Abstract
In studying transketolase (TK) from Saccharomyces cerevisiae, the majority of researchers use as cofactors Mg2+ and thiamine diphosphate (ThDP) (by analogy with other ThDP-dependent enzymes), whereas the active site of native holoTK is known to contain only Ca2+. Experiments in which Mg2+ was substituted for Ca2+ demonstrated that the kinetic properties of TK varied with the bivalent cation cofactor. This led to the assumption that TK species obtained by reconstitution from apoTK and ThDP in the presence of Ca2+ or Mg2+, respectively, adopt different conformations [Selivanov, V.A., Kovina, M.V., Kochevova, N.V., Meshalkina, L.E., Kochetov, G.A., 2004. Kinetic study of the H103A mutant yeast transketolase. FEBS Letters 567, 270-274]. Analysis of far-UV circular dichroism (CD) spectra and of data, obtained using methods of thermal denaturing, differential scanning calorimetry (DSC) and tryptophan fluorescence spectroscopy, corroborated this assumption. Indeed, the ratios of secondary structure elements in the molecule of apoTK, recorded in the presence of Ca 2+ or Mg2+, respectively, turned out to be different. The two forms of the holoenzyme, obtained by reconstitution from apoTK and ThDP in the presence of Ca2+ or Mg2+, respectively, also differed in stability: the holoenzyme was more stable in the presence of Ca2+ than Mg2+.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 8-13 |
| Number of pages | 6 |
| Journal | Life Sciences |
| Volume | 78 |
| Issue number | 1 |
| DOIs | |
| State | Published - Nov 19 2005 |
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All Science Journal Classification (ASJC) codes
- Biochemistry, Genetics and Molecular Biology(all)
- Pharmacology, Toxicology and Pharmaceutics(all)
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Effects of transketolase cofactors on its conformation and stability. / Esakova, Olga A.; Meshalkina, Ludmilla E.; Kochetov, German A.
In: Life Sciences, Vol. 78, No. 1, 19.11.2005, p. 8-13.Research output: Contribution to journal › Article
TY - JOUR
T1 - Effects of transketolase cofactors on its conformation and stability
AU - Esakova, Olga A.
AU - Meshalkina, Ludmilla E.
AU - Kochetov, German A.
PY - 2005/11/19
Y1 - 2005/11/19
N2 - In studying transketolase (TK) from Saccharomyces cerevisiae, the majority of researchers use as cofactors Mg2+ and thiamine diphosphate (ThDP) (by analogy with other ThDP-dependent enzymes), whereas the active site of native holoTK is known to contain only Ca2+. Experiments in which Mg2+ was substituted for Ca2+ demonstrated that the kinetic properties of TK varied with the bivalent cation cofactor. This led to the assumption that TK species obtained by reconstitution from apoTK and ThDP in the presence of Ca2+ or Mg2+, respectively, adopt different conformations [Selivanov, V.A., Kovina, M.V., Kochevova, N.V., Meshalkina, L.E., Kochetov, G.A., 2004. Kinetic study of the H103A mutant yeast transketolase. FEBS Letters 567, 270-274]. Analysis of far-UV circular dichroism (CD) spectra and of data, obtained using methods of thermal denaturing, differential scanning calorimetry (DSC) and tryptophan fluorescence spectroscopy, corroborated this assumption. Indeed, the ratios of secondary structure elements in the molecule of apoTK, recorded in the presence of Ca 2+ or Mg2+, respectively, turned out to be different. The two forms of the holoenzyme, obtained by reconstitution from apoTK and ThDP in the presence of Ca2+ or Mg2+, respectively, also differed in stability: the holoenzyme was more stable in the presence of Ca2+ than Mg2+.
AB - In studying transketolase (TK) from Saccharomyces cerevisiae, the majority of researchers use as cofactors Mg2+ and thiamine diphosphate (ThDP) (by analogy with other ThDP-dependent enzymes), whereas the active site of native holoTK is known to contain only Ca2+. Experiments in which Mg2+ was substituted for Ca2+ demonstrated that the kinetic properties of TK varied with the bivalent cation cofactor. This led to the assumption that TK species obtained by reconstitution from apoTK and ThDP in the presence of Ca2+ or Mg2+, respectively, adopt different conformations [Selivanov, V.A., Kovina, M.V., Kochevova, N.V., Meshalkina, L.E., Kochetov, G.A., 2004. Kinetic study of the H103A mutant yeast transketolase. FEBS Letters 567, 270-274]. Analysis of far-UV circular dichroism (CD) spectra and of data, obtained using methods of thermal denaturing, differential scanning calorimetry (DSC) and tryptophan fluorescence spectroscopy, corroborated this assumption. Indeed, the ratios of secondary structure elements in the molecule of apoTK, recorded in the presence of Ca 2+ or Mg2+, respectively, turned out to be different. The two forms of the holoenzyme, obtained by reconstitution from apoTK and ThDP in the presence of Ca2+ or Mg2+, respectively, also differed in stability: the holoenzyme was more stable in the presence of Ca2+ than Mg2+.
UR - http://www.scopus.com/inward/record.url?scp=23444455100&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=23444455100&partnerID=8YFLogxK
U2 - 10.1016/j.lfs.2004.12.055
DO - 10.1016/j.lfs.2004.12.055
M3 - Article
C2 - 16125202
AN - SCOPUS:23444455100
VL - 78
SP - 8
EP - 13
JO - Life Sciences
JF - Life Sciences
SN - 0024-3205
IS - 1
ER -