食品专业英语 LESSON 6 Nomenclature And Definition Of Enzymes

食品专业英语 LESSON 6 Nomenclature And Definition Of Enzymes Enzymes are complex globular protein catalysts that accelerate chemical reaction rates by factors of 1012-1020 over that of uncatalyzed reactions at temperatures around 37℃.By contrast, industrial catalysts inorganic substances are orders of magnitude less effective than enzymes under comparable conditions. For example the reduction of hydrogen peroxide catalyzed by cataloes ,occurs 10 million times faster than it does when catalyzed by colloidal platinum at 37℃. The catalytic efficiency of enzymes is very high, whereby one molecule of enzymes can trans as many as 10,000-1,000,0000 molecules of molecule of substrate per minute. it is this catalytic efficient of enzymes at low temperature which makes them important to the food scientism. This means that foods can be processed or modified by enzymes at moderate temperature ,say 25-50℃,where food products would not otherwise undergo changes at a significant rate .It also means, however, that endogenous enzymes are active under these conditions as well, and this can be beneficial or deleterious. Furthermore, enzymes because of their tremendous catalytic power and low activation energies are active at subfreezing temperatures and therefore can be important stimulants of degradative reactions in refrigerated or frozen foods. Of course, one basis for heat processing is to denature and inactivate enzymes so that the food is not subjected to continuing enzymes activity. The food scientist must have an understanding of the denaturtion phenomenon in order to properly process foods. Another important aspect of enzymes activity in addition to catalytic power is the specificity of enzymes reactions. Industrial catalysts lack this specificity of reaction, and so cannot be used for modifying specific components of a food system. The specificity of hydrogen ion catalysts, for example, is very broad, whereas many enzymes per only a single function, such as hydrolysis of a single bond or bond type. It is this enzymes specificity, which allows the food scientist to selectively modify individual food components and no affect others. The sensitivity and specificity of enzymes also make them important to the food scientist as analytic tools. Analysis for food constituents in many instances can be simplified using enzymes techniques, which are detailed by berg Meyer, and jailbait. Enzymes nomenclature Over the years, the number of enzymes isolated and characterized has continued to increase at an enormous rate. Previously it was custom for individual who isolated and characterized the enzyme to also name it. However, in many instances the same name. Consequently, the nomenclature for enzymes because so chaotic that the international union of biochemistry instituted a commission on nomenclature and classification of enzymes to prepare a system of nomenclature that has become standard and should be used in enzyme work. Each