49 Himalayan Journal of Applied Medical Sciences and Research Research Article Antitumor Activity of Arginine Deiminase Purified From Klebsiella Pneumonia Essmaa Hussein Gutef University of Wasit / Iraq, College of Dentistry, Department of Basic Scince INTRODUCTION Enzymes operate as biocatalysts, assisting metabolic and biological reactions (Nigam,2013). Because microorganisms can be cultivated in large numbers in a short amount of time and genetic changes can be made to microbial cells to increase enzyme production, they are the primary source of enzymes.Because Arginine can be generated from citrulline by the urea cycle enzymes argininosuccinatesynthetase and argininosuccinatelyase. 2 steps, it is an amino acid that is not required for life mice and humans ( Asciertoet al., 2015). Argininosuccinatesynthetase converts aspartic acid and citrulline to argininosuccinate. Argininosuccinatelyase converts arginine and fumaric acid from argininosuccinate. (Delageet al.,2018). The ADI pathway for arginine metabolism is extremely common in a variety of bacteria allowing them to adapt to difficult environmental niches as well as host defenses(Xionget al.,2014 andChoi et al., 2012 ). Arc operons genes arcA,arcB, and arc C (Ryan et al., 2009) encode a mechanism (Ryan et al., 2009) Ammonia, CO2, and ATP are produced as byproducts of the digestion of arginine to ornithine. (Nováket al., 2016). Growing biotechnological advances reveal that cancer cells use a different metabolic route to maintain higher proliferation rates of cell death and the ability tolerating some signs of cell death (Tennant et al., 2010). Treatments for peptides & proteins dependent on targeted metabolism regulationare presently in use around the world, and several are undergoing clinical trials (Changou et al., 2014). In recent decades, the arginine deiminasehas been frequently used in targetingdrug chemotherapeutic for hepatic carcinoma cells (HCC) and skin malignancies. (Yoon et al., 2012). The lack of expression of argininosuccinatesynthetase in tumor cells contributes to ADI's anti-cancer activity, especially arginine auxotrophic cancer cells, preventing them from synthesizing their own arginine. They do, however, need a lot of arginine to develop quickly. The circulatory system's L-arginine is hydrolyzed into L-citrulline and ammonia when ADI is given as a chemotherapeutic treatment (Wang and Li, 2014). A lack of arginine impairs protein, Cell death is caused by cell growth stop in the G0 phase and G1 phase of cell development, which results in RNA andDNA synthesis(El-Sayedet al., 2015). *Corresponding Author ESSMAA HUSSEIN GUTEF Article History Received: 10.01.2023 Accepted: 20.01.2023 Published: 07.02.2023 Citations: Essmaa Hussein Gutef. (2023): Antitumor activity of arginine deiminase purified from Klebsiella pneumonia. Hmlyn Jr Appl Med Scie Res, 4(1), 49-53 Abstract: The goal of this research was to characterize ADI isolated from Klebsiella pneumonia and investigate its antitumor efficacy in vitro. Because the arginine- degrading enzyme is a potent anticancer agent, the enzyme was purified from Klebsiella pneumonia clinical isolate in tow steps: precipitation with 70% saturated Ion exchange chromatography with DEAE-cellulose column and ammonium sulphate. The most active fractions in enzyme activity (4 U/ ml), With 6.4 folds of purifying and 57.6% enzymes recovery, the functional group of enzyme extract was 40 U/mg, The cytotoxic activity of purified arginine deiminase on HepG2, MCF-7 and WRL68 cells for 24 was examined. The growth of bacteria was found to be reduced by purified arginine deiminase. cancer cell line MCF-7and HepG-2 with an IC50 of142.6ϻg /ml and 64.10ϻg/ml respectively. At a concentration of 6.25 ϻg/ml, 94.21% and 94.79% cell viability were observed of MCF-7and HepG-2 after treatment with purified arginine deiminase, respectively. while, cell viability reached to 41.01% and 48.23% using 400ϻg/ml concentration purified arginine deiminase, respectively While ADI didn't show a significant effect on the viability of normal cell line. Keywords: Arginine Deiminase, Klebsiella Pneumonia. Open Access