Properties of an Ecto-5’-Nucleotidase of the Renal Brush Border
作者:
Michel Le Hir,
Stefan Angielski,
Ulrich C. Dubach,
期刊:
Kidney and Blood Pressure Research
(Karger Available online 1985)
卷期:
Volume 8,
issue 6
页码: 321-327
ISSN:1420-4096
年代: 1985
DOI:10.1159/000173064
出版商: S. Karger AG
关键词: 5’-Nucleotidase;Ectoenzymes;Brush border;Kidney;Renal hemodynamics;Adenosine
数据来源: Karger
摘要:
A decrease of glomerular filtration rate can be observed during accelerated catabolism of ATP in kidney. It has been proposed that this effect is due to the increase in the renal production of adenosine from ATP. The last reaction in the pathway concerned is the conversion of 5’-AMP to adenosine. We found that brush border membranes purified from homogenates of the rat renal cortex carry out this reaction. The enzyme involved in the hydrolysis has the characteristic properties of ecto-5’-nucleotidases: It is inhibited by ATP, ADP, and by α, β-methyleneadenosine-5’-diphosphate, and it is not stimulated by magnesium. All catalytic sites are accessible from the outside of the vesicles. The Km of the enzyme for 5’-AMP is 5.77 µM. The enrichment of the 5’-AMP-hydrolyzing activity in the brush border fraction as compared to the homogenate is 9.2 ± 1.5 times. Histochemical staining of kidney sections reveals hydrolysis of 5’-AMP only at the brush border of the proximal tubule. We conclude that the brush border of the proximal tubule of the rat kidney possesses an ecto-5’-nucleotidase which has the same properties as the ecto-5’-nucleotidas
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