Ca2+ metal ion adducts with cytosine, cytidine and cytidine 5′-monophosphate: a comprehensive study of calcium reactivity towards building units of nucleic acids

CrystEngComm ◽  
2014 ◽  
Vol 16 (35) ◽  
pp. 8286-8296 ◽  
Author(s):  
Nadia Marino ◽  
Donatella Armentano ◽  
Claudia Zanchini ◽  
Giovanni De Munno
Keyword(s):  
Nucleic Acids ◽  
Binding Sites ◽  
Calcium Ion ◽  
Metal Ion ◽  
Comprehensive Study

Six new Ca(ii) adducts with cytosine (cyt), cytidine (H2cyd) and cytidine 5′-monophosphate (CMP) are presented. H2cyd and CMP show unprecedented binding sites for the calcium ion.

scholarly journals Characterization of the two 5-aminolaevulinic acid binding sites, the A- and P-sites, of 5-aminolaevulinic acid dehydratase from Escherichia coli

1995 ◽  
Vol 305 (1) ◽  
pp. 151-158 ◽  
Author(s):  
P Spencer ◽  
P M Jordan
Keyword(s):  
Schiff Base ◽  
Binding Sites ◽  
Metal Ion ◽  
Substrate Binding ◽  
Aminolaevulinic Acid ◽  
Acid Dehydratase ◽  
Carboxylate Groups ◽  
Catalytic Metal ◽  
A Site ◽  
Aminolaevulinic Acid Dehydratase

Experiments are described in which the individual properties of the two 5-aminolaevulinic acid (ALA) binding sites, the A-site and the P-site, of 5-aminolaevulinic acid dehydratase (ALAD) have been investigated. The ALA binding affinity at the A-site is greatly enhanced (at least 10-fold) on the binding of the catalytic metal ion (bound at the alpha-site). The nature of the catalytic metal ion, Mg2+ or Zn2+, also gave major variations in the substrate Km, P-site affinity for ALA, the effect of potassium and phosphate ions and the pH-dependence of substrate binding. Modification of the P-site by reaction of the enzyme-substrate Schiff base with NaBH4 and analysis of the reduced adduct by electro-spray mass spectrometry indicated a maximum of 1 mol of substrate incorporated/mol of subunit, correlating with a linear loss of enzyme activity. The reduced Schiff-base adduct was used to investigate substrate binding at the A-site by using rate-of-dialysis analysis. The affinity for ALA at the A-site of Mg alpha Zn beta ALAD was found to determine the Km for the reaction and was pH-dependent, with its affinity increasing from 1 mM at pH 6 to 70 microM at pH 8.5. The affinity of ALA at the P-site of Zn alpha An beta ALAD is proposed to limit the Km at pH values above 7, since the measured Kd for ALA at the A-site in 45 microM Tris, pH 8, was well below the observed Km (600 microM) under the same conditions. The amino group of the ALA molecule bound at the P-site was identified as a critical binding component for the A-site, explaining why ALA binding to ALAD is ordered, with the P-site ALA binding first. Structural requirements for ALA binding at the A- and P-sites have been identified: the P-site requires the carbonyl and carboxylate groups, whereas the A-site requires the amino, carbonyl and carboxylate groups of the substrate.

The influence of metal-ion binding on the structure and surface composition of Sonic Hedgehog: a combined classical and hybrid QM/MM MD study

2016 ◽  
Vol 18 (32) ◽  
pp. 22254-22265 ◽  
Author(s):  
Manuel Hitzenberger ◽  
Thomas S. Hofer
Keyword(s):  
Metal Ions ◽  
Sonic Hedgehog ◽  
Binding Sites ◽  
Metal Ion ◽  
Surface Composition ◽  
Quantum Mechanical ◽  
Ion Binding ◽  
Metal Ion Binding ◽  
Structural Impact

The interaction of metal ions with Shh binding-sites and their structural impact are assessed via classical and quantum mechanical simulations.

scholarly journals SEPARATION OF Ca AND Fe METAL ION IN SOURCE WATER BY ADSORPTION COLUMN TECHNIC WITH LOCAL ZEOLITE AND ACTIVE CARBON

2016 ◽  
Vol 4 (1) ◽  
Author(s):  
Suyanta Suyanta ◽  
Hanafi Idham Kholid ◽  
Bambang S
Keyword(s):  
Active Carbon ◽  
Calcium Ion ◽  
Metal Ion ◽  
Calcium Concentration ◽  
Flow System ◽  
Iron Concentration ◽  
Source Water ◽  
Adsorption Time ◽  
Adsorption Column ◽  
Column Adsorption

This research aims are to separate of Ca and Fe metal ion in source water, with local zeolite and active carbon by adsorption column technic. Efficiency of separation are control by adsorption time and size of zeolite. Method that used was column adsorption with a flow system in which sample is applied to the filtration tube containing zeolite and active carbon. Initial and final concentrations of the samples were analyzed using Atomic Adsorption Spectrophotometer instrument. The results obtained shows that ability adsorption of zeolite to Ca and Fe metal ion are a good. Zeolite 1 (10 mesh) can reduce iron concentration until 93.98 % and zeolite 2 (5mesh) until 98.88% for 1 – 4 week range time. Whereas reducing of calcium concentration is not good, until 2 week period time adsorption of calcium ion is about 50%. Keywords: adsorption, zeolite, source water

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