| Autor: |
Yayoi Koide, Jan Sääf, Norio Koide, Lennart Wetterberg, Svante B. Ross |
| Rok vydání: |
1981 |
| Předmět: |
|
| Zdroj: |
Biochemical Pharmacology. 30:2893-2900 |
| ISSN: |
0006-2952 |
| DOI: |
10.1016/0006-2952(81)90249-5 |
| Popis: |
The kinetic properties of human platelet monoamine oxidase (MAO) were examined in 20 apparently healthy controls. The mean value (±S.D.) of the maximum velocity ( V ) was found to be 5.36 ± 1.97 pmoles of product formed/10° platelets/min and the Michaelis-Menten constants were for phenethylamine ( K PEA m ) 14.6 ± 8.20 μ M and for oxygen ( K m O 2 )254 ± 125 μ M, when assayed in 0.1 M phosphate buffer, pH 7.4. The relation between the value of the corresponding apparent constants was studied. Inhibition of the enzyme activity was seen at 20 μM of PEA and 180 μM of oxygen. The enzyme kinetics were also studied at different pH. Two p K values were found, p K 1 = 6.65 and p K 2 = 6.95. The influence of homogenization on the MAO activity was compared with the activity in the undisrupted platelet. At PEA concentrations below 10 μM higher MAO activities were found in the intact cell. A 15 per cent loss of activity was detected in platelet samples after storing at −20° for three and a half years. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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