12th ICB and 4th ICBMB (Abstracts of the 12th Iranian Congress of Biochemistry and 4th International Congress of Biochemistry and Molecular Biology, Mashhad, Iran, September 6-9, 2011) Protein Chemistry and Enzymology E Poster – [A-10-9-1] Molecular mass determination, effect of metal ions and chemical modification on chickpea seed's beta-d-galactosidase Aberumand Mohammad a , Bideh Shabhana b a Ahwaz Jondishapou University of Medical Sciences, Ahvaz, Iran b India Pune University, Dept. of Biochemistry, India E-mail address: aberumand@yahoo.com (A. Mohammad) Previous studies from this laboratory have identified β-d-galactosidase from chickpea seeds. This enzyme was purified to 1338.6 folds. The purpose of the present study was to determine the molecular mass, effect of metal ions and chemical modification on chick pea seed's β-d- galactosidase. Based upon SDS-PAGE analysis, β-d-galactosidase was a homodimer with molecular weight of 15.600 Daltons. Ag+2 had inhibitory effect on β-galactosidase. Chemical modification studies revealed involvement of tryptophan in enzyme activity. Keywords: β-d-galactosidase, Molecular mass and chemical modification doi:10.1016/j.clinbiochem.2011.08.187 E Poster – [A-10-81-2] Determination of the inhibitory mechanism of eugenyl adamantate on 15-lipoxygenase Sadeghian Hamid a , Jabbari Atena b , Davoodnejad Mahdieh a , Alimardani Maliheh a , Shakeri Sepideh a a School of Paramedical Sciences, Department of Laboratory Sciences, Mashhad, Iran b School of Sciences, Department of Chemistry, Iran E-mail address: sadeghianh@mums.ac.ir (S. Hamid) Introduction: Lipoxygenases are one of the non haem iron- containing proteins with ability of unsaturated lipid peroxidation in animals and plants. The critical role of the enzymes in formation of inflammations, sensitivities and some of the cancers has been demonstrated in mammalians. Importance of the lipoxygenases leads to development of mechanistic studies, product analysis and synthesis of their inhibitors. In this article the inhibitory mechanisms of eugenyl adamantate, a new synthetic potent inhibitor of lipoxygenase is studied. Materials and methods: The lipoxygenase activity of soybean 15- lipoxygenase in the presence of eugenyl adamantate was assayed by using two spectrophotometric methods: conjugated dien formation in 235 nm and DMAB-MBTH peroxide formation in 592 nm. Results: The experiments show that the mentioned compound decreases the lipoxygenase activity in two concentration ranges by 80–120 nM and 5–13 μM. Conclusion: The kinetic studies based on Lineweaver–Burk plot show the mixed inhibitory mechanism for eugenyl adamantate. Keywords: 15-lipoxygenase, Inhibitors, Peroxide formation, DMAB, MBTH doi:10.1016/j.clinbiochem.2011.08.188 E Poster – [A-10-110-1] Inhibitory and destabilizing role of putrescine on yeast alcohol dehydrogenase Darbandsar Mazandarani Samira, Moosavi-Nejad Zahra Department of Biology, Faculty of Basic Science, Alzahra University, Tehran, Iran E-mail addresses: sdarbandsar@yahoo.com (D.M. Samira), nejad@ibb.ua.ac.ir (M.-N. Zahra) Introduction: Alcohol dehydrogenases are present in animal tissues, plants and microorganisms and in yeast. Yeast alcohol dehydrogenase (YADH) plays important roles in ethanol production process, synthesis of enantiomerically pure stereoisomers of chiral alcohols and produc- tion of β-hydroxy acid. YADH are studied for direct fermentation of biomass to ethanol. Unfortunately, YADH has very low thermal stability, limiting industrial use of the enzyme. On the other hand, polyamines have also been implicated in plant responses to abiotic and biotic stress, drought and salt stress, osmotic shock and pathogen infection. In this research, effect of putrescine (as a polyamine) has been investigated on optimum temperature (Topt) activation energy (Ea) of YADH. Materials and methods: To study the effect of putrescine, the reaction mixture contained putrescine (4 mM), enzyme solution and 0.01 M pyrophosphate buffer (pH 8.5). It was incubated for 2 min over different temperatures ranging from 5 to 40 °C. Then ethanol (170 mM) and NAD+ (1.5 mM) were added and then activity was measured by following A340 and compared with control. Results: The results showed that Topt of YADH is about 30 °C. Putrescine shifted the Topt to 20 °C so that YADH activity decreased at higher temperatures. Ea (calculated using Arrhenius plot) was com- pared in the absence and presence of the putrescine. Conclusion: These data suggested an inhibitory role for putrescine via increasing activation energy of YADH enzymatic reaction. 0009-9120/$ – see front matter. Contents lists available at ScienceDirect Clinical Biochemistry journal homepage: www.elsevier.com/locate/clinbiochem Clinical Biochemistry 44 (2011) S86–S124