This dissertation project represents an investigation of the regulation of glycolysis during contractile activity in the phasic adductor muscle of the bay scallop Argopecten irradians concentricus. Changes in intracellular pH during the course of 200 electrically stimulated contractions were monitored using ('31)P-NMR. There was an initial increase (from 7.06 to 7.15) followed by a gradual decrease in intracellular pH. Intracellular pH dropped to 6.94 after 200 contractions. The pattern of changes in intracellular pH was closely correlated with the pattern of proton yield from metabolic energy transformations. Changes in the concentrations of glycolytic intermediates during the course of contractile activity were measured in order to identify the potential regulatory sites of glycolysis. The estimated mass action ratios at resting conditions and after contraction, as well as the maximum activities of glycolytic enzymes, indicated that phosphorylase and phosphofructokinase were catalyzing non-equilibrium reactions in the muscle. Regulation of the terminal dehydrogenase in glycolysis, namely octopine dehydrogenase, was investigated by studying the kinetic properties of the purified enzyme. It was concluded that pyruvate was the decisive factor in activating octopine dehydrogenase. Activities of both phosphorylase and phosphofructokinase increased during muscle contraction. Phosphofructokinase appeared to be the main rate limiting enzyme in the later stages of contraction. Activation of the first rate limiting enzyme in glycolysis, namely phosphorylase, was mainly by the conversion of the inactive enzyme form (phosphorylase b) to the active form (phosphorylase a). The percentage of phosphorylase a rose from 21% to 81% of total phosphorylase after 160 electrically stimulated contractions. Activation of phosphofructokinase resulted mainly from increase in / positive modulators such as AMP and fructose-2,6-P. The initial increases in intracellular pH may also result in considerable increase of the activity of phosphofructokinase. / Source: Dissertation Abstracts International, Volume: 46-12, Section: B, page: 4147. / Thesis (Ph.D.)--The Florida State University, 1985.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_75707 |
| Contributors | CHIH, CHING-PING., Florida State University |
| Source Sets | Florida State University |
| Detected Language | English |
| Type | Text |
| Format | 166 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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