Score with physico-chemical properties

These are autocovariances and cross-covariances calculated from sequential data with the aim of transforming them into uniform-length descriptors suitable for QSAR modeling. ACC transforms were originally proposed to describe peptide sequences [Wold, Jonsson et al, 1993 Sjbstrbm, Rannar et al., 1995 Andersson, Sjostrom et al., 1998 Nystrom, Andersson et al., 2000]. To calculate ACC transforms, each amino acid position in the peptide sequence is defined in terms of three orthogonal z-scores, derived from a Principal Component Analysis (PC A) of 29 physico-chemical properties of the 20 coded amino acids. 

Fig. 4.4 LC-TOF MS spectra and accurate measurements for the secondary amides of alachlor (a) and acetochlor (b) sulfonic acid in a groundwater sample. The correct elemental composition for both analytes ranks at the second score position. The physico-chemical properties and the chromatographic retention times were predicted from the molecular structure (Ferrer and Thurman 2003, Fig. 4.3, with permission)...

Using our simplified protein models, we defined descriptors in a set particularly well adapted to the peaks. For this, we combined the peak properties - electron density, anisotropic volume etc. - with the physico-chemical characteristics of the molecular subunits associated with each peak [12]. In this scoring function ... 

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