The use of various properties of amino acids in color and monochrome dot-matrix analyses for protein homologies.

ABSTRACT

Software has been developed to allow the use of a number of parameters in the comparative representation of proteins in color and monochrome dot matrices. They include the parameters of partial specific volume, residue bulkiness, the mean area buried of side chains, seven additional hydropathy scales, mutability, polarity, secondary structure propensities, energy/residue, energy/atom, Rf values, the pKs at the N and C terminals, user-defined parameters and, if desired, randomly generated values. Many of these parameters can be combined in n space using an algorithm based on the Euclidian distance relationship in order to derive consensus values. The problem of scoring matched identities is addressed and the user may stipulate that they score 100 on a 0-100 scale or be determined from the Dayhoff MDM78 values with the rest of the matrix scaled appropriately. The PAMs matrix has been incorporated in such a way to allow the user to stipulate various PAM's values or estimated percentage difference between two peptide sequences, and converting to log odds values. In addition, the similarity ring developed by Swanson and the matrix proposed by Bacon and Anderson have been adapted for use in the program. Color indices have been utilized to give a 'third dimension' to the projections, allowing the user to judge the degree of similarity of different regions which are represented. The software also provides for the plotting of nucleotides in which case color is used to code individual nucleotides, purines versus pyrimidines, or similar colors are used to differentiate between A and T bases on the one hand, and G and C on the other.