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Biomedical subjects

A G Walton

Publications and source records attributed to A G Walton.

12 recordsLinked to original sources
PubMed1979

Platelet interaction with synthetic copolypeptide films.

Kinetic and equilibrium studies of blood platelet binding to copolypeptide films show that attachment and serotonin release are not dependent upon the composition of the copolypeptide. Data may be explained by postulating that platelets frequently collide elastically with the surface but leave behind material that modifies subsequent behavior. Similarly, material released from platelets adsorbs at the interface and the extent of attachment and serotonin release are modified and controlled by these adsorbed species. Basically, if the platelet is exposed to a clean surface, its collision with the surface leads to activation and release. In the presence of inert protein, the collision is cushioned by the protein and platelets do not attach or release to any extent. Finally, if protein (or other entities) released from the platelet provide attachment sites, then attachment occurs without release. It is postulated that the behavior of platelets at surfaces is controlled by these interrelated processes.

Biocompatible Materials↗
PubMed1977

An analysis of molecular interactions involved in the assembly of tropomyosin tactoids.

Arrangements of parallel and antiparallel tropomyosin molecules are examined for residue interactions which might explain the paracrystal forms observed by electron microscopy. Molecular arrays which produce interaction maxima and corresponding computer graphics-simulated staining patterns are compared with observd electron micrographs. The best correlation of interactions with staining pattern occurs when cationic bridging of acid residues is maximized and supported by favourable ion pair interactions. In the antiparallel case, two main maxima occur and appear to correspond to divalent ion tactoids which have been previously reported. For the Cohen-Longley Mg2+ tactoid the best fit is obtained with a molecular overlap of 201 residues and an end overlap of 17-18 residues (based on a rational 287 peptide sequence). Secondary maxima correspond to other known tactoid forms. Binding of tropomyosin molecules to actin may involve hydrogen bonding to six serine residues which occur at approx. 40-residue intervals.

Binding Sites↗
PubMedDate not supplied

Block copolypeptides. 1. Synthesis and solid state conformational studies.

Triblock copolypeptides of gamma-benzyl L-glutamate (G) and L-leucine or L-valine of high molecular weight have been prepared. The solubilites and solution conformation were determined and compared with random copolymers of similar composition as well as the appropriate homopolypeptides. Characterization of the secondary structure in the solid state was undertaken as part of an investigation into the solid state properties of this new class of materials. Infrared and solid state measurements indicate that the G and L-leucine blocks assume an alpha-helical conformation and L-valine blocks a beta-sheet structure. Polarized infrared measurements showed the chain axis in oriented films to be parallel to the orientation direction. Further solid state characterization of the tertiary structure and mechanical properties of the block copolypeptides will be reported in succeeding papers.

Circular Dichroism↗