Investigations into the Role of Conformational Dynamics in Protein Function: Insights From Hydrogen/Deuterium Exchange-Mass Spectrometry

Deciphering protein structure and dynamics is a key prerequisite for understanding biological function. The current work aims to apply HDX-MS to improve the understanding of protein structure and dynamics for systems that remain challenging for other techniques. Following a general overview of the field (Chapter 1), Chapter 2 investigates the relationship between enzyme dynamics and catalysis. By conducting comparative HDX-MS measurements on rM1-PK during substrate turnover and in the resting state, catalytically active rM1-PK undergoes significant rigidification of the active site. However, virtually the same rigidification was seen upon exposing rM1-PK to substrate or product in the absence of turnover. These findings demonstrate that comparative experiments on enzyme dynamics by HDX-MS (and other bioanalytical techniques) should be interpreted with caution. In Chapter 3, HDX-MS is used to probe the intrinsically disordered protein Nrf2. HDX-MS is used to investigate the structure and dynamics of the full-length Nrf2 and its interaction with the Kelch domain. The data obtained demonstrate the highly-disordered nature of Nrf2. Its interaction with Kelch causes protection of the binding sites on Nrf2, while the rest of the protein becomes slightly more dynamic. This works highlights the limitations of using truncated protein constructs when investigating their structure and dynamic properties using biophysical techniques

Changes in Enzyme Structural Dynamics Studied by Hydrogen Exchange-Mass Spectrometry: Ligand Binding Effects or Catalytically Relevant Motions?

It is believed that enzyme catalysis is facilitated by conformational dynamics of the protein scaffold that surrounds the active site, yet the exact nature of catalytically relevant protein motions remains largely unknown. Hydrogen/deuterium exchange (HDX) mass spectrometry (MS) reports on backbone H-bond fluctuations. HDX/MS thus represents a promising avenue for probing the relationship between enzyme dynamics and catalysis. A seemingly straightforward strategy for such studies involves comparative measurements during substrate turnover and in the resting state. We examined the feasibility of this approach using rabbit muscle pyruvate kinase (rM1-PK) which catalyzes the conversion of phosphoenolpyruvate and Mg-ADP to pyruvate and Mg-ATP. HDX/MS revealed that catalytically active rM1-PK undergoes significant rigidification in the active site. This finding is counterintuitive, considering the purported correlation between dynamics and catalysis. Interestingly, virtually the same rigidification was seen upon exposing rM1-PK to substrates or products in the absence of turnover. These data imply that the active site dynamics during turnover are dominated by protein-ligand binding interactions. These interactions stabilize H-bonds in the vicinity of the active site, thereby masking subtle dynamic features that might be uniquely associated with catalysis. Our data uncover an inherent problem with side-by-side turnover/resting state measurements, i.e., the difficulty to design a suitable reference state against which the working enzyme can be compared. Comparative HDX/MS experiments on enzyme dynamics should therefore be interpreted with caution

An organizing framework for informal caregiver interventions: detailing caregiving activities and caregiver and care recipient outcomes to optimize evaluation efforts

Abstract Background Caregiver interventions may help improve the quality of informal care. Yet the lack of a systematic framework specifying the targets and outcomes of caregiver interventions hampers our ability to understand what has been studied, to evaluate existing programs, and to inform the design of future programs. Our goal was to develop an organizing framework detailing the components of the caregiving activities and the caregiver and care recipient outcomes that should be affected by an intervention. In so doing, we characterize what has been measured in the published literature to date and what should be measured in future studies to enable comparisons across interventions and across time. Methods Our data set comprises 121 reports of caregiver interventions conducted in the United States and published between 2000 and 2009. We extracted information on variables that have been examined as primary and secondary outcomes. These variables were grouped into categories, which then informed the organizing framework. We calculated the frequency with which the interventions examined each framework component to identify areas about which we have the most knowledge and under-studied areas that deserve attention in future research. Results The framework stipulates that caregiver interventions seek to change caregiving activities, which in turn affect caregiver and care recipient outcomes. The most frequently assessed variables have been caregiver psychological outcomes (especially depression and burden) and care recipient physical and health care use outcomes. Conclusions Based on the organizing framework, we make three key recommendations to guide interventions and inform research and policy. First, all intervention studies should assess quality and/or quantity of caregiving activities to help understand to what extent and how well the intervention worked. Second, intervention studies should assess a broad range of caregiver and care recipient outcomes, including considering whether expanding to economic status and health care use of the caregiver can be accommodated, to ease subsequent economic evaluations of caregiving. Third, intervention studies should measure a common set of outcomes to facilitate cross-time and cross-study comparisons of effectiveness

Depression and Missed Work among Informal Caregivers of Older Individuals with Dementia

Absenteeism, CES-D, Depression, Informal care, Missing work,

Tuberculosis: integrated studies for a complex disease 2050

Tuberculosis (TB) has been a disease for centuries with various challenges [1]. Like other places where challenges and opportunities come together, TB challenges were the inspiration for the scientific community to mobilize different groups for the purpose of interest. For example, with the emergence of drug resistance, there has been a huge volume of research on the discovery of new medicines and drug delivery methods and the repurposing of old drugs [2, 3]. Moreover, to enhance the capacity to detect TB cases, studies have sought diagnostics and biomarkers, with much hope recently expressed in the direction of point-of-care tests [4]. Despite all such efforts as being highlighted in 50 Chapters of this volume, we are still writing about TB and thinking about how to fight this old disease–implying that the problem of TB might be complex, so calling the need for an integrated science to deal with multiple dimensions in a simultaneous and effective manner. We are not the first one; there have been proposed integrated platform for TB research, integrated prevention services, integrated models for drug screening, integrated imaging protocol, integrated understanding of the disease pathogenesis, integrated control models, integrated mapping of the genome of the pathogen, etc. [5–12], to name some. These integrated jobs date back decades ago. So, a question arises: why is there a disease named TB yet? It might be due to the fact that this integration has happened to a scale that is not global, and so TB remains to be a problem, especially in resource-limited settings. Hope Tuberculosis: Integrated Studies for a Complex Disease helps to globalize the integrated science of TB.info:eu-repo/semantics/publishedVersio