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Through an expansive international effort that involved data collection on 12 small-angle X-ray scattering (SAXS) and four small-angle neutron scattering (SANS) instruments, 171 SAXS and 76 SANS measurements for five proteins (ribonuclease A, lysozyme, xylanase, urate oxidase and xylose isomerase) were acquired. From these data, the solvent-subtracted protein scattering profiles were shown to be reproducible, with the caveat that an additive constant adjustment was required to account for small errors in solvent subtraction. Further, the major features of the obtained consensus SAXS data over the q measurement range 0-1 Å-1 are consistent with theoretical prediction. The inherently lower statistical precision for SANS limited the reliably measured q-range to 2.2 Å-1 showed good mutual agreement, affirming that this region has interpretable features for structural modelling. SAS measurements with inline size-exclusion chromatography (SEC) proved to be generally superior for eliminating sample heterogeneity, but with unavoidable sample dilution during column elution, while batch SAS data collected at higher concentrations and for longer times provided superior statistical precision. Careful merging of data measured using inline SEC and batch modes, or low- and high-concentration data from batch measurements, was successful in eliminating small amounts of aggregate or interparticle interference from the scattering while providing improved statistical precision overall for the benchmarking data set.

The study was conducted to know the effect of metal substitution on the activity and structure of the aminopeptidase P (APPro) from Escherichia coli. The result reveals that excess Zn presence demonstrates a third party metal-binding site, formed by two conserved His residues and the dipeptide inhibitor and Zn atom bound at such a site would stabilize product binding and enhance inhibition.

A study was conducted on mutant proteins C6S, C9S, C39S and C42S of CP rRd. The cytesine ligand in each of the mutant has been substituted, in turn, by serine. Four geometric isomers were developed in which FeOS3 centers are introduced differently within the same protein chain. Results showed that the differences in the nature of Fe-O gamma-Ser bonds caused by variation of the conformational flexibility of the protein chains carrying the ligands are responsible for the differences in reduction potentials and pH dependence as well as the onset irreversible behavior in the electron transfer of the four mutant proteins.

Recombinant human diamine oxidase (hDAO) is heterologously expressed in Drosophila S2 cells and the studies have shown that the purified hDAO contains substoichiometric amounts of copper and topaquinone cofactor (TPQ). X-ray diffraction data recorded below the copper edge, between the copper and zinc edges and above the zinc edge have shown that the metal site is occupied 75% by copper and 25% by zinc and the formation of the TPQ cofactor is correlated with copper occupancy.

The product of the AOC1 gene known as diamine oxidase (hDAO) is cloned and expressed in insect cells and its structure is determined by X-ray crystallography to a resolution of 1.8 [Angstrom]. The findings for inhibitor binding of hDAO suggested that an aspartic acid residue is conserved in all diamine oxidases but absent from other amine oxidases and is responsible for the diamine specificity by interacting with the second amino group of preferred diamine substrates.

The article explains the phenomenon associated with the inhibition of copper amine oxidase from Arthrobacter globiformis (AGAO) by using the enantiomer-specific binding of ruthenium(II) molecular wires. The discussed inhibition is shown to exhibit a high degree of selectivity, which is not obtained by other wires.

The purification, structural characterization and kinetic and biochemical analysis of Orotidine 5'-monophosphate (OMP) decarboxylase from Plasmodium falciparum (PfODCase) is described. The structure of PfODCase solved in the absence of ligand displays a classic TIM-barrel fold characteristic of the enzyme.

The site-directed mutagenesis and X-ray crystallography were employed to investigate the role of the surface loop movement of Escherichia coli dihydroorotase in catalysis. The kinetic and structural analyses suggest that Thr109 and Thr110 in the flexible loop provide productive binding of substrate and stabilize the transition-state intermediate, thereby increasing catalytic activity.

Aminopeptidase P (APPro) is a manganese-dependent enzyme that cleaves the N-terminal amino acid from polypeptides where the second residue is proline. Appro shares a similar fold, substrate specificity, and catalytic mechanism with methionine aminopeptidase and prolidase.

A series of compounds derived from the substrate analogue of copper amine oxidases (CuAOs) are screened against six different CuAOs in order to design potent and selective inhibitors and the substrate analogues investigated were the family of 4-(aryloxy)-2-butynamines. The structural and inhibition results support the feasibility of designing selective mechanism-based inhibitors of copper amine oxidases.

The structure of prolidase from Pyrococcus furiosus (Pfprol) is solved and refined at 2.0 angstrom resolution. The crystal structure of Pfprol is solved using multiple-wavelength anomalous dispersion, which produced diffraction data of relatively high quality and resolution.

Commensal bacteria serve as an important line of defense against colonisation by opportunisitic pathogens, but the underlying molecular mechanisms remain poorly explored. Here, we show that strains of a commensal bacterium, Haemophilus haemolyticus, make hemophilin, a heme‐binding protein that inhibits growth of the opportunistic pathogen, non‐typeable Haemophilus influenzae (NTHi) in culture. We purified the NTHi‐inhibitory protein from H. haemolyticus and identified the hemophilin gene using proteomics and a gene knockout. An x‐ray crystal structure of recombinant hemophilin shows that the protein does not belong to any of the known heme‐binding protein folds, suggesting that it evolved independently. Biochemical characterisation shows that heme can be captured in the ferrous or ferric state, and with a variety of small heme‐ligands bound, suggesting that hemophilin could function under a range of physiological conditions. Hemophilin knockout bacteria show a limited capacity to utilise free heme for growth. Our data suggest that hemophilin is a hemophore and that inhibition of NTHi occurs by heme starvation, raising the possibility that competition from hemophilin‐producing H. haemolyticus could antagonise NTHi colonisation in the respiratory tract. [ABSTRACT FROM AUTHOR]