Examination of prostasomes, isolated from human seminal plasma, showed that there was very little remaining paranitrophenylphosphatase activity when assayed in the presence of 10 mmol/l of tartrate and 2 mmol/l of levamisole. Under these conditions it was possible to study the prostasome membrane-bound 5'-nucleotidase activity, which was unaffected by these two inhibitors. The activity was considered to be located at the external surface of the prostasome membrane and a 50-60% increase in activity was obtained by the addition of 0.05% Triton X-100. The prostasome membrane-linked 5'-nucleotidase readily hydrolysed 5'-AMP. Two other 5'-nucleoside monophosphates, 5'-IMP and 5'-GMP, were also hydrolysed, but more slowly; 2'- or 3'-AMP were practically not attacked. The prostasome membrane-linked 5'-nucleotidase obeyed Michaelis-Menten kinetics. Apparent Km for 5'-AMP was 11.2 +/- 2.1 mumol/l and Vmax 64.7 +/- 11.4 nmol/mg protein/min. These figures were somewhat changed in presence of 0.05% Triton X-100, the Km value being reduced by 30% and the Vmax value increased by 60%. Adenosine 5' (alpha, beta methylene) diphosphate (100 mumol/l), Ni2+ (10 mmol/l) and concanavalin A (20 micrograms/ml) were all potent inhibitors of the prostasome membrane-linked 5'-nucleotidase
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Titolo: | Characteristics of membrane-bound 5'-nucleotidase on human prostasomes |
Autori: | |
Data di pubblicazione: | 1993 |
Rivista: | |
Abstract: | Examination of prostasomes, isolated from human seminal plasma, showed that there was very little... remaining paranitrophenylphosphatase activity when assayed in the presence of 10 mmol/l of tartrate and 2 mmol/l of levamisole. Under these conditions it was possible to study the prostasome membrane-bound 5'-nucleotidase activity, which was unaffected by these two inhibitors. The activity was considered to be located at the external surface of the prostasome membrane and a 50-60% increase in activity was obtained by the addition of 0.05% Triton X-100. The prostasome membrane-linked 5'-nucleotidase readily hydrolysed 5'-AMP. Two other 5'-nucleoside monophosphates, 5'-IMP and 5'-GMP, were also hydrolysed, but more slowly; 2'- or 3'-AMP were practically not attacked. The prostasome membrane-linked 5'-nucleotidase obeyed Michaelis-Menten kinetics. Apparent Km for 5'-AMP was 11.2 +/- 2.1 mumol/l and Vmax 64.7 +/- 11.4 nmol/mg protein/min. These figures were somewhat changed in presence of 0.05% Triton X-100, the Km value being reduced by 30% and the Vmax value increased by 60%. Adenosine 5' (alpha, beta methylene) diphosphate (100 mumol/l), Ni2+ (10 mmol/l) and concanavalin A (20 micrograms/ml) were all potent inhibitors of the prostasome membrane-linked 5'-nucleotidase |
Handle: | http://hdl.handle.net/11391/922724 |
Appare nelle tipologie: | 1.1 Articolo in rivista |