Biologic systems enzymes

Table 1.6 Metals in Biological Systems Enzyme Catalysis...

Note that the most important function of the catalyst, here and in many other instances, is not so much its overall catalytic activity as its selectivity in promoting the one reaction (9.12) over its competitors. In biological systems, enzymes have evolved to extraordinary degrees of selectivity often, they will catalyze one specific biochemical reaction and no others. 

The results of animal tests of the types described above with delta-1-THC, delta-6-THC, and other cannabinoids have been shown to parallel activity in man (Hollister 1974). Hence, we assume that the results with (32) and (33) likewise indicate parallel activity in man. If this correct, cannabimimetic activity in man has a strict stereochemical requirement, which indicates a probable interaction with a chiral biological system (enzyme, receptor site, etc.) and not just an unspecific action due to the high lipid solubility of the cannabinoids. 

Coupled reactions play a crucial role in our survival. In biological systems, enzymes facilitate a wide variety of nonspontaneous reactions. For example, in the human body, food molecules, represented by glucose (C6Hx206), are converted to carbon dioxide and water during metabolism with a substantial release of free energy ... 

Activation energy. The minimum energy required to carry out the reaction is called the energy of activation, E. If a reaction requires higher activation energy, the rate of reaction is lowered. The presence of a catalyst lowers the activation energy and increases the rate of reaction. In biological systems, enzymes act as catalysts. 

What we have seen is, that enzymes are highly specific catalysts in biological systems. Enzymes are catalytic proteins, they represent the most efficient class of catalysts. Their active site can, for example, be a carboxylic or an amino group, embedded in a specific geometry. Several weak interactions (electrostatic, H-bonds, van der Waals) help in establishing the highly specific manner in which a substrate mulecule binds to the active site. 

Disaccharides are not used directly in the body but are first hydrolyzed to monosaccharides. Disaccharides yield two monosaccharide molecules when hydrolyzed in the laboratory at elevated temperatures in the presence of hydrogen ions (acids) as catalysts. In biological systems, enzymes (biochemical catalysts) carry out the reaction. A different enzyme is required for the hydrolysis of each of the three disaccharides ... 

Coming from biological systems, enzymes have to be compatible with biological systems and are therefore generally not toxic or chemically hazardous. 

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