Accession Number : ADA185509

Title :   Dielectric Relaxation Studies on Analogs of the Polypentapeptide of Elastin,

Corporate Author : ALABAMA UNIV IN BIRMINGHAM LAB OF MOLECULAR BIOPHYSICS

Personal Author(s) : Buchet, Rene ; Luan, Chi-Hao ; Prasad, Kari U ; Harris, R D ; Urry, Dan W

PDF Url : ADA185509

Report Date : Jan 1987

Pagination or Media Count : 33

Abstract : Dielectric measurements of the complex permittivity of coacervate concentrations of two analogs of the polypentapeptide of elastin, were taken over the frequency range of 1 MHz to 1000 MHz and over the temperature range of 0 to 60 C. Two relaxation processes were observed in each polypentapeptide. One with a frequency centered in the low MHz frequency range which has been attributed to a low frequency librational mode within the polypeptide. The other relaxation is located near the GHz frequency range. The magnitude of the dielectric increment of the librational mode of each polypentapeptide analog increases with increasing temperature from near zero at 0 c to approximately 40 at 60 C, showing an inverse temperature transition to a more-ordered structure. Conversely the magnitudes of the dielectric increment of the high frequency relaxation decrease on increasing the temperature and differ in approximate proportion to the hydrophobicity of the pentamer for the polypentapeptide of elastin and the two analogs at temperatures below the inverse temperature transition. It is suggested that clathrate-like water surrounding hydrophobic side chains contributes to the high frequency relaxation.

Descriptors :   *ALBUMINOIDS, *DIELECTRIC PROPERTIES, *RELAXATION, ANALOGS, DIELECTRICS, FREQUENCY, HIGH FREQUENCY, HYDROPHOBIC PROPERTIES, INVERSION, LOW FREQUENCY, MEASUREMENT, RANGE(EXTREMES), TEMPERATURE, TRANSITIONS, WATER, HYDROGEN BONDS

Subject Categories : Organic Chemistry
      Biochemistry
      Physical Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE