CHARACTERISTIC INTERACTION OF CA2- ION-TRANSPORT STUDY ACROSS COACERVATE LAYERS OF ALPHA-ELASTIN AND ELASTIN MODEL POLYPEPTIDE, (VAL-PRO-GLY-VAL-GLY)(N)( IONS WITH ELASTIN COACERVATE )

Ion transport characteristics across a macrocoacervate layer membrane composed of aqueous elastin model polypeptides with a specific repeati ng pentapeptide sequence, H-(Val-Pro-Gly-Val-Gly)(n)-Val-OMe (n greate r than or equal to 40), were investigated. Transmembrane potential res ponses for NaCl, MgCl2, and CaCl2 concentration-cell systems were meas ured and examined systematically by comparing with those across a coac ervate membrane composed of bovine neck ligamental alpha-elastin. In t he case of the NaCl and MgCl2 systems, potential responses across thes e protein liquid membranes were different noticeably from each other d epending upon the molecular structure with and without charged peptide side chains, whereas in the CaCl2 systems the transmembrane potential responses across the noncharged polypentapeptide coacervate membrane were comparable with those across the alpha-elastin coacervate membran e carrying both the positively and negatively charged amino acid resid ues as an amphoteric ion-exchange membrane. These results indicated th at mechanisms of major Ca2+ ion transport ave based on the specific an d selective interactions With electrically neutral sites of elastin, s uch as the polypentapeptide backbone chain. (C) 1996 John Wiley & Sons , Inc.