a thermodynamic study on the interaction between zinc ion (zn2+) and human growth hormone(hgh) was studied at two temperatures of 27c and 37c in aqueous solution using an isothermal titrationcalorimetry. it was found that there is a set of three identical and non-interacting binding sites for zn2+ ions. the intrinsic dissociation equilibrium constant and the molar enthalpy of binding are 1.54...

The COP1 gene of Arabidopsis thaliana encodes a protein mediating the switch between the two developmental pathways utilized in light and darkness. A cysteine-rich motif identified the COP1 protein as a member of a group of regulatory proteins which share the amino acid motif Cys-X-X-Cys-loop I-Cys-X-His-X-X-Cys-X-X-Cys-loop II-Cys-X-X-Cys (ring finger). Although this new class of cysteine-rich...

Stromal interaction molecule 1 (STIM1) is responsible for activating the Ca(2+) release-activated Ca(2+) (CRAC) channel by first sensing the changes in Ca(2+) concentration in the endoplasmic reticulum ([Ca(2+)](ER)) via its luminal canonical EF-hand motif and subsequently oligomerizing to interact with the CRAC channel pore-forming subunit Orai1. In this work, we applied a grafting approach to...

Calcium (Ca⁺²) is a ubiquitous messenger in eukaryotes including Caenorhabditis. Ca⁺²-mediated signalling processes are usually carried out through well characterized proteins like calmodulin (CaM) and other Ca⁺² binding proteins (CaBP). These proteins interact with different targets and activate it by bringing conformational changes. Majority of the EF-hand proteins in Caenorhabditis contain C...

In biological systems, X-ray absorption spectroscopy (XAS) can determine structural details of metal binding sites with high resolution. Here a method enabling an automated analysis of the corresponding EXAFS data is presented, utilizing in addition to least-squares refinement the prior knowledge about structural details and important fit parameters. A metal binding motif is characterized by th...

Apotransferrin (apo Tf)  in 0.1 M N-(2hydroxyethyl)piperazine-N2-ethanesulfanic acid at 25 ˚C  and pH 7.4 has been titrated with acidic solution of Tb3+. The binding of Tb3+ at  the two specific metal-binding sites of transferrin was followed from the changes in the difference UV spectra at 245 nm. The molar absorptivity per binding site for Tb3+...

The LAGLIDADG homing endonucleases include free-standing homodimers, pseudosymmetric monomers, and related enzyme domains embedded within inteins. DNA-bound structures of homodimeric I-CreI and monomeric I-SceI indicate that three catalytic divalent metal ions are distributed across a pair of overlapping active sites, with one shared metal participating in both strand cleavage reactions. These ...

Toxic metals are known to inhibit DNA repair but the underlying mechanisms of inhibition are still not fully understood. DNA repair enzymes such as human uracil-DNA glycosylase (hUNG) perform the initial step in the base excision repair (BER) pathway. In this work, we showed that cadmium [Cd(II)], a known human carcinogen, inhibited all activity of hUNG at 100 μM. Computational analyses based o...

We have produced and characterized two new copper-transporting ATPases, CtrA2 and CtrA3 from Aquifex aeolicus, that belong to the family of heavy metal ion-transporting P(IB)-type ATPases. CtrA2 has a CPC metal-binding sequence in TM6 and a CxxC metal-binding N-terminal domain, while CtrA3 has a CPH metal-binding motif in TM6 and a histidine-rich N-terminal metal-binding domain. We have cloned ...

The rubella virus (RUB) nonstructural protein (NS) open reading frame (ORF) encodes a polypeptide precursor that is proteolytically self cleaved into two replicase components involved in viral RNA replication. A putative EF-hand Ca(2+)-binding motif that was conserved across different genotypes of RUB was predicted within the nonstructural protease that cleaves the precursor by using bioinforma...