Background: Adenosine deaminase (ADA) and 5'-nucleotidase (5'-NT) play a crucial role in adenosine metabolism in healthy individuals. Adenosine is an inflammatory mediator of asthma. Changes in adenosine metab...Background: Adenosine deaminase (ADA) and 5'-nucleotidase (5'-NT) play a crucial role in adenosine metabolism in healthy individuals. Adenosine is an inflammatory mediator of asthma. Changes in adenosine metabolism and role of ADA and 5'-NT in regulating adenosine level in asthmatics and correlation of these changes with severity of asthma are not clearly understood. Methods: In this study, we screened 5217 patients, of which 2416 were diagnosed with asthma. Further, of 2416 asthmatics, only 45 patients who strictly fulfilled the selection criteria were enrolled in the study. The patients were classified into mild, moderate and severe persistent groups;each group consisted of fifteen patients. Fifteen healthy subjects served as controls. Adenosine levels and activities of 5'-NT, total ADA, ADA1 and ADA2 in serum, lymphocytes and erythrocytes were determined. The data were analysed statistically and p vice versa.展开更多
Cytosine Deaminase (CD) from Aspergillus parasiticus was purified and characterized. Time course for maximal CD production (50 μmol/min/mg) was at 72 hrs. The enzyme was purified 387.73 folds with an overall yield of...Cytosine Deaminase (CD) from Aspergillus parasiticus was purified and characterized. Time course for maximal CD production (50 μmol/min/mg) was at 72 hrs. The enzyme was purified 387.73 folds with an overall yield of 13%. The CD had pH optimum of 7.2, a temperature optimum of 40℃ - 45℃, activation of energy (Ea) of 8.4 KJ/mol and a t1/2 of 1.10 hr. A. parasiticus CD stoichiometrically deaminated Cyto-sine and 5-fluorocytosine (5-FC) with the KM values of 0.19mM and 0.30 mM respectively. Studies on the effect of pH on KM and Vmax gave pKa1 of 5.8 and pKa2 of 6.3 with enthalpy of ionization of 43.01 KJ/mole suggesting histidine in the active site. The enzyme was strongly inhibited by Ca2+, Co2+, Zn2+ and Hg2+ and completely inhibited by Cu2+ and Fe2+ at 50 mM. Therefore, A. parasiticus CD can be compared with CDs from other sources that are used in suicide gene therapy.展开更多
文摘Background: Adenosine deaminase (ADA) and 5'-nucleotidase (5'-NT) play a crucial role in adenosine metabolism in healthy individuals. Adenosine is an inflammatory mediator of asthma. Changes in adenosine metabolism and role of ADA and 5'-NT in regulating adenosine level in asthmatics and correlation of these changes with severity of asthma are not clearly understood. Methods: In this study, we screened 5217 patients, of which 2416 were diagnosed with asthma. Further, of 2416 asthmatics, only 45 patients who strictly fulfilled the selection criteria were enrolled in the study. The patients were classified into mild, moderate and severe persistent groups;each group consisted of fifteen patients. Fifteen healthy subjects served as controls. Adenosine levels and activities of 5'-NT, total ADA, ADA1 and ADA2 in serum, lymphocytes and erythrocytes were determined. The data were analysed statistically and p vice versa.
文摘Cytosine Deaminase (CD) from Aspergillus parasiticus was purified and characterized. Time course for maximal CD production (50 μmol/min/mg) was at 72 hrs. The enzyme was purified 387.73 folds with an overall yield of 13%. The CD had pH optimum of 7.2, a temperature optimum of 40℃ - 45℃, activation of energy (Ea) of 8.4 KJ/mol and a t1/2 of 1.10 hr. A. parasiticus CD stoichiometrically deaminated Cyto-sine and 5-fluorocytosine (5-FC) with the KM values of 0.19mM and 0.30 mM respectively. Studies on the effect of pH on KM and Vmax gave pKa1 of 5.8 and pKa2 of 6.3 with enthalpy of ionization of 43.01 KJ/mole suggesting histidine in the active site. The enzyme was strongly inhibited by Ca2+, Co2+, Zn2+ and Hg2+ and completely inhibited by Cu2+ and Fe2+ at 50 mM. Therefore, A. parasiticus CD can be compared with CDs from other sources that are used in suicide gene therapy.
