Characterization and Effect of Metal Ions on the Formation of the \u3cem\u3eThermus thermophilus\u3c/em\u3e Sco Mixed Disulfide Intermediate

The Sco protein from Thermus thermophilus has previously been shown to perform a disulfide bond reduction in the CuA protein from T. thermophilus, which is a soluble protein engineered from subunit II of cytochrome ba 3 oxidase that lacks the transmembrane helix. The native cysteines on TtSco and TtCuA were mutated to serine residues to probe the reactivities of the individual cysteines. Conjugation of TNB to the remaining cysteine in TtCuA and subsequent release upon incubation with the complementary TtSco protein demonstrated the formation of the mixed disulfide intermediate. The cysteine of TtSco that attacks the disulfide bond in the target TtCuA protein was determined to be TtSco Cysteine 49. This cysteine is likely more reactive than Cysteine 53 due to a higher degree of solvent exposure. Removal of the metal binding histidine, His 139, does not change MDI formation. However, altering the arginine adjacent to the reactive cysteine in Sco (Arginine 48) does alter the formation of the MDI. Binding of Cu2+ or Cu+ to TtSco prior to reaction with TtCuA was found to preclude formation of the mixed disulfide intermediate. These results shed light on a mechanism of disulfide bond reduction by the TtSco protein and may point to a possible role of metal binding in regulating the activity. Importance: The function of Sco is at the center of many studies. The disulfide bond reduction in CuA by Sco is investigated herein and the effect of metal ions on the ability to reduce and form a mixed disulfide intermediate are also probed

Evaluation of environmental and nutritional changes in a home food environment intervention for weight loss

There is a pressing need to improve standard behavioral weight loss (BWL) programs to improve both short-term and long-term weight loss outcomes. One limitation of current BWL programs is that they rely heavily on participants’ own self-control to make and sustain major changes to their diet and overall energy intake. However, the reliability of willpower alone to maintain weight loss has been called into question; over time, when weight loss slows and motivation drops, adherence to the implementation of core BWL skills and principles may drop and lead to weight regain. Increased structure and targeted skills designed to shift the burden away from self-control could help improve dietary intake and weight loss outcomes in BWL. The current study aimed to investigate changes in the home food environment and dietary intake across three weight loss conditions: standard behavior therapy, behavior therapy plus meal replacement provisions, and behavior therapy supplemented with nutritional and food environment counseling (Nutritrol). Across all three conditions, results showed that participants were able to make positive quantitative (i.e., reductions in overall energy intake) and qualitative (e.g., decrease in percentage of energy intake coming from fat) changes over the course of the intervention, although the sustainability of these changes in the follow-up period was mixed. Over time, Nutritrol showed a meaningful advantage over the other conditions regarding the percentage of intake that came from carbohydrates and fats, and the overall amount of fiber that was consumed. Contrary to our hypotheses, no other differences were detected in dietary quality, quantity of energy intake, or obesogenic nature of the home food environment between conditions. Possible explanations for these lack of significant findings, including measurement tool limitations or insufficient treatment doses, are discussed.M.S., Psychology -- Drexel University, 201