SPERANZA, Maria L.;
VALENTINI, Giovanna;
MALCOVATI, Massimo
Fructose‐1,6‐bisphosphate‐activated pyruvate kinase from Escherichia coli : Nature of bonds involved in the allosteric mechanism
: Nature of bonds involved in the allosteric mechanism
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Medientyp:
E-Artikel
Titel:
Fructose‐1,6‐bisphosphate‐activated pyruvate kinase from Escherichia coli : Nature of bonds involved in the allosteric mechanism
:
Nature of bonds involved in the allosteric mechanism
Beteiligte:
SPERANZA, Maria L.;
VALENTINI, Giovanna;
MALCOVATI, Massimo
Beschreibung:
<jats:p>The allosteric properties of the fructose‐1,6‐bis‐phosphate‐activated pyruvate kinase from <jats:italic>Escherichia coli</jats:italic> were examined in the presence of a number of fructose bisphosphate analogues, as well as of increased ionic strength (NaCl) and of the hydrogen‐bond‐breaking agent, formamide.</jats:p><jats:p>Fructose 2,6‐bisphosphate, ribulose 1,5‐bisphosphate and 5‐phosphorylribose 1‐pyrophosphate gave allosteric activation (additive to that of fructose 1,6‐bisphosphate).</jats:p><jats:p>Formamide always decreased <jats:italic>V</jats:italic><jats:sub>max</jats:sub>, but left unchanged the <jats:italic>K</jats:italic><jats:sub>m</jats:sub> for phosphoenopyruvate, while it decreased the concentration of fructose bisphosphate required to give half‐maximal activity (<jats:italic>K</jats:italic><jats:sub>0.5</jats:sub>).</jats:p><jats:p>NaCl increased the <jats:italic>K</jats:italic><jats:sub>0.5</jats:sub> for both phosphoenolpyruvate and fructose bisphosphate, leaving <jats:italic>V</jats:italic><jats:sub>max</jats:sub> unchanged.</jats:p><jats:p>These results are consistent with ionic binding of fructose bisphosphate through phosphates and with a critical role of hydrogen bonds in stabilizing both the inactive and the active enzyme conformers.</jats:p>