Enzyme biochemical molecules

Atomic oxygen attacks and destroys enzymes and other protein molecules, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) molecules, and other essential biochemical molecules, interrupting... 

Except for the property of rotating plane-polarized light in opposite directions, the physical properties of enantiomers of the same compound are identical. In addition, their chemical properties are identical, except when they are acted upon by another chiral molecule. One such kind of molecule consists of enzymes, large molecules of proteins that catalyze biochemical reactions. Therefore, many biochemical reactions involve chiral molecules. 

Hydrolases are hydrolytic enzymes, biochemical catalysts that use water to cleave chemical bonds, usually dividing a large molecule into two smaller molecules. Examples of common hydrolases include esterases, proteases, gly-cosidases, nucleosidases, and lipases. 

Enzyme—Biological molecule, usually a protein, which promotes a biochemical reaction but is not consumed by the reaction. 

Enzyme A molecule that acts as a catalyst, speeding up biochemical reactions. 

Figure 18 A illustrates the basic features of recombinant DNA construction. The process begins by using a restriction enzyme (Biochemical Methods 17.1) that generates sticky ends to cleave DNA from two different sources. The DNA fragments are then mixed under conditions that allow annealing (base pairing) between the sticky ends to occur. Once base pairing has occurred, the fragments are covalently bonded together by DNA ligase. After recombinant DNA molecules...

The cell uses a different strategy. With a series of enzymes, biochemical pathways in the cell carry out a step-by-step oxidation of glucose. Small amounts of energy are released at several points in the pathway and that energy is harvested and saved in the bonds of a molecule that has been called the universal energy currency. This molecule is adenosine triphosphate (ATP). 

Implanted biomaterials or medical devices are subjected to the surrounding host environment, which contains biochemical molecules such as enzymes [41,42], free radicals, peroxides [43], and hydrogen ions secreted by inflammatory cells and infecting microbes [44-46], The phagocytic mechanism of inflammatory cells such as neutrophils and macrophages has naturally evolved as a defense strategy for the body to ensure the removal of undesired foreign objects. Therefore, the potent biochemical actions of the secreted species can result in the unintended breakdown of solid-phase polymeric components of implanted devices over an extended period of time (months or years) [45],... 

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 ... 

Enzyme Protein molecule that mediates a specific biochemical conversion. 

The presence of a catalyst. Catalysts are agents that increase reaction rates without being used up. They affect the kinds of collisions (the mechanism) that lead to reaction. Catalysts play a crucial role in our lives. The physiology of most living species depends on enzymes, protein molecules that act as catalysts, increasing the rates of selected biochemical reactions. 

Enzymes Protein molecules that catalyze the various biochemical reactions. 

Basic to understanding the process of metabolism, is the realization that all of the reactions are catalyzed by enzymes—protein molecules which speed up biochemical reactions without being used up in the reactions. Furthermore, most all of the biochemical reactions of the metabolic processes are reversible. This is an important concept. 

Pahner, J. L. Johnson, J. B. Timmerman, M. W. Method, system and devices for the oxygen-independent enzymic assay and detection of biochemical molecules. Eur. Pat. Appl. EP 330517, 1989 Chem. Abstr. 1990,113, 111981. 

Another category of catalyst is the type present in the human body or any other biological system. Biological catalysts found in living organisms are usually large protein molecules called enzymes. Biochemical reactions operate within a relatively... 

This means that the methods developed for the calculation of physicochemical effects can also be used to deepen our understanding of biochemical rcaaions. Clearly, electronic effects within the substrate molecule arc not the only ones determining its reactivity, The binding of the substrate to the enzyme is also influenced... 

Potcntiomctric Biosensors Potentiometric electrodes for the analysis of molecules of biochemical importance can be constructed in a fashion similar to that used for gas-sensing electrodes. The most common class of potentiometric biosensors are the so-called enzyme electrodes, in which an enzyme is trapped or immobilized at the surface of an ion-selective electrode. Reaction of the analyte with the enzyme produces a product whose concentration is monitored by the ion-selective electrode. Potentiometric biosensors have also been designed around other biologically active species, including antibodies, bacterial particles, tissue, and hormone receptors. 

The development of malathion in 1950 was an important milestone in the emergence of selective insecticides. Malathion is from one-half to one-twentieth as toxic to insects as parathion but is only about one two-hundredths as toxic to mammals. Its worldwide usage in quantities of thousands of metric tons in the home, garden, field, orchard, woodland, on animals, and in pubHc health programs has demonstrated substantial safety coupled with pest control effectiveness. The biochemical basis for the selectivity of malathion is its rapid detoxication in the mammalian Hver, but not in the insect, through the attack of carboxyesterase enzymes on the aUphatic ester moieties of the molecule. 

Entrapment of biochemically reactive molecules into conductive polymer substrates is being used to develop electrochemical biosensors (212). This has proven especially useful for the incorporation of enzymes that retain their specific chemical reactivity. Electropolymerization of pyrrole in an aqueous solution containing glucose oxidase (GO) leads to a polypyrrole in which the GO enzyme is co-deposited with the polymer. These polymer-entrapped GO electrodes have been used as glucose sensors. A direct relationship is seen between the electrode response and the glucose concentration in the solution which was analyzed with a typical measurement taking between 20 to 40 s. 

This chapter lists some representative examples of biochemicals and their origins, a brief indication of key techniques used in their purification, and literature references where further details may be found. Simpler low molecular weight compounds, particularly those that may have been prepared by chemical syntheses, e.g. acetic acid, glycine, will be found in Chapter 4. Only a small number of enzymes and proteins are included because of space limitations. The purification of some of the ones that have been included has been described only briefly. The reader is referred to comprehensive texts such as the Methods Enzymol (Academic Press) series which currently runs to more than 344 volumes and The Enzymes (3rd Edn, Academic Press) which runs to 22 volumes for methods of preparation and purification of proteins and enzymes. Leading referenees on proteins will be found in Advances in Protein Chemistry (59 volumes. Academic Press) and on enzymes will be found in Advances in Enzymology (72 volumes, then became Advances in Enzymology and Related Area of Molecular Biology, J Wiley Sons). The Annual Review of Biochemistry (Annual Review Inc. Patio Alto California) also is an excellent source of key references to the up-to-date information on known and new natural compounds, from small molecules, e.g. enzyme cofactors to proteins and nucleic acids. 

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