ABSTRACT
C-Nitroso compounds (RNO, R = alkyl and aryl) are byproducts of drug metabolism and bind to heme proteins, and their heme-RNO adducts are isoelectronic to ferrous nitroxyl (NO-/HNO) complexes. Importantly, heme-HNO compounds are key intermediates in the reduction of NO to N2O and nitrite to ammonium in the nitrogen cycle. Ferrous heme-RNO complexes act as stable analogs of these species, potentially allowing for the investigation of the vibrational and electronic properties of unstable heme-HNO intermediates. In this paper, a series of six-coordinate ferrous heme-RNO complexes (where R = iPr and Ph) were prepared using the TPP2- and 3,5-Me-BAFP2- co-ligands, and tetrahydrofuran, pyridine, and 1-methylimidazole as the axial ligands (bound trans to RNO). These complexes were characterized using different spectroscopic methods and X-ray crystallography. The complex [Fe(TPP)(THF)(iPrNO)] was further utilized for nuclear resonance vibrational spectroscopy (NRVS), allowing for the detailed assignment of the Fe-N(R)O vibrations of a heme-RNO complex for the first time. The vibrational properties of these species were then correlated with those of their HNO analogs, using DFT calculations. Our studies support previous findings that RNO ligands in ferrous heme complexes do not elicit a significant trans effect. In addition, the complexes are air-stable, and do not show any reactivity of their RNO ligands towards NO. So although ferrous heme-RNO complexes are suitable structural and electronic models for their HNO analogs, they are unsuitable to model the reactivity of heme-HNO complexes. We further investigated the reaction of our heme-RNO complexes with different Lewis acids. Here, [Fe(TPP)(THF)(iPrNO)] was found to be unreactive towards Lewis acids. In contrast, [Fe(3,5-Me-BAFP)(iPrNO)2] is reactive towards all of the Lewis acids investigated here, but in most cases the iron center is simply oxidized, resulting in the loss of the iPrNO ligand. In the case of the Lewis acid B2(pin)2, the reduced product [Fe(3,5-Me-BAFP)(iPrNH2)(iPrNO)] was identified by X-ray crystallography.
ABSTRACT
BACKGROUND: The Making Every Contact Count (MECC) programme provides training and materials to support public-facing workers to encourage health-promoting behaviour change by using the day-to-day interactions between organisations and individuals. This project aimed to analyse MECC implementation through a comparative analysis of implementation stage, strategies used for implementation and enablers/barriers of the implementation process within a region in England-the North East and North Cumbria (NENC). METHODS: A mixed-methods process evaluation was conducted applying normalisation process theory and theoretical domains framework. MECC programme documents were reviewed and mapped against specific criteria (eg, implementation strategies). An online mapping survey was conducted to establish current implementation/delivery of MECC within NENC settings (eg, local government, healthcare and voluntary community sector). Qualitative research, using individual interviews and group discussions, was conducted to establish further understanding of MECC implementation. RESULTS: Our findings were informed by reviewing documents (n=5), surveying participants (n=34), interviews (n=18) and group discussions (n=48). Overall, the implementation of MECC within the region was at an early stage, with training mostly delivered between, rather than within, organisations. Qualitative findings highlighted factors that influence stakeholders to implement MECC (eg, organisational goals that were facilitated by MECC implementation, including the prevention agenda), supported resources that facilitate the implementation of MECC (eg, logic models) and enabling factors that promote MECC sustainability across the region (eg, buy-in from leadership and management). CONCLUSIONS: The NENC MECC programme is built around regional leadership that supports the implementation process. This process evaluation identified key influences of MECC implementation across the region. We discuss evidence-based recommendation for policy and practice that can be taken forward to develop targeted strategies to support future MECC implementation. For example, a co-ordinated infrastructure and strategy is needed to combat delivery and implementation issues identified.
