ions coordinating

FTIR spectroscopy has been applied to study the coordination structures of Mg2þ and Ca2þ ions bound in Akazara scallop troponin C (TnC), which contains only a single Ca2þ binding site. The region of the COO – antisymmetric stretch provides information about the coordination modes of COO – groups to the metal ions: bidentate, unidentate, or pseudo-bridging. Two bands were observed at 1584 and 1567 cm21 in the apo state, whereas additional bands were observed at 1543 and 1601 cm21 in the Ca2þ-bound and Mg2þ-bound states, respectively.

7p system191 01-06-2013 40 2   Download

The structure of peptidase T, or tripeptidase, was deter-mined by multiple wavelength anomalous dispersion (MAD) methodology and re®ned to 2.4 A Ê resolution. Pep-tidase T comprises two domains; a catalytic domainwith an active site containing two metal ions, and a smaller domain formed through a long insertion into the catalytic domain. The twometal ions, presumablyzinc, are separatedby3.3 AÊ , and are coordinated by ®ve carboxylate and histidine ligands.

8p research12 23-04-2013 30 4   Download

The structure of the Mg 2+ -dependent enzyme human phosphoserine phosphatase (HPSP) was exploited to examine the structural and functional role of the divalent cation in the active site of phosphatases. Most interesting is the biochemical observation that a Ca 2+ ion inhibits the activity of HPSP, even in the presence of added Mg 2+ .The sixfold coordinated Mg 2+ ion present in the active site of HPSP under normal physiological conditions, was replaced by a Ca 2+ ion by using a crystallization conditionwith high concentration of CaCl2(0.7M). ...

7p dell39 03-04-2013 51 2   Download

The EF-hand protein S100A2 is a cell cycle regulator involved in tumori-genesis, acting through regulation of the p53 activation state. Metal ion-free S100A2 is homodimeric and contains two Ca 2+ -binding sites and two Zn 2+ -binding sites per subunit, whereby the Zn 2+ ion binding to one of the sites is coordinated by residues from two homodimers.

11p vinaphone15 27-02-2013 36 2   Download