This study aimed to test the differences of weight-related self-stigma and mental health conditions between overweight (OW) and non-OW children in Hong Kong. The correlations between weight-related self-stigma and mental health conditions were also investigated. Children aged 8 to 12 years (n = 367; 198 boys) completed questionnaires on weight-related self-stigma (Weight Bias Internalization Scale [WBIS] and Weight Self-Stigma Questionnaire [WSSQ]) and mental health conditions (Brief Symptom Rating Scale-5 [BSRS-5]). Compared with non-OW children (n = 241; 143 boys), OW children (n = 114; 55 boys) had higher weight-related self-stigma in the WBIS (26.49 ± 8.68 vs. 21.58 ± 7.54; p < 0.001) and WSSQ scores (26.36 ± 8.98 vs. 21.91 ± 8.71; p < 0.001). No significant difference was found between OW and non-OW children in mental health conditions as reflected by the BSRS-5 score (4.29 ± 4.35 vs. 4.44 ± 4.16; p = 0.761). BSRS-5 was significantly associated with the WBIS. OW children tended to have a higher level of self-stigma; those having a higher level of weight-related self-stigma presented with more mental health problems.
Zinc finger proteins that bind Zn(II) using a Cys2His2 coordination motif within a ββα protein fold are the most abundant DNA binding transcription factor domains in eukaryotic systems. These classic zinc fingers are typically unfolded in the apo state and spontaneously fold into their functional ββα folds upon incorporation of Zn(II). These metal-induced protein folding events obscure the free energy cost of protein folding by coupling the protein folding and metal-ion binding thermodynamics. Herein, we determine the formation constant of a Cys2His2/ββα zinc finger domain, the C-terminal finger of the Wilms’ tumor suppressor protein (WT1-4), for the purposes of determining its free energy cost of protein folding. Measurements of individual conditional dissociation constants, Kd values, at pH values from 5 to 9 were determined using fluorescence spectroscopy by direct or competition titration. Potentiometric titrations of apo-WT1-4 followed by NMR spectroscopy provided the intrinsic pKa values of the Cys2His2 residues, and corresponding potentiometric titrations of Zn(II)–WT1-4 followed by fluorescence spectroscopy yielded the effective pKaeff values of the Cys2His2 ligands bound to Zn(II). The Kd, pKa, and pKaeff values were combined in a minimal, complete equilibrium model to yield the pH-independent formation constant value for Zn(II)–WT1-4, KfML value of 7.5 × 1012 M–1, with a limiting Kd value of 133 fM. This shows that Zn(II) binding to the Cys2His2 site in WT1-4 provides at least −17.6 kcal/mol in driving force to fold the protein scaffold. A comparison of the conditional dissociation constants of Zn(II)–WT1-4 to those from the model peptide Zn(II)–GGG–Cys2His2 over the pH range 5.0 to 9.0 and a comparison of their pH-independent KfML values demonstrates that the free energy cost of protein folding in WT1-4 is less than +2.1 kcal/mol. These results validate our GGG model system for determining the cost of protein folding in natural zinc finger proteins and support the conclusion that the cost of protein folding in most zinc finger proteins is ≤+4.2 kcal/mol, a value that pales in comparison to the free energy contribution of Zn(II) binding, −17.6 kcal/mol.
Evidence linking amyloid beta (Aβ) cellular uptake and toxicity has burgeoned, and mechanisms underlying this association are subjects of active research. Two major, interconnected questions are whether Aβ uptake is aggregation-dependent and whether it is sequence-specific. We recently reported that the neuronal uptake of Aβ depends significantly on peptide chirality, suggesting that the process is predominantly receptor-mediated. Over the past decade, the cellular prion protein (PrPC) has emerged as an important mediator of Aβ-induced toxicity and of neuronal Aβ internalization. Here, we report that the soluble, nonfibrillizing Aβ (1–30) peptide recapitulates full-length Aβ stereoselective cellular uptake, allowing us to decouple aggregation from cellular, receptor-mediated internalization. Moreover, we found that Aβ (1–30) uptake is also dependent on PrPC expression. NMR-based molecular-level characterization identified the docking site on PrPC that underlies the stereoselective binding of Aβ (1–30). Our findings therefore identify a specific sequence within Aβ that is responsible for the recognition of the peptide by PrPC, as well as PrPC-dependent cellular uptake. Further uptake stereodifferentiation in PrPC-free cells points toward additional receptor-mediated interactions as likely contributors for Aβ cellular internalization. Taken together, our results highlight the potential of targeting cellular surface receptors to inhibit Aβ cellular uptake as an alternative route for future therapeutic development for Alzheimer’s disease.
Methionine (Met) oxidation is an important biological redox node, with hundreds if not thousands of protein targets. The process yields methionine oxide (MetO). It renders the sulfur chiral, producing two distinct, diastereomerically related products. Despite the biological significance of Met oxidation, a reliable protocol to separate the resultant MetO diastereomers is currently lacking. This hampers our ability to make peptides and proteins that contain stereochemically defined MetO to then study their structural and functional properties. We have developed a facile method that uses supercritical CO2 chromatography and allows obtaining both diastereomers in purities exceeding 99 %. 1H NMR spectra were correlated with X‐ray structural information. The stereochemical interconversion barrier at sulfur was calculated as 45.2 kcal mol−1, highlighting the remarkable stereochemical stability of MetO sulfur chirality. Our protocol should open the road to synthesis and study of a wide variety of stereochemically defined MetO‐containing proteins and peptides.
Methionine sulfoxide chirality is emerging as an important signaling node in redox biology, regulating cellular processes as pivotal as actin polymerization. Research is hampered by lack of methods to obtain pure methionine sulfoxide diastereomers. The present contribution provides a scalable process, which, using supercritical CO2, allows rapid access to both diastereomers in purities of 99.9 % and should open the road the systematic chemical biology studies of methionine redox processes. More information can be found in the Communication by J. A. Raskatov et al. on page 4467.
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