Off-campus University of Richmond users: To download campus access theses, please use the following link to log in to our proxy server with your university username and password.
Date of Award
Restricted Thesis: Campus only access
Bachelor of Science
Dr. Richard Topham
Octopus dofleini and Octopus vulgaris hemocyanin contain structurally important disulfide bonds which maintain the oxygen-binding ability of the molecule. The molecules may structurally be broken down into domains, each of which contains a dicopper oxygen-binding site. Proteolytic cleavage followed by high performance chromotagraphy was used to isolate specifically the g-domain of these hemocyanins. To see if disulfide bonds were necessary to maintain oxygen-binding capacity within a specific domain as well as the whole subunits of the hemocyanin, the bonds were broken with reducing agents. The oxygen-binding was measured by the 348nm detectable color produced by the copper/oxygen charge-transfer band. Disulfide bonds were not only found to be important in maintaining oxygen-binding capacity of a single domain within the subunit, but also in maintaining the tertiary structure of the whole subunit. These disulfide bonds were able to reform once the reducing agent was removed, fully restoring the oxygen-binding and the tertiary structure. A number of factors allosterically affect the oxygen affinity of the hemocyanins, notebly pH, cations and anions. The effect of pH on the loss of the oxygen capacity upon disruption of the disulfide bonds was explored with the hemocyanin of Octopus vulgaris. A DTT treatment at 7.0, 8.0, 8.5, and 9.0 pH values showed that the stability of the molecule was pH dependent. These studies, coupled with previous experiments of the importance of disulfide bonds of arthropod hemocyanin, suggest that disulfide bond cleavage maybe an excellent chemical probe for studying the structure-function relationships of hemocyanins in general.
Westcott, Amy M., "Importance of disulfide bonds in the structural maintenance of the oxygen-binding sites of Octopus Hemocyanin" (1998). Honors Theses. 467.