The water molecule

Single-crystal X-ray structure determinations of the complex between the minor-groove binder distamycin and d(GGCCAATTGG) reveal two 1 : 1 binding modes which differ in the orientation of the drug molecule in the minor groove. The two crystals were grown from different crystallization conditions and found to diffract to 2.38 and ˚ 1.85 A, respectively. The structures were refined to completion using SHELXL-93, resulting in a residual R factor of ˚ 20.30% for the 2.38-A resolution structure (including 46 ˚ water molecules) and 19.74% for the 1.

10p system191 01-06-2013 30 5   Download

Department of Chemistry ‘IFM’, University of Torino, Italy; 2Department of Biology, University ‘Roma Tre’, Rome, Italy; 3Department of Structural and Functional Biology, University of Insubria, Italy Haem binding to human serum albumin (HSA) endows the protein with peculiar spectroscopic properties. Here, the effect of ibuprofen and warfarin on the spectroscopic properties of ferric haem –human serum albumin (ferric HSA–haem) and of ferrous nitrosylated haem –human serum albumin (ferrous HSA –haem-NO) is reported.

7p system191 01-06-2013 46 3   Download

Human serum albumin (HSA) is best known for its extraordinary ligand binding capacity. HSA has a high affinity for heme and is responsible for the transport of medium and long chain fatty acids. Here, we report myri-state binding to the N and B conformational states of Mn(III)heme–HSA (i.e. at pH 7.0 and 10.0, respectively) as investigated by optical absorbance and NMR spectroscopy. At pH 7.0, Mn(III)heme binds to HSA with lower affinity than Fe(III)heme, and displays a water molecule coordinated to the metal....

12p fptmusic 12-04-2013 45 4   Download

The structure of the complex between the minor groove binder netropsin and d(GGCCAATTGG) was determined via single-crystal X-ray tech-niques. The structure was refined to completion usingrefmac5.1.24, result-ing in a residual R-factor of 20.0% (including 68 water molecules). Using crystal engineering and cryocooling techniques, the resolution could be enhanced to 1.75 A ˚ , resulting in an unambiguous determination of the drug conformation and orientation.

11p fptmusic 11-04-2013 34 2   Download

This paper reports the results obtained using the osmotic stress method applied to the purified cathodic and anodic hemoglobins (Hbs) from the catfishHoplosternum littorale, a species that displays facultative accessorial air oxygen-ation. We demonstrate that water potential affects the oxy-gen affinity ofH. littoraleHbs in the presence of an inert solute (sucrose). Oxygen affinity increases when water activity increases, indicating that water molecules stabilize thehigh-affinitystateof theHb.

0p awards 05-04-2013 41 3   Download

The catalytic mechanism underlying the aminopeptidase fromStreptomyces griseus (SGAP) was investigated. pH-dependent activity profiles revealed the enthalpy of ionization for the hydrolysis of leucine-para-nitroanilide by SGAP. The value obtained (30 ± 5 kJÆmol )1 ) is typical of a zinc-bound water molecule, suggesting that the zinc-bound water⁄hydroxide molecule acts as the reaction nucleophile.

13p galaxyss3 21-03-2013 65 4   Download

Here, we report for the first time quinol peroxidase (QPO), an enzyme that uses ubiquinol-1 as an electron donor for the reduction of H2O2 to water. We purified QPO to 90% purity from the membrane fraction ofActino-bacillus actinomycetemcomitans. QPO is a 53.6-kDa protein that contains three heme c molecules. Theqpogene was predicted to encode a putative bacterial cytochromec peroxidase with N-terminal extensions containing an additional potential hemec-binding motif.

14p galaxyss3 21-03-2013 34 3   Download

The invariant carboxylate residue which follows the Walker B motif (hyd4DE⁄D) in the nucleotide-binding domains (NBDs) of ATP-binding cassette transporters is thought to be involved in the hydrolysis of the c-phosphate of MgATP, either by activating the attacking water molecule or by promoting substrate-assisted catalysis.

13p galaxyss3 07-03-2013 30 5   Download

Special Topics I. Selenium Ecotoxicology II. Arsenic in Drinking Water Principles of Environmental Toxicology Instructor: Gregory Möller, Ph.D. University of Idaho. Examine the chemistry of selenium in inorganic and organic molecules. Understand the role of seleno-amino acids in the expression of selenium toxicity in plant and animal systems. Examine chronic selenium toxicosis (selenosis). Understand the role of selenium in reproductive failure.

11p nguyenvanquan037 07-01-2011 92 10   Download