Class CPSADescriptor

All Implemented Interfaces:
IDescriptor, IMolecularDescriptor

public class CPSADescriptor extends AbstractMolecularDescriptor implements IMolecularDescriptor
Calculates 29 Charged Partial Surface Area (CPSA) descriptors. The CPSA's were developed by Stanton et al. ([Stanton, D.T. and Jurs, P.C. . Analytical Chemistry. 1990. 62]) and are related to the Polar Surface Area descriptors. The original implementation was in the ADAPT software package and the definitions of the individual descriptors are presented in the following table. This class returns a DoubleArrayResult containing the 29 descriptors in the order described in the table.
A Summary of the 29 CPSA Descriptors
PPSA-1 partial positive surface area -- sum of surface area on positive parts of molecule
PPSA-2 partial positive surface area * total positive charge on the molecule
PPSA-3 charge weighted partial positive surface area
PNSA-1 partial negative surface area -- sum of surface area on negative parts of molecule
PNSA-2 partial negative surface area * total negative charge on the molecule
PNSA-3 charge weighted partial negative surface area
DPSA-1 difference of PPSA-1 and PNSA-1
DPSA-2 difference of FPSA-2 and PNSA-2
DPSA-3 difference of PPSA-3 and PNSA-3
FPSA-1 PPSA-1 / total molecular surface area
FFSA-2 PPSA-2 / total molecular surface area
FPSA-3 PPSA-3 / total molecular surface area
FNSA-1 PNSA-1 / total molecular surface area
FNSA-2 PNSA-2 / total molecular surface area
FNSA-3 PNSA-3 / total molecular surface area
WPSA-1 PPSA-1 * total molecular surface area / 1000
WPSA-2 PPSA-2 * total molecular surface area /1000
WPSA-3 PPSA-3 * total molecular surface area / 1000
WNSA-1 PNSA-1 * total molecular surface area /1000
WNSA-2 PNSA-2 * total molecular surface area / 1000
WNSA-3 PNSA-3 * total molecular surface area / 1000
RPCG relative positive charge -- most positive charge / total positive charge
RNCG relative negative charge -- most negative charge / total negative charge
RPCS relative positive charge surface area -- most positive surface area * RPCG
RNCS relative negative charge surface area -- most negative surface area * RNCG
THSA sum of solvent accessible surface areas of atoms with absolute value of partial charges less than 0.2
TPSA sum of solvent accessible surface areas of atoms with absolute value of partial charges greater than or equal 0.2
RHSA THSA / total molecular surface area
RPSA TPSA / total molecular surface area
NOTE: The values calculated by this implementation will differ from those calculated by the original ADAPT implementation of the CPSA descriptors. This is because the original implementation used an analytical surface area algorithm and used partial charges obtained from MOPAC using the AM1 Hamiltonian. This implementation uses a numerical algorithm to obtain surface areas (see NumericalSurface) and obtains partial charges using the Gasteiger-Marsilli algorithm (see GasteigerMarsiliPartialCharges). However, a comparison of the values calculated by the two implementations indicates that they are qualitatively the same.
Parameters for this descriptor:
Name Default Description
no parameters
Rajarshi Guha
Dictionary pointer(s):
CPSA in the Descriptors Dictionary [qsar-descriptors:CPSA]
Source code:
Belongs to CDK module:
Created on:
  • Constructor Details

    • CPSADescriptor

      public CPSADescriptor()
  • Method Details

    • getSpecification

      public DescriptorSpecification getSpecification()
      Description copied from interface: IDescriptor
      Returns a IImplementationSpecification which specifies which descriptor is implemented by this class. These fields are used in the map:
      • Specification-Reference: refers to an entry in a unique dictionary
      • Implementation-Title: anything
      • Implementation-Identifier: a unique identifier for this version of this class
      • Implementation-Vendor: CDK, JOELib, or anything else
      Specified by:
      getSpecification in interface IDescriptor
      An object containing the descriptor specification
    • setParameters

      public void setParameters(Object[] params) throws CDKException
      Sets the parameters attribute of the CPSADescriptor object.
      Specified by:
      setParameters in interface IDescriptor
      params - The new parameters value
      CDKException - Description of the Exception
      See Also:
    • getParameters

      public Object[] getParameters()
      Gets the parameters attribute of the CPSADescriptor object.
      Specified by:
      getParameters in interface IDescriptor
      The parameters value
      See Also:
    • getDescriptorNames

      public String[] getDescriptorNames()
      Description copied from interface: IDescriptor
      Returns an array of names for each descriptor value calculated. Many descriptors return multiple values. In general it is useful for the descriptor to indicate the names for each value. In many cases, these names can be as simple as X1, X2, ..., XN where X is a prefix and 1, 2, ..., N are the indices. On the other hand it is also possible to return other arbitrary names, which should be documented in the Javadocs for the descriptor (e.g., the CPSA descriptor). Note that by default if a descriptor returns a single value (such as ALOGPDescriptor the return array will have a single element
      Specified by:
      getDescriptorNames in interface IDescriptor
      An array of descriptor names, equal in length to the number of descriptor calculated..
    • getParameterNames

      public String[] getParameterNames()
      Gets the parameterNames attribute of the CPSADescriptor object.
      Specified by:
      getParameterNames in interface IDescriptor
      The parameterNames value
    • getParameterType

      public Object getParameterType(String name)
      Gets the parameterType attribute of the CPSADescriptor object.
      Specified by:
      getParameterType in interface IDescriptor
      name - Description of the Parameter
      The parameterType value
    • calculate

      public DescriptorValue calculate(IAtomContainer atomContainer)
      Evaluates the 29 CPSA descriptors using Gasteiger-Marsilli charges.
      Specified by:
      calculate in interface IMolecularDescriptor
      atomContainer - Parameter is the atom container.
      An ArrayList containing 29 elements in the order described above
    • getDescriptorResultType

      public IDescriptorResult getDescriptorResultType()
      Returns the specific type of the DescriptorResult object. The return value from this method really indicates what type of result will be obtained from the DescriptorValue object. Note that the same result can be achieved by interrogating the DescriptorValue object; this method allows you to do the same thing, without actually calculating the descriptor.
      Specified by:
      getDescriptorResultType in interface IMolecularDescriptor
      an object that implements the IDescriptorResult interface indicating the actual type of values returned by the descriptor in the DescriptorValue object
    • initialise

      public void initialise(IChemObjectBuilder builder)
      Default implementation of initialise allows optional override.
      Specified by:
      initialise in interface IDescriptor
      builder - chem object build