Waste elimination, enzymes

METABOLISM. The chemical transformations occurring in an organism. from the lime a nutrient substance enters it until it has been utilized and the waste products eliminated In animals and humans, digestion ami absorption are primary steps, followed by complicated series of degradations. syntheses, hydrolyses, and oxidations, in which agents such as enzymes, bile acids, and hydrochloric acid take part. These transformations are often localized with respect to organs, tissues, and types ol cells involved. 

Waste-treatment processes commonly result in the production of solid wastes that must be disposed of safely. Enzymatic treatment is no exception. For example, although enzymatic treatment may not produce as large a quantity of solid products as does biological treatment, some solid residues may be formed, e.g., the polymer precipitates formed during the treatment of phenols with peroxidases, spent adsorbents such as talc, chitin, or activated carbon that are used to eliminate the soluble products of enzymatic reactions, or residues of plant materials such as raw soybean hulls when they are used in place of purified enzymes during treatment. Perhaps, the polymers and adsorbents could be incinerated to recover some energy if the emission of dangerous combustion by-products can be controlled or prevented. The residues of plant materials could potentially be composted and used as soil conditioners, provided that pollutants do not leach from them at substantial rates. To date, none of these disposal problems have been addressed adequately. 

The enzyme-antigen- or enzyme-antibody-linked enzyme immunotissay (EIA) has many advantages over radioimmunoassays (RIA), such tis elimination of expensive counting equipment, elimination of radioactive waste, and cheap and stable reagents (305). The application of electrodes to monitor immunological reactions is described in the following sections. 

In developing some of the elementary principles of the kinetics of enzyme reactions, we shall discuss an enzymatic reaction that has been suggested by Levine and LaCourse as part of a system that would reduce the size of an artificial kidney. The desired result is the production of an artificial kidney that could be worn by the patient and would incorporate a replaceable unit for the elimination of tte nitrogenous waste products such as uric acid and creatinine, In the microencapsulation scheme proposed by Levine and LaCourse, the enzyme urease would be used in tire removal of urea from ti)e bloodstream. Here, the catalytic action of urease would cause urea to decompose into ammonia and carbon dioxide. The mechanism of the reaction is believed to proceed by the following sequence of elementary reactions ... 

Normal growth requires potassium involvement in enzyme activities. It plays a part in making muscle protein from amino acids, assists in the storage of glucose in the hver, and cooperates with sodium in maintaining blood pressure. It helps in the synthesis of nucleic acids and signals the kidneys to eliminate wastes in the urine. Potassium works with sodium to regulate the heartbeat. 

Major disadvantages of the processes mentioned include the current need for economic subsidies, the high cost of enzymes, and the formation of waste streams (such as acid pretreatment materials and toxic compounds found in acidic hydrolysates of biomass), although utmost efforts are being made to eliminate these drawbacks. When biomass is utilized, lignin (approximately 10-40 wt% of biomass) cannot be broken down into fermentable components. Thus, 10 0%... 

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