Yaşar Demir

Bio: Yaşar Demir is an academic researcher from Atatürk University. The author has contributed to research in topics: Carbonic anhydrase & Enzyme. The author has an hindex of 7, co-authored 38 publications receiving 200 citations. Previous affiliations of Yaşar Demir include Bar-Ilan University & Muğla University.

Cysteine protease (Capparin) from capsules of caper (Capparis spinosa).

Abstract: Summary Proteases are enzymes that perform very important functions in organisms and are used for a variety of objectives in vitro. In recent years, proteases have been used for clinical, pharmaceutical (alimentary digestion, anti-inflammatory, etc.) and industrial applications (cheese production, meat tenderizing, leather tanning). In this research, a protease has been purified from capsules of caper (Capparis spinosa) and characterized. Caper plants have been used for food and medicine since ancient times. The plant grows abundantly in certain regions of Turkey. Ammonium sulphate fractionation and a CM Sephadex column were used for purification of the enzyme. The purification enzyme has an optimum pH=5.0 and its optimum temperature was 60 °C. The vmax and Km values determined by Lineweaver-Burk graphics were 1.38 mg/(L·min) and 0.88 mg/L, respectively. The purification degree and the molecular mass of the enzyme (46 kDa) were determined by SDS-PAGE and gel filtration chromatography. It was investigated whether the purified and characterized protease could cause milk to congeal or digest chicken and cow meat. The results show that protease can be used for industrial production.

Purification and characterization of an alkaline pectin lyase produced by a newly isolated Brevibacillus borstelensis (P35) and its applications in fruit juice and oil extraction

Abstract: An alkaline pectin lyase (PNL) (EC 4.2.2.10) secreted by Brevibacillus borstelensis P35 (GenBank Number: FJ417406) was purified using ammonium sulfate fractionation, anion exchange chromatography on DEAE-cellulose and gel filtration chromatography on Sephadex G-150. The pH and temperature optima of the enzyme were found to be 8.0 and 60 °C. The enzyme does not loose activity up to 60 °C if exposed for 1 h. The values of K m and V max of the enzyme were 0.625 mg/mL and 126.32 s−1, respectively. The molecular weight was found to be 36 ± 01 kDa. The presence of 10 mM concentration of Ca2+, Cu2+, Mn2+, Mg2+, Zn2+, Hg2+, Fe2+ and EDTA, l-cystein, ascorbic acid significantly enhanced the PNL of the purified enzyme. In the course of the laboratory trials, it was demonstrated that PNL from B. borstelensis (P35) could be successfully applied to the production and clarification of fruit juice and oil extraction.

Identification of protease from Euphorbia amygdaloides latex and its use in cheese production.

Abstract: In this research, protease enzyme was purified and characterized from milk of Euphorbia amygdaloides. (NH4)2SO4 fractionation and CM-cellulose ion exchange chromatography methods were used for purification of the enzyme. The optimum pH value was determined to be 5, and the optimum temperature was determined to be 60 degrees C. The V(max) and K(M) values at optimum pH and 25 degrees C were calculated by means of Linewearver-Burk graphs as 0.27 mg/L min(-1) and 16 mM, respectively. The purification degree was controlled by using SDS-PAGE and molecular weight was found to be 26 kD. The molecular weight of the enzyme was determined as 54 kD by gel filtration chromatography. These results show that the enzyme has two subunits. In the study, it was also researched whether purified and characterized protease can be collapsed to milk. It was determined that protease enzyme can collapse milk and it can be used to produce cheese.

Purification and characterisation of a plant peroxidase from rocket (Eruca vesicaria sbsp. Sativa) (Mill.) (syn. E. sativa) and effects of some chemicals on peroxidase activity

