In:
Fundamental & Clinical Pharmacology, Wiley, Vol. 20, No. 6 ( 2006-12), p. 613-619
Abstract:
Membranes of HEK293 cells that were transfected with human aminopeptidase N (AP‐N, CD13, EC 3.4.11.2) and purified soluble porcine kidney AP‐N were used to study inhibition of its enzyme activity by divalent cation chelators. Whereas pre‐incubation for 10 min with ethylenediaminetetraacetic acid (EDTA), did not or only weakly affected the enzyme activity, the bidentate chelator 1,10‐phenanthroline produced a complete and concentration‐dependent inhibition of AP‐N. The corresponding curves had Hill slopes of 2.50 ± 0.23 and 2.73 ± 0.01 for soluble and recombinant AP‐N respectively. EDTA increased the potency of 1,10‐phenanthroline till a limit, at which Hill slopes became close to unity. In the absence of EDTA, the inhibition by 1,10‐phenanthroline was only weakly affected by the substrate concentration. On the other hand, competition between 1,10‐phenanthroline and the substrate took place in the presence of EDTA. Similar findings were reported for the related metallopeptidase cystinyl aminopeptidase and point towards a model in which 1,10‐phenanthroline inhibit enzyme activity by decreasing the free Zn 2+ concentration. Moreover, EDTA is capable of removing a modulatory ion from an allosteric site at the enzyme, facilitating the direct interaction between 1,10‐phenanthroline and the catalytic Zn 2+ . Compatible with this model, Ca 2+ may bind to this allosteric site resulting in the potentiation of Zn 2+ ‐mediated re‐activation of the enzyme activity in the presence of EDTA and 1,10‐phenanthroline.
Type of Medium:
Online Resource
ISSN:
0767-3981
,
1472-8206
DOI:
10.1111/fcp.2006.20.issue-6
DOI:
10.1111/j.1472-8206.2006.00444.x
Language:
English
Publisher:
Wiley
Publication Date:
2006
detail.hit.zdb_id:
2006242-4
SSG:
15,3
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