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    6-phosphogluconate dehydrogenase: Purification, characterization and kinetic properties from rat erythrocytes
    (Tubitak Scientific & Technological Research Council Turkey, 2004) Beydemir, O; Çiftçi, M; Yilmaz, H; Küfrevioglü, OI
    In this paper, a simple and rapid method for the purification of 6-phosphogluconate dehydrogenase from rat erythrocytes together with an analysis of the kinetic behavior and some properties of the enzyme are considered. The purification steps comprised high-speed centrifugation, 20-50% ammonium sulfate precipitation and 2', 5'-ADP Sepharose 4B affinity gel chromatography. The yield was 78.4% and the specific enzyme activity was 5.15 EU/mg proteins. The molecular mass of the subunit was estimated to be 59,566 Da by SIDS polyacrylamide gel electrophoresis (SDS-PAGE) and native enzyme was found to be 111,000 Da by gel filtration column chromatography. The enzyme had an optimal pH at 7.0 and stable pH at 8.0 in 1 M Tris-HCI buffer, and optimal temperature at 45 degreesC. K-M and V-MAX for NADP(+) and 6-PGA as substrates were also determined. The inhibitor effects of ATP, NADPH and NADH were also examined, and K, values and the types of inhibition were determined by means of a Lineweaver-Burk graph obtained for them.
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    Catechol oxidase activity in honey from eastern and south-eastern Anatolia
    (Int Bee Research Assoc, 2003) Yilmaz, H; Sakiroglu, H; Küfrevioglu, ÖI
    [Abstract Not Available]
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    Content of some trace metals in honey from south-eastern Anatolia
    (Elsevier Sci Ltd, 1999) Yilmaz, H; Yavuz, Ö
    Contents of Na, K, Ca, Mg, Cu, Fe, Mn, Zn and Co in honey (30 samples) from different parts of south-eastern Anatolia (Turkey) were determined by atomic absorption spectrometer AAS. The mean values for Na, K, Ca, Mg, Cu, Fe, Mn, Zn and Co were 118, 296, 51, 33, 1.8, 6.6, 1.0, 2.7 and 1.0 mg/kg, respectively. Also determined in the honey samples were invert sugar, sucrose, hydroxymethyifurfural, diastase activity, free acid, lactone, pH, ash, proline and moisture. In south-eastern Anatolia the honeys were found to have low ash contents, and some high mineral contents. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.
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    Effects of some drugs on rat erythrocyte 6-phosphogluconate dehydrogenase
    (Polish Acad Sciences Inst Pharmacology, 2002) Çiftçi, M; Beydemir, S; Yilmaz, H; Bakan, E
    The in vitro and in vivo effects of some drugs on rat erythrocytes 6-phosphogluconate dehydrogenase were investigated in this study. Rat erythrocyte 6-phosphogluconate dehydrogenase was partially purified with ammonium sulfate precipitation. The enzyme activity was determined by Beutler's method. Some drugs such as ampicillin, amikacin sulfate, and netilmicin sulfate inhibited the enzyme activity in in vitro conditions, while metamizole activated it. The I-50 values of the inhibiting drugs were 66.2, 5.836, and 0.963 mM, respectively. For the drugs having low I-50 values (drug concentrations which produce 50% inhibition) (amikacin sulfate and netilmicin sulfate), in vivo studies were performed in rats (Sprague-Dawley). Amikacin sulfate at 64 mg/kg inhibited the enzyme activity significantly (p < 0.05) 2 h after dosing. Netilmicin sulfate at 6.4 mg/kg also inhibited the enzyme significantly (p < 0.05) 4 h after dosing. Amikacin sulfate and netilmicin sulfate inhibited rat erythrocyte 6-phospogluconate dehydrogenase both in vivo and in vitro. The enzyme was inhibited in vitro by ampicillin and activated in vitro by metamizole.
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    Polyphenol oxidase from Mazruma grape (Vitis vinifera L.)
    (Ist Chimica Agraria, 2003) Yilmaz, H; Sakiroglu, H; Küfrevioglu, I
    Polyphenol oxidase of Mazruma grape (Vitis vinifera L. Mazruma) which is one of the most widely grown grape species in the south-eastern Anatolia region of Turkey was extracted and partially purified through ammonium sulphate precipitation and dialysis. The sample was used for characterization of the polyphenol oxidase. The enzyme showed affinity towards dihydroxy phenolic substrates but no activity towards monohydroxy phenols. The best substrate of the PPO was found to be 4-methylcatechol (highest V-max value). Optimum pH and temperature were found to be pH 6.5 and 20 degreesC, and K-M and V-max values were 6.8 mM and 2560 EU/mLmin with 4-methylcatechol, respectively. Inhibition studies indicated that L cysteine, sodium cyanide, ascorbic acid and sodium diethyl dithiocarbamate were the most effective, being able to completely inhibit enzyme activity at 5.0 mM concentration. Heat inactivation studies showed that temperature > 40 degreesC resulted in loss of enzyme activity, The enzyme was inactivited 77%, 86% and 94% after heating for 60 minute at temperatures of 50 degreesC, 60 degreesC and 70 degreesC respectively, and was competely inactivited at 80 degreesC after 10 min.
