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

This Article Full Text Full Text (PDF) Alert me when this article is cited 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 Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Chen, J. Articles by Smith, D. L. Search for Related Content PubMed PubMed Citation Articles by Chen, J. Articles by Smith, D. L. Social Bookmarking                   What's this?

FOR THE RECORD

Amide hydrogen exchange shows that malate dehydrogenase is a folded monomer at pH 5

Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, USA

Reprint requests to: David L. Smith, Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588–0304, USA; e-mail: dsmith7{at}unl.edu 402-472-9402.

Although there is general agreement that native mitochondrial malate dehydrogenase (MDH) exists as a dimer at pH 7, its aggregation state at pH 5 is less certain. The present amide hydrogen exchange study was performed to determine whether MDH remains a dimer at pH 5. To detect pH-induced changes in solvent accessibility, MDH was exposed to D₂O at pH 5 or 7, then fragmented with pepsin into peptides that were analyzed by mass spectrometry. Even after adjustments for the effect of pH on the intrinsic rate of hydrogen exchange, large increases in deuterium levels were found at pH 5 only in peptic fragments derived from the subunit binding surface of MDH. In parallel experiments, elevated deuterium levels were also found in the same regions of MDH monomer trapped inside a mutant form of the chaperonin GroEL. This selective increase in hydrogen exchange rates, which was attributed to increased solvent accessibility of these regions, provides new evidence that MDH is a monomer at pH 5.

Keywords: Malate dehydrogenase; amide hydrogen exchange; mass spectrometry

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