Biochemical study for diamine oxidase(DAO) was undertaken in human placentral tissues of early and term pregnancies. Distribution and activity of DAO were studied and also specificities and km values on .each substrates were measured. The results were as follows;
1. The activities of DAO were 33. 89 unit, g tissue in early placenta and 22.39 unit/g tissue in term placenta.
4
2. In early placenta, the distribution of DAO was 83% on cytosol fraction, 12%´ on mitochondrial fraction and 5% on nuclei,
3. In term placenta, the distribution was 85% on cytosol fraction, 9% on mitochondrial fraction and 5% on nuclei.
-4. In 1 g of early placental tissue, protein concentration within cytosol fraction was 9.220. 10 mg, activities of DAO on each substrate were 27.620. 83 unt/g on putrescine, 37.03+1.44 unit/g on cadaverine, 47.611.44 unit/g on histamine, 41. 310.75 unit/g on spermidine, and 52. 901. 44 unit/g on spermine.
.5. In term placenta, protein concentration within cytosol fraction was 6.540. 08 mg/g, the activities were 19.74+0.22 unit on putrescine, 18. 50+0. 38 unit on cadaverine, 14. 65-?-0. 22 unit on histamine; 16. 19-1-0.38 unit on spermidine and 28.520. 58unit on spermine.
6. Almost specific activities of DAO on each substrates were higher in early placental tissue than in term placental tissue, except for specific activity on putrescine.
7. Km values on each substrates were not different in early and term placental tissues. In early placenta, Km value was 0. 813 mM on putrescine, 1.587 mM on cadaverine, 1.408 mM on histamine, 1.282 mM on spermidine, and 0. 806 mM on spermine. In term placenta, Km value was 0. 806 m-NI on putrescine, 1. 613 mM on cadaverine, 1.333 mM on histamine, 1. 316 mM on spermidine, and 0.847 miM on spermine.
These results suggest that diamine oxidase and polyamine oxidase, the enzymes which catalyse, diamine and polyamine, exist in human placental tissues and higher concentration of these enzymes exist in early placental tissue. Also, different activities of these enzymes in both placental tissues presumably indicate that physiologic roles of amines metabolism in placental tissues are changed by the gestational age.
* 23 L- -T-
|