Enzymes plays a vital role in catalyzing biochemical reactions reaction which are necessary for normal human growth,maturation and reproduction.
Diagnostic enzymology involves the measurement of enzymes activities in body fluids in order to diagnose a disease.In most cases,serum or blood are the most useful samples used although urine,cerebrospinal fluid and extracellular fluids are sometimes needed.
Most enzymes used for diagnostic purposes have no direct physiological role in the blood.Their natural presence under normal circumstances is as a result of natural ageing and turn over of living cells.
High level of enzymes in blood can indicate increase cellular turnover (increase enzymatic activity) and necrosis caused by disease.Important and largely overlooked cause of high enzyme level in blood is tissue synthesis of new enzymes that occur in response to disease,induction by various drugs and carcinogenesis for examples in obstructive liver disease,hepatic Alkaline Phosphatase is increased largely because of increase synthesis due to abnormal intracanalicular pressure.Phenobarbital and several other drugs induce microsomal enzyme production that lead to increase production or synthesis of Gamma glutamyl transpeptidase
Enzyme Kinetics (Lock and Key Method)
Enzymes (E) are biological catalysts that combine with substrate (S) to form intermediate complexes (ES) leading to the formation of products (P) and restoration of the original enzyme.Reaction involving one substrate exhibit the following kinetic
Some enzymes catalyze more complexe reactions in which there are two or more substrates that form multiple productions.The reactions is a function of several factors including;
- Substrates and enzyme concentration
- Presence of cofactors
- Presence of coenzymes
- Presence of inhibitors or inhibition
Empirical observation shows that the rate or reaction velocity is proportional to substrate concentration at relatively low values
In diagnostic enzymology,the goal is the measurement of the activity or the concentration of the enzyme itself.Therefore,test condition such that the reaction rate will depend only on the concentration of the enzyme present in the sample to be measured.The substrate concentration should be made sufficient and all other factors that influence the reaction rate should be optimized and controlled.
How to calculate enzymes activity
Enzyme activity can be expressed either in international unit per litre (Ul) or nanokeital per liltre (nkat/l).Because Beer’s lambert law states that ‘’ Concentration is directly proportional to absorbance”,Enzyme activity each be determined from the change in absorbance per unit time
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