Ternary systems of Zn2+ and Cd2+, 2-(alpha-hydroxyethyl)thiamin pyrophosphate (HETPP) and the pentapeptide Asp-Asp-Asn-Lys-Ile. Implications for the mechanism of thiamin enzymes (Journal article)

Malandrinos, G./ Louloudi, M./ Hadjiliadis, N.

To obtain structural information on the active-site of thiamin-dependent enzymes in solution, the interaction of Zn2+ and Cd2+ ions with the pentapeptide Asp-Asp-Asn-Lys-Ile surrounding the thiamin pyrophosphate moiety in the transketolase enzyme, and the tertiary Zn2+/or Cd2+-pentapeptide-HETPP systems have been studied by NMR spectroscopy in aqueous solutions at physiological pH. The HETPP, 2-(alpha-hydroxyethyl)thiamin pyrophosphate, represents an active intermediate of thiamin catalytic cycle formed after the addition of pyruvate substrate on thiamin molecule. The present data show the existence of the tertiary metal-[pentapeptide]-[HETPP] complexes at physiological pH, where the metal coordination sphere is completed by both peptide backbone and HETPP molecule. The metal coordinated HETPP molecule adopts the so-called S conformation in solution. The importance of the present findings correlated with previous results is discussed and possible functional implications are suggested. (C) 2003 Elsevier Science B.V. All rights reserved.
Institution and School/Department of submitter: Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας
Keywords: thiamin complexes,metal complexes,thiamin catalysis,diphosphate-dependent enzymes,crystal-structure,pyruvate decarboxylase,angstrom resolution,metal-complexes,transketolase,model,cadmium(ii),catalysis,zinc(ii)
URI: http://olympias.lib.uoi.gr/jspui/handle/123456789/9563
ISSN: 0020-1693
Link: <Go to ISI>://000183673100039
Publisher: Elsevier
Appears in Collections:Άρθρα σε επιστημονικά περιοδικά ( Ανοικτά)

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