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)|
|Link:||<Go to ISI>://000183673100039|
|Appears in Collections:||Άρθρα σε επιστημονικά περιοδικά ( Ανοικτά)|
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