The CCP4 suite: integrative software for macromolecular crystallography.

The Collaborative Computational Project No. 4 (CCP4) is a UK-led international collective with a mission to develop, test, distribute and promote software for macromolecular crystallography. The CCP4 suite is a multiplatform collection of programs brought together by familiar execution routines, a set of common libraries and graphical interfaces.

'': High-Resolution Crystal Structures of Ligand-Protein Complexes Need Not Always Represent Confident Binding Poses.

Our understanding of the structure-function relationships of biomolecules and thereby applying it to drug discovery programs are substantially dependent on the availability of the structural information of ligand-protein complexes. However, the correct interpretation of the electron density of a small molecule bound to a crystal structure of a macromolecule is not trivial. Our analysis involving quality assessment of ~0.

Likelihood-based estimation of substructure content from single-wavelength anomalous diffraction (SAD) intensity data.

SAD phasing can be challenging when the signal-to-noise ratio is low. In such cases, having an accurate estimate of the substructure content can determine whether or not the substructure of anomalous scatterer positions can successfully be determined. Here, a likelihood-based target function is proposed to accurately estimate the strength of the anomalous scattering contribution directly from the measured intensities, determining a complex correlation parameter relating the Bijvoet mates as a function of resolution.

Phasertng: directed acyclic graphs for crystallographic phasing.

Crystallographic phasing strategies increasingly require the exploration and ranking of many hypotheses about the number, types and positions of atoms, molecules and/or molecular fragments in the unit cell, each with only a small chance of being correct. Accelerating this move has been improvements in phasing methods, which are now able to extract phase information from the placement of very small fragments of structure, from weak experimental phasing signal or from combinations of molecular replacement and experimental phasing information. Describing phasing in terms of a directed acyclic graph allows graph-management software to track and manage the path to structure solution.

Factors influencing estimates of coordinate error for molecular replacement.

Good prior estimates of the effective root-mean-square deviation (r.m.s.

Seeing but not believing: the structure of glycerol dehydrogenase initially assumed to be the structure of a survival protein from Salmonella typhimurium.

The determination of the crystal structure of a mutant protein using phases based on a previously determined crystal structure of the wild-type protein is often a straightforward molecular-replacement protocol. Such a structure determination may be difficult if there are large-scale structural differences between the wild-type and mutant proteins. In this manuscript, an interesting case is presented of the unintentional crystallization of a contaminant protein which shared some structural features with the presumed target protein, leading to difficulties in obtaining a completely satisfactory molecular-replacement structure solution.

Structure determination of contaminant proteins using the MarathonMR procedure.

In the recent decades, essential steps of protein structure determination such as phasing by multiple isomorphous replacement and multi wave length anomalous dispersion, molecular replacement, refinement of the structure determined and its validation have been fully automated. Several computer program suites that execute all these steps as a pipeline operation have been made available. In spite of these great advances, determination of a protein structure may turn out to be a challenging task for a variety of reasons.

Determination of crystal structures of proteins of unknown identity using a marathon molecular replacement procedure: structure of Stenotrophomonas maltophilia phosphate-binding protein.

During the past decade, the authors have collected a few X-ray diffraction data sets from protein crystals that appeared to be easy cases of molecular replacement but failed to yield structures even after extensive trials. Here, the use of a large-scale molecular replacement method that explores all structurally characterized domains as phasing models to determine the structure corresponding to two data sets collected at 1.9 and 2.

CANDO and the infinite drug discovery frontier.

The Computational Analysis of Novel Drug Opportunities (CANDO) platform (http://protinfo.org/cando) uses similarity of compound-proteome interaction signatures to infer homology of compound/drug behavior. We constructed interaction signatures for 3733 human ingestible compounds covering 48,278 protein structures mapping to 2030 indications based on basic science methodologies to predict and analyze protein structure, function, and interactions developed by us and others.

NeeMDB: Convenient Database for Neem Secondary Metabolites.

Indian Neem tree is known for its pesticidal and medicinal properties for centuries. Structure elucidation of large number of secondary metabolites responsible for its diverse properties has been achieved. However, this data is spread over various books, scientific reports and publications and difficult to access.

Synthesis, anticancer and antioxidant activities of 2,4,5-trimethoxy chalcones and analogues from asaronaldehyde: structure-activity relationship.

2,4,5-Trimethoxy chalcones and analogues were synthesized from asaronaldehyde derived from β-asarone. These novel compounds when tested against three human tumour cell lines (MCF-7, SW-982 and HeLa) using MTT assay, revealed that chalcones possessing electron donor groups in para position to carbonyl moiety of phenyl ring A, showed better inhibitory activity (2, 3, 4, 6, 7, 10, 17). When evaluated for antioxidant activities, compound 15 exhibited better free radical scavenging property in DPPH assay while compounds 2, 3, 5, 7, 9, 10, 11, 16, and 18 showed significant NO scavenging activity.

Structural and functional analyses of a saturated acyl ACP thioesterase, type B from immature seed tissue of Jatropha curcas.

The distinguishing structural and functional domains of plant acyl-acyl carrier protein (ACP) thioesterases and their complex interaction with the ACP-linked fatty acid substrate complex have remained elusive. E. coli based heterologous expression and characterisation of many plant thioesterases reported so far have not been extended and linked to in silico modelling studies to explain the diversity in plant thioesterase substrate specificities.

Abyssinones and related flavonoids as potential steroidogenesis modulators.

Abyssinones and related flavonoids were screened against 3 enzymes (3betaHSD, 17betaHSD and Aromatase) of steroidogenesis pathway. The virtual screening experiment shows high affinity for flavonones than their respective chalcones. A 4' -OH blocked prenylated flavonone 2b (2-(2', 2'-dimethyl chroman-6'-yl)-7-hydroxy chroman-4-one) had consistent binding affinity to all the three enzymes used in this study showing higher binding affinity to aromatase.