Search

Research has been conducted on the phosphate binding to ZnZn-Streptomyces dizinc aminopeptidase and its Co (super)2+ -substituted derivatives. The details of the nuclear magnetic resonance relaxation and kinetic studies of this binding are presented.

Research has been conducted on the metal-dependent peptide antibiotic. Nuclear magnetic resonance studies of the metal complex structure via paramagnetic Co(II) probe are described.

Results demonstrate use of paramagnetic metal ion cobalt(II) as an NMR probe in structural studies of the synthetic macromolecules such as dendrimers to identify metal recognition sites.

Several sharp, well resolved hyperfine shifted H NMR signals were seen in the 70 to -20 ppm chemical shift range of the hyperactive Cu(II)substituted aminopeptidase from Aeromonas proteolytica (AAP). This is due to spin-coupling of two CU(II) ions. The stronger downfield shifted signals were assigned to imidazole N-H protons of two coordinated histidine residues.

A study on the binding of various lanthanide(II) ions to anthracycline antitumor antibiotics such as daunomycin and adriamycin was conducted. The binding of the ions and the antibiotics was aided by methanol and aqueous solutions. Optical and 2D nuclear magnetic resonance techniques were utilized. Results revealed that the drug complex, which underwent slow chemical exchange with each other, dominated the metal-to-ligand binding ratio.

NMR studies of the paramagnetic Fe(II)BLM identified the ligands to the metal center in the Fe(II) adduct of bleomycin as derived from the beta-aminoalanine, the pyrimidinylpropionamide and the beta-hydroxyhistidine segments. Two-dimensional NMR techniques also allowed the identification of many of the spin networks present in the NMR spectrum of the paramagnetic Fe(II)BLM. Moreover, they clarify the assignments for the signals between -0.8 and -20 ppm. Examination of the NMR data reveals that alpha-methylvalerate and/or mannose segments do not participate in Fe(II) complexation.

Absorption and circular dichroism spectroscopic studies on Co(II)-substituted Escherichia coli ribonucleotide reductase R2 reveal that the structurally well-defined R2 metal ion binding sites constrain divalent metal ion binding to native sites. The Co-R2 complexes Co(II) centers are pentacoordinate and magnetically uncoupled. The Co(II) center characteristics resemble those of active site-bound Mn(II).

Research into the mobility and cooperativity of dendritic arms in the Co(II) complexes of a number of 2,6-diamidopyridines is presented.

Research was conducted to examine the characterization of a possible Ni metallochaperone related to urease. Site-directed mutagenesis techniques were used to create variants of H144 UreE to identify the metal-binding ligands. NMR spectroscopy demonstrated that His96 and His110 served as ligands to Ni or Co. Results indicate that residues Asp111 and His96, which are associated with the first site of Ni binding, are highly conserved.