QCISD (quadratic CISD) 113, 117, 119 QSAR (quantitative structure-activity relationships) 695-706, 710, 711 cross-validation 701 deriving equation 698-70 discriminant analysis 703-5 interpreting equation 702 neural networks 703-5 principal components regression 706 -property relationship 695, 702 selecting compounds for analysis 697-8 QSPR (quantitative structure-property relationship) 695, 702 quadratic region 283-4 quadrupole 76, 181, 183, 185-6, 196 quantitative structure-activity see QSAR quantum mechanics future role 160-1 [Pg.756]

When the property being described is a physical property, such as the boiling point, this is referred to as a quantitative structure-property relationship (QSPR). When the property being described is a type of biological activity, such as drug activity, this is referred to as a quantitative structure-activity relationship (QSAR). Our discussion will first address QSPR. All the points covered in the QSPR section are also applicable to QSAR, which is discussed next. [Pg.243]

QM/MM, 198-205, 367 QSAR (quantitative structure activity relationship), 108, 114, 367. See also Structure-activity relationships QSPR (quantitative structure property relationship), 108, 308, 314, 367. See also Structure-activity relationships Quadratic configuration interaction, see QCI [Pg.378]

Quadratic synchronous transit (QST), 153 Quadrupole moment, 110 Quantitative structure activity relationship, see QSAR Quantitative stixicture property relationship, see QSPR Quantum mechanics, 10-12, 367. See also ab initio, Semiempirical Quantum Monte Carlo (QMC), 26-27, 219, 367. See also Correlation, ab initio time complexity, 130 Quasiclassical calculation, 168 Quasi-Newton, 70, 131, 152 [Pg.378]

This is the domain of establishing Structure-Property or Structure-Activity Relationships (SPR or SAR), or even of finding such relationships in a quantitative manner (QSPR or QSAR). [Pg.3]

All the techniques described above can be used to calculate molecular structures and energies. Which other properties are important for chemoinformatics Most applications have used semi-empirical theory to calculate properties or descriptors, but ab-initio and DFT are equally applicable. In the following, we describe some typical properties and descriptors that have been used in quantitative structure-activity (QSAR) and structure-property (QSPR) relationships. [Pg.390]

Furthermore, QSPR models for the prediction of free-energy based properties that are based on multilinear regression analysis are often referred to as LFER models, especially, in the wide field of quantitative structure-activity relationships (QSAR). [Pg.489]

The fundamental assumption of SAR and QSAR (Structure-Activity Relationships and Quantitative Structure-Activity Relationships) is that the activity of a compound is related to its structural and/or physicochemical properties. In a classic article Corwin Hansch formulated Eq. (15) as a linear frcc-cncrgy related model for the biological activity (e.g.. toxicity) of a group of congeneric chemicals [37, in which the inverse of C, the concentration effect of the toxicant, is related to a hy-drophobidty term, FI, an electronic term, a (the Hammett substituent constant). Stcric terms can be added to this equation (typically Taft s steric parameter, E,). [Pg.505]

Quantitative Structure—Activity Relationships. Many quantitative stmcture—activity relationship (QSAR) studies of progestins have appeared in the Hterature and an extensive review of this work is available (174). QSAR studies attempt to correlate electronic, steric, and/or hydrophobic properties to progestational activity or receptor binding affinity. A review focusing on the problems associated with QSAR of steroids has been pubUshed (175). [Pg.220]

Computers have greatly enhanced the speed and accuracy of the predictive nature of QSAR, however they are only tools to aid investigation and elucidation of the relationship between structure and properties. A clear understanding of the system and the fundamental questions that need to be answered are still a requirement for future research. [Pg.32]

Lipophilicity is the measure of the partitioning of a compound between a lipidic and an aqueous phase [1]. The terms lipophilicity and hydrophobicity are often used inconsistently in the literature. Lipophilicity encodes most of the intramolecular forces that can take place between a solute and a solvent. Hydrophobicity is a consequence of attractive forces between nonpolar groups and thereby is a component of lipophilicity [2]. Lipophilicity is one of the most informative physicochemical properties in medicinal chemistry and since long successfully used in quantitative structure-activity relationship (QSAR) studies. Its [Pg.357]

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