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Zinc ions bind to and inhibit activated protein C

Zhu, Tianqing and Ubhayasekera, Wimal and Nickolaus, Noëlle and Sun, Wei and Tingsborg, Susanne and Mowbray, Sherry L. and Schedin-Weiss, Sophia (2010). Zinc ions bind to and inhibit activated protein C. Thrombosis and haemostasis. 104:3, 544-553
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Official URL: http://dx.doi.org/10.1160/TH09-12-0862

Abstract

Zn2+ ions were found to efficiently inhibit activated protein C (APC), suggesting a potential regulatory function for such inhibition. APC activity assays employing a chromogenic peptide substrate demonstrated that the inhibition was reversible and the apparent K I was 13 +/- 2 muM. k cat was seven fold decreased whereas K M was unaffected in the presence of 10 muM Zn2+. The inhibitory effect of Zn2+ on APC activity was also observed when factor Va was used as a substrate in an assay coupled to a prothrombinase assay. The interaction of Zn2+ with APC was accompanied by a reversible ~40% decrease in tryptophan fluorescence, consistent with the ion inducing a conformational change in the protein. The apparent K D was 7.4 +/- 1.5 muM and thus correlated well with the apparent K I. In the presence of physiological Ca2+ concentration the K I and K D values were three to four fold enhanced, presumably due to the Ca2+-induced conformational change affecting the conformation of the Zn2+-binding site. The inhibition mechanism was non-competitive both in the absence and presence of Ca2+. Comparisons of sequences and structures suggested several possible sites for zinc binding. The magnitude of the apparent KI in relation to the blood and platelet concentrations of Zn2+ supports a physiological role for this ion in the regulation of anticoagulant activity of APC. These findings broaden the understanding of this versatile serine protease and enable the future development of potentially more efficient anticoagulant APC variants for treatments of thrombotic diseases.

Authors/Creators:Zhu, Tianqing and Ubhayasekera, Wimal and Nickolaus, Noëlle and Sun, Wei and Tingsborg, Susanne and Mowbray, Sherry L. and Schedin-Weiss, Sophia
Title:Zinc ions bind to and inhibit activated protein C
Series/Journal:Thrombosis and haemostasis (0340-6245)
Year of publishing :2010
Volume:104
Number:3
Page range:544-553
Publisher:Schattauer
ISSN:0340-6245
Language:English
Additional Information:This article is not an exact copy of the original published article in Thrombosis and haemostasis. The definitive publisher-authenticated version of "Zinc ions bind to and inhibit activated protein C" is available online at: http://www.schattauer.de/de/magazine/uebersicht/zeitschriften-a-z/thrombosis-and-haemostasis.html
Publication Type:Journal article
Refereed:Yes
Article category:Scientific peer reviewed
Version:Accepted version
Full Text Status:Public
Subjects:Obsolete subject words > NATURAL SCIENCES > Biology > Cell and molecular biology > Molecular biology
Keywords:activated protein C, serine protease, zinc, blood coagulation, enzyme inhibition
URN:NBN:urn:nbn:se:slu:epsilon-8-707
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-8-707
Additional ID:
Type of IDID
DOI10.1160/TH09-12-0862
ID Code:5218
Department:(NL, NJ) > Dept. of Molecular Biology (until 131231)
Deposited By: Sherry Mowbray
Deposited On:10 Sep 2010 00:00
Metadata Last Modified:02 Dec 2014 10:38

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