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Journal of Medicinal Plants Research Vol. 6(6), pp. 932-933, 16 February, 2012 Available online at http://www.academicjournals.org/JMPR DOI: 10.5897/JMPR11.494 ISSN 1996-0875 ©2012 Academic Journals Review Enzymes: A review M Akram1*, Ejaz Muhiuddin2, Afzal Ahmed3, Shahab-uddin1, Khan Usmanghani4 and Syed Muhammad Ali Shah5 1 Department of Basic Medical Sciences, Faculty of Eastern Medicine, Hamdard University Karachi, Pakistan. Department of Surgery and Allied Sciences, Faculty of Eastern Medicine, Hamdard University Karachi, Pakistan. 3 Department of Medicine and Allied Sciences, Faculty of Eastern Medicine, Hamdard University Karachi, Pakistan. 4 Department of Pre-Clinical Sciences, Faculty of Eastern Medicine, Hamdard University Karachi, Pakistan. 5 College of Conventional Medicine, the Islamia University of Bahawalpur, Pakistan. 2 Accepted 23 December, 2011 Enzymes are made of protein that is present in all living organisms. Enzymes convert substrate into products and are biological catalyst. These increase rate of reaction and remain unchanged by chemical reaction. In this review article, clinical significance, regulation and inhibition of enzymes have been elaborated. Key words: Enzymes, function, regulation, inhibition. INTRODUCTION Enzymes are protein specific biological catalyst that accelerates the rate of reaction. Enzymes act on substrate as a result substrate is converted to product. Substrate binds on active site of enzymes that is specific for substrate (Hansen et al., 1990). Enzymes increases or decreases rate of reaction by increasing or decreasing the energy of activation (Amyes et al., 2001). Protein part of enzymes is called apoenzyme and non protein part is known as prosthetic group (Harris et al., 2002). The traditional understanding is that an entirely new complement of digestive enzymes is secreted by the pancreas into the small intestines with each meal (Lerner et al., 1991). This is thought to be necessary because, like food itself, these enzymes are degraded during digestion. In this review, we discuss experiments that bring this point of view into question. They suggest that digestive enzymes can be absorbed into blood, reaccumulated by the pancreas, and reutilized, instead of being reduced to their constituent amino acids in the intestines. This is called an enteropancreatic circulation of digestive enzymes (Stephen et al., 2002). Enzymes and their sources have been given in Table 1. The process of digestion produces glucose, amino acids, glycerol, and fatty acids. The energy in glucose is *Corresponding author. E-mail: [email protected]. Tel: 92-021-6440083. Fax: 92-021-6440079. used to produce ATP via the reactions of glycolysis, cellular respiration, and the electron transport system (Table 2). The body uses amino acids to construct proteins. Excess amino acids can be used to synthesize pyruvate, acetyl CoA, and alpha ketogluterate, which enters the Krebs cycle. Glycerol and fatty acids can be converted to pyruvate and Acetyl CoA and then enter cellular respiration (Kraut, 1988). ENTEROPANCREATIC CIRCULATION OF DIGESTIVE ENZYMES Intact digestive enzymes can be absorbed by the intestine and resecreted by the pancreas. The pancreas, therefore, appears to be able to recycle proteins much as the liver recycles bile salts, although the magnitude of this process remains uncertain (Leibow and Rothman, 1975; Landry et al., 1993). Diabetes mellitus and digestive enzymes Diabetes mellitus is a metabolic disorder due to relative and absolute deficiency of insulin resulting in hyperglycemia and glycosuria. Researchers are searching new drugs that modulate blood glucose concentration through inhibition of the enzymatic breakdown of complex carbohydrates to meal derived Akram et al. 933 Table 1. Enzymes and their sources. Enzyme Chymotrypsin Trypsin Papain Bromelain Source It is a proteolytic enzyme crystallized from