Subject(s)
Health Promotion , Humans , England , Health Promotion/methods , Qualitative Research , Program Evaluation , Surveys and QuestionnairesABSTRACT
BACKGROUND: Cervical cancer incidence and mortality is higher in lower income populations. Non-attendance for colposcopy following cervical screening is higher in deprived areas and younger patients. Diagnostic delays reduce the benefits of screening, increasing risk of pre-cancerous cells being undetected or treated later. We aimed to better understand drivers of colposcopy non-attendance and pilot a targeted intervention. Women and people with a cervix (referred to as patients in this paper) access colposcopy services. METHODS: For the service improvement audit, we collected qualitative data from Jan 24 to April 22, 2022, via telephone calls and interviews. The sample included patients who cancelled or did not attend their appointment and patients who attended their appointment. Interviews explored attendance barriers and enablers. Data were analysed thematically and reported, aligning with Consolidated Criteria for reporting Qualitative Studies' principles. The analysis informed development of a pilot intervention, implemented from Aug 8 to Oct 6, 2022, for all scheduled appointments. Patients were contacted by telephone pre-appointment as both a reminder and opportunity to identify and address attendance barriers. Barrier-specific pathways were developed to support attendance (eg, transport assistance). We compared descriptive non-attendance rates during the intervention period and pre-intervention. Audit permission was granted by Northumbria Clinical Audit Team and Caldicott approval obtained. FINDINGS: Data were collected from 20 of the 36 patients who did not attend between Jan 24, and April 22, 2022. Further data were gathered from 88 patients cancelling appointments and four colposcopy attendees. During the audit, ethnicity and gender identity were not routinely collected. Themes identified were administrative, forgetting, anxiety, work, childcare, and transport. During the pilot, 383 (65%) of all 595 patients with an appointment were successfully contacted. The overall non-attendance in 2022 pre-telephone intervention was 10% (195 of 1736 appointments). During the intervention, non-attendance was 8% (45 of 539 appointments). Non-attendance during the intervention was 12% (10 of 87 appointments) for patients aged 25-39 years in the 20% most deprived areas was, compared with 20% (64 of 319 appointments) before the intervention. INTERPRETATION: Identifying and addressing attendance barriers might improve non-attendance, particularly in younger and more deprived populations. This offers the prospect of improving the effectiveness of screening programmes alongside reducing inequalities in health-care access. The findings of this small-scale study are limited to NHS trust colposcopy service in the northeast of England, thus further formalised research is necessary. FUNDING: None.
Subject(s)
Colposcopy , Uterine Cervical Neoplasms , Humans , Male , Female , Pregnancy , Early Detection of Cancer/methods , Uterine Cervical Neoplasms/diagnosis , Uterine Cervical Neoplasms/prevention & control , Gender Identity , Anxiety , Patient ComplianceABSTRACT
Bacterial NO Reductase (NorBC or cNOR) is a membrane-bound enzyme found in denitrifying bacteria that catalyzes the two-electron reduction of NO to N2O and water. The mechanism by which NorBC operates is highly debated, due to the fact that this enzyme is difficult to work with, and no intermediates of the NO reduction reaction could have been identified so far. The unique active site of NorBC consists of a heme b3/non-heme FeB diiron center. Synthetic model complexes provide the opportunity to obtain insight into possible mechanistic alternatives for this enzyme. In this paper, we present three new synthetic model systems for NorBC, consisting of a tetraphenylporphyrin-derivative clicked to modified BMPA-based ligands (BMPA = bis(methylpyridyl)amine) that model the non-heme site in the enzyme. These complexes have been characterized by EPR, IR and UV-Vis spectroscopy. The reactivity with NO was then investigated, and it was found that the complex with the BMPA-carboxylate ligand as the non-heme component has a very low affinity for NO at the non-heme iron site. If the carboxylate functional group is replaced with a phenolate or pyridine group, reactivity is restored and formation of a diiron dinitrosyl complex was observed. Upon one-electron reduction of the nitrosylated complexes, following the semireduced pathway for NO reduction, formation of dinitrosyl iron complexes (DNICs) was observed in all three cases, but no N2O could be detected.
