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Öğe Dyeing of wool fibres with natural dyes: Effect of proteolytic enzymes(Taylor & Francis Inc, 2006) Dogru, M; Baysal, Z; Aytekin, CIn spite of the widespread use of proteins (casein, peptone, etc.) and protein fragments as a substrate for the proteolytic enzymes, a substrate prepared from dyes that adsorb onto appropriate materials, such as wool and cotton, are also used for enzyme activity determination. In the point of view of this thought, it was our aim to develop the substrates which are easily and economically obtainable and also environmentally safer for the frequently used proteolytic enzymes, such as subtilisin carlsberg, trypsin, chymotrypsin, and protease type XVI and, if possible, to prepare the specific substrate at least for one of these enzymes. For this aim, wool was dyed with natural dyes such as juglone, lawsone, berberine, and quercetin. The optimum pH, incubation time, and agitation rate were determinated. The results indicate that, of all the tested enzymes on wool-dye complex as an insoluble subtrate, the most appropriate complex was found to be wool-lawsone complex.Öğe Effect of proteolytic treatment on dyeing of casein with synthetic dyes(Asian Journal Of Chemistry, 2006) Dogru, M; Baysal, Z; Aytekin, ÇThe activity of proteolytic enzymes is commonly measured using casein as a substrate. Modified caseinolysis assay was developed with synthetic dyes such as procion red, procion yellow and procion blue for subtilisin carlsberg, protease type XVI, trypsin, chymotrypsin, respectively. Optimum pH, incubation time were determined. K-M, V-max and k(cat)/K-M values were also determined for these enzymes. The results indicate that the effect of all the tested enzymes on the synthetic dye-casein complexes; the most appropriate complex was found to be procion yellow.Öğe Proteolytic activity of commercial subtilisin from genus Bacillus on some animals milk caseins(Mbr Press Inc, 1997) Aytekin, C; Kaya, Z; Dogru, MCasein is a non-specific substrate for the all proteases. In this study casein was purified from cow, water buffalo, sheep and goat milk and used as a substrate for subtilisin purified preparations from genus Bacillus. On the basis of K-M and V-max value we can say that cow milk casein is the best substrate for the enzyme compared to other animals milk caseins. On the other hand, we have investigated the possible relationship between the Ca2+ and (PO4)(3-) content of casein and the casein appropriate for the enzyme. The cow milk casein with lowermost Ca2+/(PO4)(3-) ratio suggests that these ions may have an influence on enzyme-substrate interaction. Although this enzyme is active in the pH range of 7-11 and a temperature range of 25-60 degrees C, the optimal pH and temperature for the enzyme against cow milk casein were found to be 10,0 and 37 degrees C respectively.Öğe Purification and some characterization of an extracellular ?-amylase from a thermotolerant Bacillus subtilis(Springer, 2003) Uyar, F; Baysal, Z; Dogru, MExtracellular alpha-amylase from Bacillus subtilis was purified by ion-exchange chromatography and gel filtration. The molecular weight was determined to be 48.000. Various metal ions inhibited alpha-amylase activity even at low concentrations (5 mM). Ca2+, Ba2+, m,(2+) and Ni2+ were mild inhibitors, whereas Zn2+, Fe2+, Pb2+, H2+ Mg2+, Cd2+ and Cu2+ were potent inhibitors. The activity of the enzyme was reduced by Ca2+ at high concentrations but increased at 2.5 mM. Ethylenediaminetetraacedicacid (EDTA) also affected the enzyme activity even when compared with Ca2+ ions at low concentrations. Calcium and EDTA showed dose-dependent inhibition. Different enzyme solution containing Ca2+, Ba2+ and Mg2+ (2.5 mM and 10 mM) was added 2.5 mM EDTA and enzyme activity increased at 10 mM metal ions concentrations. The K-m and V-max values for alpha-amylase were found to be 2.2 x 10(-4) g mL(-1) and 0.020 U mL(-1), 2.91 x 10(-4) g mL(-1) and 0.016 U mL(-1), 4.04 x 10(-4) g mL(-1) and 0.021 U mL(-1) for starch, amylose and glycogen. respectively.Öğe Suitability of animals' purified milk caseins and their subunit ?-caseins as substrates for subtilisin and trypsin(Marcel Dekker Inc, 2001) Dogru, M; Baysal, Z; Aytekin, ÇAcid casein and K-casein were purified from different species of animal's milk, such as cow, sheep, goat, and water buffalo. These caseins were used as substrates for commercially available subtilisin and trypsin. It was established that, when acid caseins were used as a substrate for subtilisin, cow acid casein was found to be a better substrate for the enzymes, compared to other animals' milk casein. It was suggested that this acid casein has significantly more aromatic amino acids, as compared to arginine and lysine. K-m and V-max values, which were obtained for cow K-casein, showed that cow K-casein was a better susbstrate for trypsin than the others, suggesting that cow Ic-casein has a rich content of lysine, arginine, and aromatic amino acids by comparison with the others. The calculated C/N ratio also supports this suggestion.Öğe Use of natural dye-casein complexes(Taylor & Francis Inc, 2006) Dogru, M; Baysal, Z; Aytekin, Ç; Aydin, HThe activity of proteolytic enzymes is commonly measured using casein as a substrate. A modified caseinolysis assay was developed with natural dyes such as juglone, lawsone, berberine, and quercetin for Subtilisin carlsberg , protease type XVI, and trypsin, respectively. The pH dependence and incubation time were determined. K-m, V-max, and k(cat)/K-m values were also determined for these enzymes. Lawsone was found to be a better substrate than the others.
