en بیوتکنولوژی Biotechnology پژوهشي Original Research <p>The main purpose of this project is investigation of the organophosphorus hydrolase (OPH) enzyme activity in water in oil (w/o) and oil in water (o/w) creams and investigation of the OPH enzyme stability in formulated creams<strong>. </strong>OPH enzyme was extracted and purified from strain flavobacterium. The w/o and o/w creams were prepared using different formulations. In order to achieve an emulsion with maximum stability, appropriate percentage of the cream components was selected by studying different formulations and the physical and chemical stability of the produced cream were considered. 5U_enzyme/90g_cream enzyme was used for each formulation. To measure the enzyme activity in creams, extraction method was used and enzyme activity was determined based on parathion hydrolysis. The thermal stability of OPH in both types of w/o and o/w creams was studied at 4 and 30^&nbsp;&deg;C for various time periods. The average enzyme activity was about 0.0065 U/g_cream and 0.018 U/g_cream for w/o and o/w creams respectivly. According to the results, the relative activity at 4 &deg;C was reduced to 50% after 26 and 45 days in w/o and o/w creams, respectivly. The results showed that the OPH enzyme activity in o/w cream was 2.6 times more than that of w/o cream, because of the higher hydrophobicity of o/w cream compared to w/o. The OPH enzyme stability in o/w cream was greater in comparison to w/o cream. The OPH enzyme was active for nearly 2 months on o/w creams at 4 &deg;C .</p> Creams, organophosphorus hydrolase, enzyme stability 75 83 http://pbr.mazums.ac.ir/browse.php?a_code=A-10-71-2&slc_lang=en&sid=1 Mariye Rajaie 10031947532846003861 10031947532846003861 No Department of Bioscience and Biotechnology, Malek Ashtar University of Technology, Tehran, Iran Seyed Morteza Robatjazi 10031947532846003862 10031947532846003862 Yes Department of Bioscience and Biotechnology, Malek Ashtar University of Technology, Tehran, Iran Hamid Akbari 10031947532846003863 10031947532846003863 No Department of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran Sanaz Mahboudi 10031947532846003864 10031947532846003864 No Department of Bioscience and Biotechnology, Malek Ashtar University of Technology, Tehran, Iran Jafar Mohammadian Mosaabadi 10031947532846003865 10031947532846003865 No Department of Bioscience and Biotechnology, Malek Ashtar University of Technology, Tehran, Iran