Subject(s)
Click Chemistry , Nitric Oxide , Nitric Oxide/metabolism , Iron/chemistry , Bacteria/metabolism , Heme/chemistry , Oxidation-ReductionABSTRACT
Background: 'Making Every Contact Count' (MECC) is a public health strategy supporting public-facing workers to use opportunities during routine contacts to enable health behaviour change. A mental health hospital in the North East of England is currently implementing a programme to embed MECC across the hospital supporting weight management ('A Weight Off Your Mind'). Bespoke MECC training has been developed to improve staff confidence in discussing physical activity, healthy eating, and related behaviour change with service users. This article describes the protocol for a pragmatic formative process evaluation to inform the implementation plan for MECC and facilitate successful implementation of the bespoke MECC training at scale. Methods/Design: An 18-month, mixed method pragmatic formative process evaluation, including qualitative research, surveys, document review and stakeholder engagement. This project is conducted within a mental health inpatient setting in the North East of England. Programme documents will be reviewed, mapped against MECC national guidelines, Behaviour Change Techniques (BCTs) and intervention functions within the Behaviour Change Wheel. A cross-sectional survey (n = 365) and qualitative semi-structured interviews (n = 30) will be conducted with healthcare practitioners delivering MECC to assess capability, opportunity and motivation. Data collection and fidelity procedures will be examined, including design, training and delivery dimensions of fidelity. Interviews with service users (n = 20) will also be conducted. Discussion: Anticipated outcomes include developing recommendations to overcome barriers to delivery of and access to MECC, including whether to either support the use of the existing MECC protocol or tailor the MECC training programme. The findings are anticipated to improve fidelity of MECC training within mental health inpatient settings as well as provide evidence for MECC training at a national level. We also expect findings to influence strategic plans, policy, and practice specific to MECC and inform best practice in implementing wider brief intervention programmes.
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BACKGROUND: Multiple complex needs (MCN) describe a population experiencing a combination of homelessness, substance use, offending and/or mental ill-health. Using peer researchers, this study aimed to explore the perspectives of individuals with lived experience of MCN with regards to (i) issues leading to MCN and (ii) key intervention opportunities. METHODS: As part of a health needs assessment in Gateshead (North East England), trained peer researchers interviewed 27 adults (aged ≥18 years) with experience of MCN, identified using purposive sampling methods. Peer researchers designed a topic guide for interviews which were audio recorded and thematically analyzed. RESULTS: Interviewees reported adverse childhood experiences leading to MCN including abuse, bereavement, parental imprisonment, family break-up and inadequate support. Mental ill-health, substance use, poverty, early experiences of unstable housing and acute homelessness were identified as major precedents for adulthood experiences of MCN. Between 16 and 20 years, access to housing, social and mental health support was perceived as having the potential to prevent circumstances worsening. Individuals perceived removing barriers to mental health, housing and welfare and financial supports could help. CONCLUSIONS: This study highlights the perceived role austerity, adverse childhood events and current service provision have in current and future experiences of MCN. Individuals expressed a need for future interventions and support to be judgement free and provided by workers who are educated about MCN and related adversity. Involving peer researchers and individuals with experience of MCN in future research and service provision could ensure appropriate measures and supports are put in place.
Subject(s)
Ill-Housed Persons , Life Change Events , Adolescent , Adult , Child , Housing , Humans , Mental Health , Needs AssessmentABSTRACT
Nitric oxide (NO) is an important signaling molecule that is involved in a wide range of physiological and pathological events in biology. Metal coordination chemistry, especially with iron, is at the heart of many biological transformations involving NO. A series of heme proteins, nitric oxide synthases (NOS), soluble guanylate cyclase (sGC), and nitrophorins, are responsible for the biosynthesis, sensing, and transport of NO. Alternatively, NO can be generated from nitrite by heme- and copper-containing nitrite reductases (NIRs). The NO-bearing small molecules such as nitrosothiols and dinitrosyl iron complexes (DNICs) can serve as an alternative vehicle for NO storage and transport. Once NO is formed, the rich reaction chemistry of NO leads to a wide variety of biological activities including reduction of NO by heme or non-heme iron-containing NO reductases and protein post-translational modifications by DNICs. Much of our understanding of the reactivity of metal sites in biology with NO and the mechanisms of these transformations has come from the elucidation of the geometric and electronic structures and chemical reactivity of synthetic model systems, in synergy with biochemical and biophysical studies on the relevant proteins themselves. This review focuses on recent advancements from studies on proteins and model complexes that not only have improved our understanding of the biological roles of NO but also have provided foundations for biomedical research and for bio-inspired catalyst design in energy science.
