Document Type
Dissertation
Date of Award
1977
Abstract
A combination of the techniques of differential and zonal centrifugation were used to isolate high purity fractions of plasma membrane fragments from homogenates of adult and 5 month fetal bovine liver. Discontinuous sucrose density gradients were used during zonal centrifugation which yielded two fractions of plasma membrane from each source. In both the adult and fetal samples a light plasma membrane fraction banded at 33 percent sucrose, density 1.146, while a heavier fraction was found at 38 percent sucrose, density 1.172.The plasma membrane fractions were identified by enzymatic analyses of (Na+ +K+ )-ATPase and 5’-nucleotidase activities. Following purification of the zonal fractions by flotation and washing, the plasma membrane fractions from adult bovine liver were enriched in (Na++K+)-ATPase by factors of 78.29 and 60.99 for the light and heavy fractions respectively over the starting sample. The enrichment in (Na++K+)-ATPase of fetal plasma membranes was found to be 69.56 and 61.00 respectively for the light and heavy fractions.Chemical analyses showed the plasma membranes to have high sialic acid and cholesterol content. The ratio of cholesterol to phospholipid content in both adult and fetal membrane was approximately 0.70 and 0.50 for the light and heavy fractions, respectively.Analysis of sedimentation coefficients showed that the plasma 4 membrane had values ranging from 0.477 to 1.477 x 104.The mean equilibrium densities of the plasma membranes in sucrose were, respectively, 1.150 and 1.175 for the light and heavy fractions of the adult system, while the corresponding fractions in the fetal system had values of 1.157 and 1.178. The mean equilibrium densities in CsC1 were determined to be 1.193 and 1.227 for the light and heavy plasma membranes respectively in the adult system while the corresponding fractions from the fetal system had values of 1.164 and 1.220. Analysis of the plasma membranes by SDS-polyacrylamide gel electrophoresis revealed significant differences in protein composition. It was determined that the sub fractions from both sources were qualitatively different in both polypeptide and glycopeptide composition and that unique qualitative differences in polypeptide and glycopeptide composition existed between the adult and fetal plasma membranes. The differences observed in the protein composition of the adult and fetal cells possibly reflect phase-specific proteins of the plasma membrane of cells at different stages of differentiation.
Recommended Citation
Edwards, Jesse J., "A Biochemical and Biophysical Comparison of Fetal and Adult Bovine Liver Plasma Membranes." (1977). All ETDs from UAB. 7115.
https://digitalcommons.library.uab.edu/etd-collection/7115
Comments
PhD - ProQuest publication number 7904254