yeasts pass through an oxygen-rich fermenter vessel containing air and ammonia. Fermentation produces the bacterium Methylophilus methylotrophus, which is then dried, resulting in a protein-rich animal food.
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Enzymes promote the chemical processes collectively called metabolism. There are two aspects to metabolism: anabolism, which is the synthesis of complex molecules from simple ones, and catabolism, which is the degradation, or breaking down, of large molecules into simpler ones. The enzymes concerned in these processes may be classified in the following way: transferases transfer a substance from one molecule to another; isomerases rearrange molecules; lyases split complex substances into simpler ones; hydrolases act like lyases but use water in the reaction; ligases or synthetases are concerned with the synthesis of substances; and oxidoreductases are concerned with oxidizing and reducing substances.
Enzymes, unlike other catalysts, are specific—each is concerned with only one reaction and acts only upon a particular substrate. For example, the enzyme maltase is involved only in converting its substrate maltose into glucose. There are a few that act on more than one substrate, but even these take part in a limited range of reactions. The actions and interactions of enzymes are complex, and the absence of just one enzyme in the body can have catastrophic results for health.
There are many instances in which a large number of enzymes are required to maintain health. Any imbalance in these enzyme combinations, either because of over-production or deficiency, will upset the metabolism and can cause a chain of disorders.
