Thesis (M.S.) in Animal Sciences--University of Maine, 2007. / Includes vita. Includes bibliographical references (leaves 65-71).

Thesis (Ph. D.)--University of Rhode Island, 2003. / Typescript. Includes bibliographical references (leaves 179-196).

Thesis (M.Sc.)--College of William and Mary. / Vita. Includes bibliographical references. Also available via the World Wide Web.

Thesis (M.S.) in Marine Biology--University of Maine, 2007. / Includes vita. Includes bibliographical references (leaves 58-65).

Thesis (M.S.) in Animal Sciences--University of Maine, 2008. / Includes vita. Includes bibliographical references (leaves 37-46).

Thesis (Ph.D.) in Oceanography--University of Maine, 2004. / Includes vita. Includes bibliographical references (leaves 128-135).

Thesis (M.Sc.)--Memorial University of Newfoundland, 2000. / Restricted until November 2001. Includes bibliographical references.

Thesis (Ph. D.)--Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1984. / Includes bibliographical references (p. 433-457).

Polyphenoloxidases (EC 1.10.3.1) (PPO) were extracted from the skin layer between the muscle and exoskeleton, of lobster (Homarus americanus) by the successive steps of (NH$ sb4) sb2$SO$ sb4$ fractionation, ion-exchange chromatography and isoelectric focusing. The lobster 'PPO-fraction' recovered by the 40-80% (NH$ sb4) sb2$SO$ sb4$ fractionation step was found to exist in the inactive precursor form which required trypsin for activation and was inhibited by polyvinyl pyrrolidone (PVP). A comparative study of the lobster 'PPO-fraction' and the commercial tyrosinase from mushroom (EC 1.14.18.1) indicated that the two enzymes were similar with respect to substrate specificity, response to pH and selected inhibitors (cysteine, EDTA and PABA). However, both enzymes differed from one another in terms of their thermal and pH stabilities. Their catalytic efficiencies indicated that tyrosinase was better suited to catalyze oxidation of DOPA than lobster 'PPO-fraction'. Also, the activity of both enzymes were enhanced by copper. / Further purification of the 'PPO-fraction' by ion-exchange chromatography and preparative isoelectric focusing with a Rotofor unit yielded three isozymes designated PPO 1, PPO 11 and PPO 111. These isozymes had pI values of 3.89, 4.26 and 4.54 and molecular weights of 32,180, 35,480 and 39,300 respectively. The isozymes were similar with respect to their pH and temperature activity profiles but differed from one another (especially PPO 1 versus PPOs 11 and 111) in terms of their pH and thermal stabilities. They also exhibited varying degrees of differences in their catalytic efficiencies. All three isozymes were inhibited by PABA, EDTA and cysteine, with PABA being a competitive inhibitor, and EDTA or cysteine a noncompetitive inhibitor. Lower concentrations of ascorbate and mercaptoethanol had no effect on the isozymes. The free amino acid analysis suggested that melanosis might originate from the skin of the lobster.

A collagenolytic enzyme fraction was isolated from the hepatopancreas of the lobster (Homarus americanus) and semi-purified by the successive steps of acetone precipitation, ammonium sulfate fractionation, ion exchange chromatography on Mono Q column, followed by gel filtration on a Superdex 75 column or by preparative isoelectric focusing using a Rotofor cell. / Semi-purified collagenase fractions from the lobster hepatopancreas was electrophoresed in polyacrylamide gels both in the presence or absence of SDS, and shown to have molecular weights ranging from 15,000-66,000. The enzymatically active peak 1 fraction from the isoelectric focusing step in the Rotofor cell migrated as a single band in 12% polyacrylamide gel with few light protein bands. / The pH-activity data indicated that the collagenase fraction had two pH optima for the hydrolysis of native collagen, one at pH 4 and the other between pH 7-8. / The temperature-activity data for the hydrolysis of native collagen indicated the lobster enzyme exhibited two temperature optima--a minor one at 25$ sp circ$C and a more pronounced one between 40$ sp circ$C and 50$ sp circ$C.