HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 283, Issue 33, 22582-22590, August 15, 2008

This Article Full Text Full Text (PDF) Supplemental Data All Versions of this Article: 283/33/22582    most recent M802555200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Lockridge, O. Articles by Masson, P. Search for Related Content PubMed PubMed Citation Articles by Lockridge, O. Articles by Masson, P. Social Bookmarking                      What's this?

Pseudo-esterase Activity of Human Albumin

SLOW TURNOVER ON TYROSINE 411 AND STABLE ACETYLATION OF 82 RESIDUES INCLUDING 59 LYSINES^*

Oksana Lockridge, Weihua Xue, Andrea Gaydess, Hasmik Grigoryan, Shi-Jian Ding^¶, Lawrence M. Schopfer, Steven H. Hinrichs^¶, and Patrick Masson^||1

From the Eppley Institute, Environmental Health and Toxicology, and the ^¶Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska 68198 and the ^||Unité d'Enzymologie, Centre de Recherches d Service de Santé des Armées, BP87, 38702 La Tronche Cedex, France

Human albumin is thought to hydrolyze esters because multiple equivalents of product are formed for each equivalent of albumin. Esterase activity with p-nitrophenyl acetate has been attributed to turnover at tyrosine 411. However, p-nitrophenyl acetate creates multiple, stable, acetylated adducts, a property contrary to turnover. Our goal was to identify residues that become acetylated by p-nitrophenyl acetate and determine the relationship between stable adduct formation and turnover. Fatty acid-free human albumin was treated with 0.5 mM p-nitrophenyl acetate for 5 min to 2 weeks, or with 10 mM p-nitrophenyl acetate for 48 h to 2 weeks. Aliquots were digested with pepsin, trypsin, or GluC and analyzed by mass spectrometry to identify labeled residues. Only Tyr-411 was acetylated within the first 5 min of reaction with 0.5 mM p-nitrophenyl acetate. After 0.5–6 h there was partial acetylation of 16–17 residues including Asp-1, Lys-4, Lys-12, Tyr-411, Lys-413, and Lys-414. Treatment with 10 mM p-nitrophenyl acetate resulted in acetylation of 59 lysines, 10 serines, 8 threonines, 4 tyrosines, and Asp-1. When Tyr-411 was blocked with diisopropylfluorophosphate or chlorpyrifos oxon, albumin had normal esterase activity with β-naphthyl acetate as visualized on a nondenaturing gel. However, after 82 residues had been acetylated, esterase activity was almost completely inhibited. The half-life for deacetylation of Tyr-411 at pH 8.0, 22 °C was 61 ± 4 h. Acetylated lysines formed adducts that were even more stable. In conclusion, the pseudo-esterase activity of albumin is the result of irreversible acetylation of 82 residues and is not the result of turnover.

Received for publication, April 2, 2008 , and in revised form, June 2, 2008.

^* This work was supported, in whole or in part, by the National Institutes of Health NIH CounterACT U01 NS058056-02 (to O. L.) and NIH Eppley Cancer Center Grant P30CA36727. This work was also supported by U.S. Army Medical Research and Materiel Command W81XWH-07-2-0034 (to O. L.), W81XWH-06-1-0102 (to S. H. H.), and DGA Grant 03co010-05/PEA01 08 7 (to P. M.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The on-line version of this article (available at http://www.jbc.org) contains supplemental Figs. S1–S3 and Table S1.

¹ To whom correspondence should be addressed: Eppley Institute, University of Nebraska Medical Center, Omaha, NE 68198-6805. Tel.: 402-559-6032; Fax: 402-559-4651; E-mail: olockrid{at}unmc.edu.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				B. Li, L. M. Schopfer, H. Grigoryan, C. M. Thompson, S. H. Hinrichs, P. Masson, and O. Lockridge Tyrosines of Human and Mouse Transferrin Covalently Labeled by Organophosphorus Agents: A New Motif for Binding to Proteins that Have No Active Site Serine Toxicol. Sci., January 1, 2009; 107(1): 144 - 155. [Abstract] [Full Text] [PDF]