Ca4 Æ calmodulin (Ca4 Æ CaM) inhibits the glycolytic enzyme phosphofructokinase, by preventing formation of its active tetramer. Fluorescence titrations show that the affinity of complex formation of Ca4 ÆCaM with the key 21-residue target peptide increases 1000-fold from pH 9.0 to 4.8, suggesting the involvement of histidine and carboxylic acid residues. 1H NMR pH titration indicates a marked increase in pKa of the peptide histidine on complex formation and HSQC spectra show related pH-dependent changes in the conformation of the complex. This unusually strong sensitivity of a CaM–target complex to pH suggests a potential functional role for Ca4 ÆCaM in regulation of the glycolytic pathway.
Interaction of calmodulin with the phosphofructokinase target sequence
GUERRINI, Remo;SALVADORI, Severo;
2004
Abstract
Ca4 Æ calmodulin (Ca4 Æ CaM) inhibits the glycolytic enzyme phosphofructokinase, by preventing formation of its active tetramer. Fluorescence titrations show that the affinity of complex formation of Ca4 ÆCaM with the key 21-residue target peptide increases 1000-fold from pH 9.0 to 4.8, suggesting the involvement of histidine and carboxylic acid residues. 1H NMR pH titration indicates a marked increase in pKa of the peptide histidine on complex formation and HSQC spectra show related pH-dependent changes in the conformation of the complex. This unusually strong sensitivity of a CaM–target complex to pH suggests a potential functional role for Ca4 ÆCaM in regulation of the glycolytic pathway.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
