yaşar şahin | Cukurova University (original) (raw)

Papers by yaşar şahin

Research paper thumbnail of Erythrocyte membrane glycation and NA +–K + levels in NIDDM

Journal of Diabetes and Its Complications, 2002

Although there are many investigations on protein glycation in diabetic patients, many detailed s... more Although there are many investigations on protein glycation in diabetic patients, many detailed studies are needed on this subject. In this study, the correlation between red cell membrane and serum protein glycation was investigated in NIDDM. The relation of membrane glycation to intracellular Na + and K + levels was also considered. Forty patients with NIDDM and 22 healthy subjects were included in the study. The membrane proteins were isolated, and total protein (TP m ) and fructosamine (FA m ) levels were determined. Serum glucose, fructosamine (FA s ) and total protein (TP s ) levels were also measured. HbA 1C , red blood cell (RBC) and reticulocyte (RET) counts in whole blood were made in all samples. NA + and K + levels of both serum and RBC were determined. The patient group had lower levels of K + RBC ( P < .001) and Na + s ( P < .05) and RBC count ( P < .05), and higher levels of FA m ( P < .001), Na + RBC ( P < .01), K + s ( P < .01), glucose ( P < .001) and HbA 1C ( P < .001) than those of controls. The ratios of FA s /TP s ( P < .001) and FA m /TP m ( P < .001) were higher in patients than in control. As a result, HbA 1C levels and the ratio of FA m /TP m were high in NIDDM patients ( P < .001) and these patients have slight negative correlations in FA m /TP m and FA s /TP s ( P < .05). On the other hand, that there is no correlation between RBC membrane protein glycation and RBC Na + and K + levels may be caused by the fact that the membrane protein glycation is lower than that of other soluble proteins and that the membrane proteins are functional with respect to Na + -K + transport. D

Research paper thumbnail of Partial characterization of polyphenoloxidase from a hybridized wheat ( Triticum aestivum L

European Food Research and Technology, 2010

Polyphenol oxidase was extracted and partially purified from wheat leaves by a procedure that inc... more Polyphenol oxidase was extracted and partially purified from wheat leaves by a procedure that included ammonium sulfate fractionation followed by dialysis and gel filtration chromatography. These procedures led to 35.21-fold purification with 17.65% recovery. Optimum pH, temperature, and ionic strength were determined with six substrates. Some kinetic properties of the enzyme such as V max,K M, and k cat were calculated for the substrates. The k cat/K M values of the PPO for catechol, catechin, pyrogallol, l-dopa, dopamine, and 4-methyl catechol were 31408, 31167, 28404, 15378, 4865, and 4967 mM/min, respectively. The best substrate of wheat PPO was found to be catechol. The native molecular weight of the PPO was estimated to be 243 kDa based on its mobility in gel filtration column. The inhibitory effects of glutathione, sodium azide, ascorbic acid, oxalic acid, l-cysteine, and thiourea on the reaction catalyzed by the enzyme were tested, and I 50 values were estimated to be 8.0 mM, 10.12 mM, 11.18 mM, 77.33 mM, 183 mM, and 413 mM, and K i constants were also calculated as 0.416 ± 0.244 mM, 0.317 ± 0.208 mM, 0.820 ± 0.111 mM, 13.80 ± 1.179 mM, 14.10 ± 5.069 mM, and 130 ± 62.45 mM, respectively, by means of Lineweaver–Burk graphs. The most effective inhibitor was glutathione. Glutathione, sodium azide, oxalic acid, and thiourea were competitive inhibitors, whereas ascorbic acid and l-cysteine were also noncompetitive inhibitors.

Research paper thumbnail of Erythrocyte membrane glycation and NA +–K + levels in NIDDM

Journal of Diabetes and Its Complications, 2002

Although there are many investigations on protein glycation in diabetic patients, many detailed s... more Although there are many investigations on protein glycation in diabetic patients, many detailed studies are needed on this subject. In this study, the correlation between red cell membrane and serum protein glycation was investigated in NIDDM. The relation of membrane glycation to intracellular Na + and K + levels was also considered. Forty patients with NIDDM and 22 healthy subjects were included in the study. The membrane proteins were isolated, and total protein (TP m ) and fructosamine (FA m ) levels were determined. Serum glucose, fructosamine (FA s ) and total protein (TP s ) levels were also measured. HbA 1C , red blood cell (RBC) and reticulocyte (RET) counts in whole blood were made in all samples. NA + and K + levels of both serum and RBC were determined. The patient group had lower levels of K + RBC ( P < .001) and Na + s ( P < .05) and RBC count ( P < .05), and higher levels of FA m ( P < .001), Na + RBC ( P < .01), K + s ( P < .01), glucose ( P < .001) and HbA 1C ( P < .001) than those of controls. The ratios of FA s /TP s ( P < .001) and FA m /TP m ( P < .001) were higher in patients than in control. As a result, HbA 1C levels and the ratio of FA m /TP m were high in NIDDM patients ( P < .001) and these patients have slight negative correlations in FA m /TP m and FA s /TP s ( P < .05). On the other hand, that there is no correlation between RBC membrane protein glycation and RBC Na + and K + levels may be caused by the fact that the membrane protein glycation is lower than that of other soluble proteins and that the membrane proteins are functional with respect to Na + -K + transport. D

Research paper thumbnail of Partial characterization of polyphenoloxidase from a hybridized wheat ( Triticum aestivum L

European Food Research and Technology, 2010

Polyphenol oxidase was extracted and partially purified from wheat leaves by a procedure that inc... more Polyphenol oxidase was extracted and partially purified from wheat leaves by a procedure that included ammonium sulfate fractionation followed by dialysis and gel filtration chromatography. These procedures led to 35.21-fold purification with 17.65% recovery. Optimum pH, temperature, and ionic strength were determined with six substrates. Some kinetic properties of the enzyme such as V max,K M, and k cat were calculated for the substrates. The k cat/K M values of the PPO for catechol, catechin, pyrogallol, l-dopa, dopamine, and 4-methyl catechol were 31408, 31167, 28404, 15378, 4865, and 4967 mM/min, respectively. The best substrate of wheat PPO was found to be catechol. The native molecular weight of the PPO was estimated to be 243 kDa based on its mobility in gel filtration column. The inhibitory effects of glutathione, sodium azide, ascorbic acid, oxalic acid, l-cysteine, and thiourea on the reaction catalyzed by the enzyme were tested, and I 50 values were estimated to be 8.0 mM, 10.12 mM, 11.18 mM, 77.33 mM, 183 mM, and 413 mM, and K i constants were also calculated as 0.416 ± 0.244 mM, 0.317 ± 0.208 mM, 0.820 ± 0.111 mM, 13.80 ± 1.179 mM, 14.10 ± 5.069 mM, and 130 ± 62.45 mM, respectively, by means of Lineweaver–Burk graphs. The most effective inhibitor was glutathione. Glutathione, sodium azide, oxalic acid, and thiourea were competitive inhibitors, whereas ascorbic acid and l-cysteine were also noncompetitive inhibitors.