Subject(s)
Hemeproteins , Nitric Oxide , Electronics , Heme/chemistry , Iron/chemistry , Nitric Oxide/chemistry , Nitrogen Oxides/chemistryABSTRACT
Coupled dinuclear copper oxygen cores (Cu2 O2 ) featured in type III copper proteins (hemocyanin, tyrosinase, catechol oxidase) are vital for O2 transport and substrate oxidation in many organisms. µ-1,2-cis peroxido dicopper cores (C P) have been proposed as key structures in the early stages of O2 binding in these proteins; their reversible isomerization to other Cu2 O2 cores are directly relevant to enzyme function. Despite the relevance of such species to type III copper proteins and the broader interest in the properties and reactivity of bimetallic C P cores in biological and synthetic systems, the properties and reactivity of C P Cu2 O2 species remain largely unexplored. Herein, we report the reversible interconversion of µ-1,2-trans peroxido (T P) and C P dicopper cores. CaII mediates this process by reversible binding at the Cu2 O2 core, highlighting the unique capability for metal-ion binding events to stabilize novel reactive fragments and control O2 activation in biomimetic systems.
Subject(s)
Calcium/chemistry , Copper/chemistry , Binding Sites , Ions/chemistry , Molecular StructureABSTRACT
OBJECTIVE: To explore the perceived reasons underlying high mortality rates among people with multiple and complex needs. DESIGN: Qualitative study using peer research. SETTING: North East of England. PARTICIPANTS: Three focus group discussions were held involving (1) people with lived experience of multiple and complex needs (n=5); (2) front-line staff from health, social care and voluntary organisations that support multiple and complex needs groups (n=7); and (3) managers and commissioners of these organisations (n=9). RESULTS: Findings from this study provide valuable perspectives of people with multiple complex needs and those that provide them with support on what may be perceived factors underlying premature mortality. Mental ill health and substance misuse (often co-occurring dual diagnosis) were perceived as influencing premature mortality among multiple and complex needs groups. Perceptions of opportunities to identify people at risk included critical life events (eg, bereavement, relationship breakdown) and transitions (eg, release from prison, completion of drug treatment). Early prevention, particularly supporting young people experiencing adverse childhood experiences, was also highlighted as a priority. CONCLUSION: High mortality in multiple and complex needs groups may be reduced by addressing dual diagnosis, providing more support at critical life events and investing in early prevention efforts. Future interventions could take into consideration the intricate nature of multiple and complex needs and improve service access and navigation.
Subject(s)
Mental Health , Social Support , Adolescent , Diagnosis, Dual (Psychiatry) , England/epidemiology , Humans , Qualitative ResearchABSTRACT
Rev-Erbß is a nuclear receptor that couples circadian rhythm, metabolism, and inflammation. Heme binding to the protein modulates its function as a repressor, its stability, its ability to bind other proteins, and its activity in gas sensing. Rev-Erbß binds Fe3+-heme more tightly than Fe2+-heme, suggesting its activities may be regulated by the heme redox state. Yet, this critical role of heme redox chemistry in defining the protein's resting state and function is unknown. We demonstrate by electrochemical and whole-cell electron paramagnetic resonance experiments that Rev-Erbß exists in the Fe3+ form within the cell allowing the protein to be heme replete even at low concentrations of labile heme in the nucleus. However, being in the Fe3+ redox state contradicts Rev-Erb's known function as a gas sensor, which dogma asserts must be Fe2+ This paper explains why the resting Fe3+ state is congruent both with heme binding and cellular gas sensing. We show that the binding of CO/NO elicits a striking increase in the redox potential of the Fe3+/Fe2+ couple, characteristic of an EC mechanism in which the unfavorable Electrochemical reduction of heme is coupled to the highly favorable Chemical reaction of gas binding, making the reduction spontaneous. Thus, Fe3+-Rev-Erbß remains heme-loaded, crucial for its repressor activity, and undergoes reduction when diatomic gases are present. This work has broad implications for proteins in which ligand-triggered redox changes cause conformational changes influencing its function or interprotein interactions (e.g., between NCoR1 and Rev-Erbß). This study opens up the possibility of CO/NO-mediated regulation of the circadian rhythm through redox changes in Rev-Erbß.