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    Purification and properties of glucose 6-phosphate dehydrogenase from turkey erythrocytes
    (Natl Inst Science Communication-Niscair, 2003) Yilmaz, H; Çiftçi, M; Beydemir, S; Bakan, E; Küfrevioglu, ÖI
    Glucose 6-phosphate dehydrogenase (G6PD) was purified from turkey erythrocytes by ammonium sulphate precipitation and followed by ADP Sepharose affinity gel chromatography. The yield was 49.71% and specific activity of the enzyme was found to be 4.4.16 EU/mg protein. By gel filtration the molecular mass was found to be 75 kDa. The enzyme had an optimum pH at 9.0, and opt;mum temperature at 50degreesC. K-m and V-max for NADP(+) and glucose 6- phosphate (G6-P) as substrates were also determined and effects of inhibitors such as ATP, NADH and NADPH were examined.
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    Purification of glucose 6-phosphate dehydrogenase from Buffalo (Bubalus bubalis) erythrocytes and investigation of some kinetic properties
    (Academic Press Inc Elsevier Science, 2003) Çiftçi, M; Beydemir, S; Yilmaz, H; Altikat, S
    Glucose 6-phosphate dehydrogenase (G6PD) was purified from buffalo (Bubalus bubalis) erythrocytes and some characteristics of the enzyme were investigated. The purification procedure was composed of two steps: hemolysate preparation and 2',5'-ADP Sepharose 4B affinity gel chromatography. Thanks to the two consecutive procedures, the enzyme, having a specific activity of 69.7 EU/mg proteins, was purified 650-fold with a yield of 31%. Optimal pH, stable pH, optimal temperature, molecular weight, and K-m and V-max values for NADP(+) and glucose 6-phosphate (G6-P) substrates were also determined for the enzyme. In addition K-i values and the type of inhibition were determined by means of Lineweaver-Burk graphs obtained for such inhibitors as ATP, ADP, NADPH, and NADH. (C) 2003 Elsevier Science (USA). All rights reserved.
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    Purification of glucose 6-phosphate dehydrogenase from chicken erythrocytes. Investigation of some kinetic properties
    (Taylor & Francis Inc, 2002) Yilmaz, H; Ciftci, M; Beydemir, S; Bakan, E
    Glucose 6-phosphate dehydrogenase (G6PD) was purified from chicken erythrocytes, and some characteristics of the enzyme were investigated. The purification procedure was composed of three steps: hemolysate preparation, ammonium sulfate precipitation, and 2',5'-ADP Sepharose 4B affinity gel chromatography. Thanks to the three consecutive procedures, the enzyme, having the specific activity of 20.862 EU/mg proteins, was purified with a yield of 54.68% and 9,150-fold. Optimal pH, stable pH, optimal temperature, molecular weight, and K-M and V-max values for NADP(+) and glucose 6- phosphate (G6-P) were also determined for the enzyme. In addition, K-i values and the type of inhibition were determined by means of Line-Weaver-Burk graphs obtained for such inhibitors as ATP, ADP, NADH, and NADPH.
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    Purification of glucose 6-phosphate dehydrogenase from goose erythrocytes and kinetic properties
    (Tubitak Scientific & Technological Research Council Turkey, 2003) Beydemir, S; Yilmaz, H; Çiftçi, M; Bakan, E; Küfrevioglu, ÖI
    Glucose 6-phosphate dehydrogenase (G6PD) was purified from goose erythrocytes and some characteristics of the enzyme were investigated. The purification procedure was composed of 3 steps: hemolysate preparation, ammonium sulfate precipitation, and 2', 5'-ADP Sepharose 4B affinity gel chromatography. Thanks to the 3 consecutive procedures, the enzyme, having a specific activity of 36.2 EU/mg protein, was purified for a yield of 68.79% and 3892 folds; to ascertain enzyme purity, SDS-PAGE was performed. Optimal pH, stable pH, optimal temperature, molecular weight, and K-m and V-max values for NADP(+) and glucose 5-phosphate (G6-P) substrates were also determined for the enzyme. In addition, K-i values and inhibition type were determined by means of Lineweaver-Burk graphs obtained for such inhibitors as ATP, ADP and NADPH. These materials inhibited the enzyme in a noncompetitive manner.