DESIGNING PEPTIDE BY MOLECULAR RECOGNITION THEORY AS AFFINITY ADSORPTION LIGAND FOR PEPTIDE PURIFICATION IN AFFINITY-CHROMATOGRAPHY

An ''antisense'' peptide corresponding to the ''sense'' peptide, angio tensin II, was designed by the Molecular Recognition Theory (MRT) and synthesized by the solid phase peptide synthesis method. The complemen tarity of peptides specified by ''sense'' and ''antisense'' strands of DNA of MRT were adapted in a computer program and the Kyte and Doolit tle's hydropathy scoring system was used as the hydrophobicity indicat or of amino acids in this study. The prototypical system used for eval uating the interaction between such peptide pairs involved testing for the binding of angiotensin II (AII) and its antisense peptide, AII-AS (Ile-Ala-Asn-Val-Asn-Met-Gly-Glu). AII-AS peptide was attached to EAH -Sepharose 4B support, and the binding constants between AII-AS with A II and with AII antagonist ([Ser1, Ile8]-AII) were respectively determ ined. The higher binding affinity between AII antagonist with AII-AS w as also supported by a preliminary molecular modeling calculation. A m athematical modeling for affinity chromatography was adapted to compar e the experimental results and to demonstrate the effects of the pore diffusion as the rate determining step on the performance of the anti- sense affinity column. The results of this study could provide a novel approach to affinity ligand design for bioseparation by MRT and molec ular modeling.