Registered users receive a variety of benefits including the ability to customize email alerts, create favorite journals list, and save searches.
Please note that a BioOne web account does not automatically grant access to full-text content. An institutional or society member subscription is required to view non-Open Access content.
Contact firstname.lastname@example.org with any questions.
The reversible, mitochondrial membrane-associated transhydrogenase from the midgut of Manduca sexta (L.) (Lepidoptera: Sphingidae) catalyzes hydride-ion transfer between NADP(H) and NAD(H). The effects of ecdysone and 20-hydroxyecdysone were evaluated and compared to both the NADH-NADP and NADPH-NAD transhydrogenations. In the direction of NADPH-formation, the developmentally significant transhydrogenations occur as non-energy- or energy-linked reactions. The energy-linked activity couples with either electron transport-dependent NADH or succinate utilization, or ATP hydrolysis by Mg -dependent ATPase. Upon the addition of ecdysone alone, all energy-linked reactions in the direction of NADPH formation exhibited a notable increase in activity level over the control reaction. The addition of 20-hydroxyecdysone yielded no significant increase in the activity of any of the transhydrogenations. Synergistic addition of both ecdysone and 20-hydroxyecdysone resulted in no significant effect on transhydrogenase activity. The results of this study make evident a relationship between the presence of ecdysone and 20-hydroxyecdysone on the overall activity of M. sexta midgut mitochondrial transhydrogenations. The potential mediation of the energy-linked mitochondrial transhydrogenations involved with NADPH synthesis through the developmental relationship of ecdysone and 20-hydroxyecdysone is considered.