Subject(s)
Carbon Monoxide/metabolism , Electrons , Heme/metabolism , Iron/metabolism , Nitric Oxide/metabolism , Receptors, Cytoplasmic and Nuclear/metabolism , Repressor Proteins/metabolism , Binding Sites , Biological Transport , Carbon Monoxide/chemistry , Circadian Rhythm/physiology , Electron Spin Resonance Spectroscopy , Electron Transport , Escherichia coli/genetics , Escherichia coli/metabolism , Gene Expression , Heme/chemistry , Humans , Iron/chemistry , Models, Biological , Models, Molecular , Nitric Oxide/chemistry , Oxidation-Reduction , Protein Binding , Protein Conformation, alpha-Helical , Protein Conformation, beta-Strand , Protein Interaction Domains and Motifs , Receptors, Cytoplasmic and Nuclear/chemistry , Receptors, Cytoplasmic and Nuclear/genetics , Recombinant Fusion Proteins/chemistry , Recombinant Fusion Proteins/genetics , Recombinant Fusion Proteins/metabolism , Repressor Proteins/chemistry , Repressor Proteins/geneticsABSTRACT
Manganese porphyrins are used as catalysts in the oxidation of olefins and nonactivated hydrocarbons. Key to these reactions are high-valent Mn-(di)oxo species, for which [Mn(Porph)(X)] serve as precursors. To elucidate their properties, it is crucial to understand the interaction of the Mn center with the porphyrin ligand. Our study focuses on simple high-spin [MnIII(TPP)X] (X = F, Cl, I, Br) complexes with emphasis on the spectroscopic properties of [MnIII(TPP)Cl], using variable-temperature variable-field magnetic circular dichroism spectroscopy and time-dependent density functional theory to help with band assignments. The optical properties of [MnIII(TPP)Cl] are complicated and unusual, with a Soret band showing a high-intensity feature at 21050 cm-1 and a broad band that spans 23200-31700 cm-1. The 15000-18500 cm-1 region shows the Cl(px/y) â dπ (CT(Cl,π)), Q band, and overlap-forbidden Cl(px/y)_dπ â dx2-y2 transitions that gain intensity from the strongly allowed π â π*(0) transition. The 20000-21000 cm-1 region displays the prominent pseudo A-type signal of the Soret band. The strongly absorbing features at 22500-28000 cm-1 exhibit A1u⟨79⟩/A2u⟨81⟩ â dπ, CT(Cl,π/σ), and symmetry-forbidden CT character, mixed with the π â π*(0) transition. The strong dx2-y2_B1g⟨80⟩ orbital interaction drives the ground-state MO mixing. Importantly, the splitting of the Soret band is explained by strong mixing of the porphyrin A2u(π)⟨81⟩ and the Cl(pz)_dz2 orbitals. Through this direct orbital pathway, the π â π*(0) transition acquires intrinsic metal-d â porphyrin CT character, where the π â π*(0) intensity is then transferred into the high-energy CT region of the optical spectrum. The heavier halide complexes support this conclusion and show enhanced orbital mixing and drastically increased Soret band splittings, where the 21050 cm-1 band shifts to lower energy and the high-energy features in the 23200-31700 cm-1 range increase further in intensity, compared to the chloro complex.
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Cupredoxins are copper-dependent electron-transfer proteins that can be categorized as blue, purple, green, and red depending on the spectroscopic properties of the Cu(II) bound forms. Interestingly, despite significantly different first coordination spheres and nuclearity, all cupredoxins share a common Greek Key ß-sheet fold. We have previously reported the design of a red copper protein within a completely distinct three-helical bundle protein, α3DChC2. (1) While this design demonstrated that a ß-barrel fold was not requisite to recapitulate the properties of a native cupredoxin center, the parent peptide α3D was not sufficiently stable to allow further study through additional mutations. Here we present the design of an elongated protein GRANDα3D (GRα3D) with Δ Gu = -11.4 kcal/mol compared to the original design's -5.1 kcal/mol. Diffraction quality crystals were grown of GRα3D (a first for an α3D peptide) and solved to a resolution of 1.34 Å. Examination of this structure suggested that Glu41 might interact with the Cu in our previously reported red copper protein. The previous bis(histidine)(cysteine) site (GRα3DChC2) was designed into this new scaffold and a series of variant constructs were made to explore this hypothesis. Mutation studies around Glu41 not only prove the proposed interaction, but also enabled tuning of the constructs' hyperfine coupling constant from 160 to 127 × 10-4 cm-1. X-ray absorption spectroscopy analysis is consistent with these hyperfine coupling differences being the result of variant 4p mixing related to coordination geometry changes. These studies not only prove that an Glu41-Cu interaction leads to the α3DChC2 construct's red copper protein like spectral properties, but also exemplify the exact control one can have in a de novo construct to tune the properties of an electron-transfer Cu site.