In scientific research, industrial and agricultural production and medical practice, enzyme activity assay is often performed. Because body’s functional status, the quality of the product are often reflected in the enzyme content and activity. And these can only be determined through enzyme activity assay, so enzyme activity assay has important theoretical and practical significance. Such technique has been widely used in clinical diagnosis.
Enzymes are synthesized in the cells. A variety of tissue cells have their own enzymes to reflect their characteristics, and few enzymes will exudate cells under normal circumstances. However, when the body is diseased, these enzymes’ activity in tissues and fluids changes. Therefore, identification of these enzymes’ activity can be used as a reference for early diagnosis, differential diagnosis, and prognosis. Taking the enzyme activity in the body fluid for example, reasons for its changes are as follow: A. Tissue lesions lead to disruption of membrane balance, glutamic oxalacetic transaminase (GOT) has the highest content in the myocardium, but in the case of myocardial infarction, cell permeability is increased, thus the patient’s serum GOT significantly increased up to 10 times more. B. Cytopathic causes synthetic dysfunction, for example, a lecithin cholesterol transacylase (LCAT) called as “plasma-specific enzyme,” is synthesized in hepatocytes, and then secreted into the blood. Hepatitis patients with decreased enzyme synthesis, and therefore its level in serum is lower than normal. C. Diseases lead excreted obstruction to the secretion of enzymes. The enzyme turns into the blood, so the levels of enzyme activity in serum change. Such as obstructive jaundice or cancer metastasis to the liver to block the bile duct, so the alkaline phosphatase in serum is increased. D. Drugs directly affect enzyme activity, such as organic phosphorus can irreversibly inhibit serum acetylcholinesterase.
Enzyme for clinical diagnosis has some reference value, but there is a fundamental problem-the low specificity. For instance, serum amylase is often used as a diagnostic marker for acute pancreatitis. However, diseases such as salivary gland inflammation, acute parotitis, perforation meningitis and especially duodenal ulcer may cause elevated serum amylase. Solutions: A. Further search for tissue specific enzymes. B. Determination of isoenzyme zymogram, although some enzymes are not tissue-specific, the same enzyme in different tissues tends to emerge as different isozyme zymogram, which can be identified by electrophoresis; C. Enzymatic comparison, or simultaneous determination of two or more enzymes, or blood enzymes and urine enzyme comparison. For example, simultaneous determination of GOT / GPT; serum amylase in the early acute pancreatitis increased and urine enzyme decreased in the late stage; and chronic pancreatitis, pancreatic cancer is mainly reflected on the changes of urine enzyme.
The development of enzyme activity assay: A. easy to perform. To make a variety of identification test strips, such as 2,3,4-triphenyltetrazole impregnated paper, can be used as bacteria identification test paper, which presents red color with bacterial reductase. Bacteria pollution situation can be determined according to its color change. B. Automation, which is especially important when a large number of assays are required. The whole automated processes, including loading, reaction, detection of data. The former type of detector can detect about 1,200 samples per hour.
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