Abstract: Rocket (Eruca vesicaria sbsp. Sativa) (Mill.) (syn. E. sativa) was grown and used widely in Turkey as a garnish in salads. A peroxidase (POD) from leaves of rocket (Eruca vesicaria sbsp. Sativa) was purified using sequential (NH4)2SO4 precipitation, CM-Sephadex and Sephacryl S-200 chromatographies. A peroxidase (POD) was purified 220.3-fold from the Rocket (E. vesicaria sbsp. Sativa) with an overall yield of 80.79%. The purified enzyme has an optimum pH, 6.0 and its optimum temperature was 40°C. The Vmax and KM values were determined by Lineweaver-Burk graphics using different substrates. The purification degree and the molecular mass of the enzyme (34 kDa) were determined by SDS-PAGE and gel filtration chromatography. POD enzyme activity was strongly inhibited by Ca2+, Mn2+, Hg22+, Zn2+ and Fe2+ as metal ions and SDS, EDTA, ascorbic acid, dithioeritritol as chemicals. But, Ni2+, Co2+, Cu2+ slightly activated the enzyme. They inhibited in the different range of peroxidase activity. Changes of POD enzyme’s kinetic parameters were most important during chemicals and metal ions metabolism, because they were risk for environmental pollution. Key words: Rocket (Eruca vesicaria sbsp. Sativa), peroxidase (POD), purification, metal ions.

Purification and Characterization of Carbonic Anhydrase from Human Erythrocyte Plasma Membrane

Abstract: Carbonic anhydrase is the basic enzyme in inhalation function. Untill now no research had been done to determine whether CA is in the human erythrocyte plasma membrane or not. Carbonic anhydrase (CA) was purified from human erythrocyte plasma membrane and described in this study. For this purpose, the blood samples taken from young human test subjects were hemolyzed, then the membrane fraction was separated, and this fraction was repeatedly washed. The enzyme (CA) was removed from the membrane with buffered TritonX-100 (1%), which was purified with a factor of 119.19 by affinity chromatography. The CA obtained from the erythrocyte membrane has esterase activity as well as hydratase activity. The Vmax and KM of the enzyme for the substrate (p-nitrophenyl acetate) are 1.517*10-1 µM/L*min. and 1.78 mM, respectively. The purification degree of the enzyme was controlled by SDS-PAGE (3-10%), which showed one distinct band. It was determined that the enzyme was active within the pH range of 4-10, and that the optimal pH was 7.5. The temperature at which it showed activity was 5-70oC, and optimal temperature was 35oC. The molecular weight of CA was found to be ~ 36,600 by gel filtration. On the other hand, sulphanilamide, KSCN and NaN3 inhibited the enzyme. Finally, CA was shown to be present in human erythrocyte plasma membrane and this enzyme is optimized.

Metal-Assisted Cycloaddition Reactions in Organotransition Metal Chemistry

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A Comprehensive Review on Function and Application of PlantPeroxidases

Abstract: Peroxidases, one of the key antioxidant enzymes, are widely distributed in nature and catalyze oxidation of various electron donor substrates concomitant with the decomposition of H2O2. The non-animal plant peroxidases (class III peroxidase) are involved in various essential physiological processes of plant growth and development throughout their life cycle. In view of the capability of peroxidases to catalyze the redox reaction for a wide range of substrates, they are considered as one of the important enzyme from the point of view of their various medicinal, biochemical, immunological, biotechnological and industrial applications. They have been successfully used for biopulping and biobleaching in the paper and textile industries. Peroxidases have also been used in organic synthesis, bioremediation, as well as various analytical applications in diagnostic kits, ELISA. Peroxidase based biosensors find application in analytical systems for determination of hydrogen peroxide, glucose, alcohols, glutamate, and choline etc. Thus, in view of array of physiological functions as well as industrial applications, the peroxidases have conquered a dominant position in research groups and become one of the most extensively studied enzymes. In this direction, the present review embodies the classification, mechanism of action, major physiological functions as well as industrial applications of plant peroxidases.

A magnificent enzyme superfamily: carbonic anhydrases, their purification and characterization

Abstract: In this paper, we reviewed the purification and characterization methods of the α-carbonic anhydrase (CA, EC 4.2.1.1) class. Six genetic families (α-, β-, γ-, δ-, ζ- and η-CAs) all know to date, all encoding such enzymes in organisms widely distributed over the phylogenetic tree. Starting from the manuscripts published in the 1930s on the isolation and purification of α-CAs from blood and other tissues, and ending with the recent discovery of the last genetic family in protozoa, the η-CAs, considered for long time an α-CA, we present historically the numerous and different procedures which were employed for obtaining these catalysts in pure form. α-CAs possess important application in medicine (as many human α-CA isoforms are drug targets) as well as biotechnological processes, in which the enzymes are ultimately used for CO2 capture in order to mitigate the global warming effects due to greenhouse gases. Recently, it was discovered an involvement of CAs in cancerogenesis as well as infection caus...