Databases chiral structures

StereoPlex connects UNITY and CombiLibMaker often using CONCORD to rapidly generate high quahty 3D coordinate sets for the compounds entered into the databases or combinatorial hbraries. With StereoPlex new combinatorial hbraries containing chiral structures can be vahdated, enhanced and expanded by using a combination of StereoPlex and CONCORD. 

Ligand preparation and database maintenance can be divided into several subtopics. Ligands need to be represented as chemical data structures. Some ligands may require multiple structures, with comprehensive representation requiring treatment of chirality and/or tautomerization and/or protonation state(s). Dependent on the intended use ofthe database, each structure may further require elucidation of one or more 3D conformers. Each of the resultant representations may then be annotated with various types of information, for example, conformational energy, MW, purchase or synthesis source, and amount of physical compound available. This body of information must then be stored as completely and as compactly as possible. In this section, we explore and comment on some of these aspects of virtual ligand preparation. 

The chapters on stereochemistry are ones by Nancy Porter, concerning a chiral structure database for saccharides (the subject of her research before she joined Maxwell Online) and two by various authors from Chemical Abstracts Service, representing presentations at Noordwijkerhout by Paul Blower, about the addition... 

The need for an overall and combined chemical structure and data search system became clear to us some time ago, and resulted in the decision to build CHIRBASE, a molecular-oriented factual database. The concept utilized in this database approach is related to the importance of molecular interactions in chiral recognition mechanisms. Solely a chemical information system permits the recognition of the molecular key fingerprints given by the new compound among thousands of fingerprints of known compounds available in a database. 

In this chapter, we will discuss the present status of CHIRBASE and describe the various ways in which two (2D) or three-dimensional (3D) chemical structure queries can be built and submitted to the searching system. In particular, the ability of this information system to locate and display neighboring compounds in which specified molecular fragments or partial structures are attached is one of the most important features because this is precisely the type of query that chemists are inclined to express and interpret the answers. Another aspect of the project has been concerned with the interdisciplinary use of CHIRBASE. We have attempted to produce a series of interactive tools that are designed to help the specialists or novices from different fields who have no particular expertise in chiral chromatography or in searching a chemical database. 

More than 100 CSPs are commercially available nowadays, which should make the separation of any pair of enantiomers feasible. However, the enantiorecognition mechanisms involved in the chiral recognition between the analytes and the CSPs are complex and therefore the selection of the appropriate CSPs, depending on the structure of the analyte, is a difficult task. A common approach to develop a new enantioseparation is the stepwise trial-and-error approach based on detailed consideration of the enantiorecognition mechanisms between the chiral selector and the analyte, or on the analyst s experience, or on the consultation of literature or databases. However, this approach is time-consuming and often unsuccessful owing to the fact that achieving enantioresolution is often purely empirical... 

Figure 2.150. Ligprep is used for the rapid conversion of 2D structure files into accurate 3D models suitable for use in database screens and other applications. At the user s discretion Ligprep can generate multiple protonation states, enumerate chiralities, and generate tautomeric forms of the ligand...

Tel. 514-343 6738, fax 514-343-5728, e-mail hanessia ere.umontreal.ca Analysis and perception of stereochemical features in molecules and selection from a database of chiral precursors for total syntheses. 2D-to-3D structure conversion. Macintosh, Silicon Graphics, VAX. ChemProtect for selection of appropriate protective groups in more than 150 reaction conditions. Macintosh. 

Roussel, C., Piras, P. and Heitmann, I. (1997). An Approach to Discriminating 25 Commercial Chiral Stationary Phases from Structural Data Sets Extracted from a Molecular Database. Biomedical Chromatography, 11,311-316. 

Roussel, C., Piras, P., Heitmann, I. An approach to discriminating 25 commercial chiral stationary phases from structural data sets extracted from a molecular database, Biomed. Chromatogr., 1997, 11, 311-316. 

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