an extract of the pancreas gland of the ox. It is a proteolytic enzyme also crystallized from an extract of the pancreas gland of the ox. It is derived from the green papaya fruit. It is extracted from the pineapple. Because of the relative value of the fruit. Table 2. Clinical significance of enzymes. Enzymes Aspartate aminotransferase Alanin amino transferase Amylase Lactate dehydrogenase Acid phosphatase Alkaline phosphatase Lipase Glutathione reductase Isocitrate dehydrogenase glucose absorption. Acarbose is prescribed in diabetes mellitus mellitus. It inhibits α-glucosidase and as a result disaccharides and polysaccharides cannot break in glucose. Many herbal extracts have been found to posses similar inhibitory effects. Some herbal drugs have similar activity and are proved effective in treatment of diabetes mellitus. Ginger (Zingiber officinale Roscoe) has developed a reputation in treatment of several diseases. In vitro enzymic inhibitory effect of Z. officinale was evaluated in a study. In this study, Z. officinale extract and Acarbose was investigated for their efficacy to inhibit enzymes α -amylase and α glucosidase. These two were allowed to react with cooked rice and percentages of glucose content were measured. The glucosidase and amylase activities on the rice were inhibited by addition of ginger cause significant reduction in glucose percentages which showed comparable results with Acarbose on glucosidase activity. This study indicates ginger can be used as an amylase and glucosidase inhibitor in carbohydrate digestion (Abeysekara et al., 2007). Withania somnifera: A novel source of asparaginase. In one study, various plants were screened for L asparaginase enzyme. W. somnifera was identified as potential source of the enzyme on the basis of high specific activity of the enzyme. The enzyme was purified and characterized from W. somnifera, a popular medicinal plant in Unani system of medicine. It was the first report for L-asparaginase from W. somnifera. Asparaginase is commonly used for treatment of acute lymphocytic leukemia and mast cell tumor, therefore, W. somnifera can be a potential plant based therapy for these disorders (Vishal et al., 2009). Clinical interpretation Myocardial infacrtion Viral hepatitis Pancreatitis Myocardial infarction Metastatic carcinoma Obstructive liver disease Pancreatitis Hepatitis Liver disorders CONCLUSION Enzymes are biological catalyst. They are utilized for digestive purposes as well as in cellular functions. They are also important in diagnosis of disease because in some diseases enzymes, concentration increases that is, indicative of specific disease. REFERENCES Abeysekara W, Chandrasekara A, Liyanage P (2007). Amylase and glucosidase enzyme inhibitory activity of ginger (Zingiber officinale Roscoe) an in vitro study, Trop. Agric. Res., 19: 128-135. Amyes TL, O’Donoghue AC, Richard JP (2001). Contribution of phosphate intrinsic binding energy to the enzymatic rate acceleration for triosephosphate isomerase. J. Am. Chem. Soc., 123(11): 325– 326. Hansen DE, Raines RT (1990). Binding energy and enzymatic catalysis. J. Chem. Edu., 67: 483–489. Harris TK, Turner GJ (2002). Structural basis of perturbed pKa values of catalytic groups in enzyme active sites. IUBMB Life, 53: 85–98. Kraut J (1988). How do enzymes work? Science, 242: 533–540. Landry DW, Zhao K, Yang GXQ, Glickman M, Georgiadis TM (1993). Antibody degradation of cocaine. Science, 259: 1899–1901. Lerner RA, Benkovic SJ, Schulz PG (1991). At the crossroads of chemistry and immunology: catalytic antibodies. Science, 252: 659– 667. Leibow C, Rothman SS (1975). Enteropancreatic circulation of digestive enzymes, Sci., 189(4201): 472-474. Stephen R, Charles L, Lois I (2002). Conservation of Digestive Enzymes, Physiol. Rev., 82(1): 11-18. Vishal P, Shraddha D, Pritesh P (2009). Withania somnifera L. (Ashwagandha): A novel source of L asparaginase, J. Integ. Plant. Biol., 51(2): 201-206.