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The C 60 fullerene, renowned for its soccer ball-like high-symmetry configuration, has attracted extensive interest. As research on C 60 progresses, the synthesis of diverse C 60 derivatives and the exploration of embedding varying numbers of atoms within the carbon cage, ranging from singular atoms to entire molecules, have emerged. This trend has prompted investigations into potential high-symmetry structures formed by incorporating main group or transition metal elements. This study presents a detailed analysis of a three-layer Ag@Mg 12 @Ag 20 structure, featuring a Mg 12 icosahedron enclosed within an Ag 20 dodecahedron with a singular Ag atom at its core. Employing density-functional theory, the structure underwent comprehensive scrutiny, including energy minimization resulting in the adoption of a S 6 symmetry, and subsequent evaluation of stability via vibrational frequency analysis and molecular dynamics simulations. The electronic structures and bonding characteristics of this three-layer Ag@Mg 12 @Ag 20 architecture were explored through electron density analysis, density of states, and adaptive natural density partitioning analysis. Considering structural stability, the proposed three-layer Ag@Mg 12 @Ag 20 structure exhibits promise as a novel constituent in the construction of other nano-materials., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

This study investigates the relative perceptual distinction of the [n] vs [l] contrast in different vowel contexts ([_a] vs [_i]) and tonal contexts (high-initial such as HH, HL, vs low-initial such as LL, LH). The results of two speeded AX discrimination experiments indicated that a [n-l] contrast is perceptually more distinct in the [_a] context and with a high-initial tone. The results are consistent with the typology of the [n] vs [l] contrast across Chinese dialects, which is more frequently observed in the [_a] context and with a high-initial tone, supporting a connection between phonological typology and perceptual distinctiveness., (© 2024 Acoustical Society of America.)

Solution NMR spectroscopy of large protein systems is hampered by rapid signal decay, so most multidimensional studies focus on long-lived 1 H- 13 C magnetization in methyl groups and/or backbone amide 1 H- 15 N magnetization in an otherwise perdeuterated environment. Herein we demonstrate that it is possible to biosynthetically incorporate additional 1 H- 12 C groups that possess long-lived magnetization using cost-effective partially deuterated or unlabeled amino acid precursors added to Escherichia coli growth media. This approach is applied to the outer membrane enzyme PagP in membrane-mimetic dodecylphosphocholine micelles. We were able to obtain chemical shift assignments for a majority of side chain 1 H positions in PagP using nuclear Overhauser enhancements (NOEs) to connect them to previously assigned backbone 1 H- 15 N groups and newly assigned 1 H- 13 C methyl groups. Side chain methyl-to-aromatic NOEs were particularly important for confirming that the amphipathic α-helix of PagP packs against its eight-stranded β-barrel, as indicated by previous X-ray crystal structures. Interestingly, aromatic NOEs suggest that some aromatic residues in PagP that are buried in the membrane bilayer are highly mobile in the micellar environment, like Phe138 and Phe159. In contrast, Tyr87 in the middle of the bilayer is quite rigid, held in place by a hydrogen bonded network extending to the surface that resembles a classic catalytic triad: Tyr87-His67-Asp61. This hydrogen bonded arrangement of residues is not known to have any catalytic activity, but we postulate that its role is to immobilize Tyr87 to facilitate packing of the amphipathic α-helix against the β-barrel., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Peter Hwang reports financial support was provided by NSERC., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

The Stone-Wales defect is a well-known and significant defective structure in carbon materials, impacting their mechanical, chemical, and electronic properties. Recently, a novel metal-carbon nanomaterial named Volleyballene was discovered, characterized by a C-C bond bridging two carbon pentagons. Using first-principles calculations, a stable Stone-Wales-defective counterpart of Volleyballene, exhibiting T h symmetry, has been proposed by rotating the C-C bond by 90°. Although its binding energy per atom is slightly higher than that of Volleyballene (Δ E b = 0.009 eV/atom), implying marginally lower structural stability, it can maintain its bond structure until the effective temperature reaches about 1500 K, indicating greater thermodynamic stability. Additionally, its highest vibration frequency is 1346.2 cm -1 , indicating a strong chemical bond strength. A theoretical analysis of the Sc 20 C 60 + Sc 20 C 60 binary systems highlights that the stable building block may be applied in potential nanoassemblies.

In this study, we investigated Bartonella infection and its genetic diversity in rodents in Beitun, Xinjiang Uygur Autonomous Region, China. Small mammals were captured using snap traps at four sampling sites in 2018. Spleen and liver tissues were collected and cultured to isolate Bartonella strains. Whole-genome sequencing was performed on the strains identified as Bartonella by gltA gene PCR, and the average nucleotide identity (ANI) of the genomes was calculated by using FastANI v1.33. Phylogenetic trees were constructed for the samples positive for Bartonella spp. by the gltA PCR assay based on 1,290-bp gltA genes, 2,903-bp rpoB genes, and core-genome single nucleotide polymorphisms (SNPs). Among 66 rodents, 11 were positive for Bartonella , with an infection rate of 16.67%. The rodent infection rates in different tissues (χ 2 = 2.133; P = 0.242), species (χ 2 = 9.631; P = 0.141), and habitats (χ 2 = 4.309; P = 0.312) did not show statistical differences. Bartonella spp. isolated from the rodents were phylogenetically divided into six clades (two different Bartonella species were detected in two rodents). By comparing phylogenetic trees based on gltA genes, rpoB genes, and SNPs, we found that the topological structures of several evolutionary trees are different. However, the Bartonella strains isolated in this study were clustered into six clusters in different phylogenetic trees. Broad distributions and high genetic diversity of Bartonella strains were observed among rodents in Beitun, Xinjiang. IMPORTANCE Rodent-borne Bartonella species have been associated with zoonotic diseases. Bartonella species such as Bartonella elizabethae, Bartonella grahamii, and Bartonella tribocorum can cause disease in humans. Humans can be infected by blood-sucking arthropods through the scratches and bites of an infected reservoir host or via contact with infectious rodents. Xinjiang is one of the provinces with the most abundant species of Bartonella in China, but there are few reports about the prevalence of Bartonella in the Beitun area. This research aims to investigate the occurrence and prevalence of Bartonella infection in rodents at these sampling sites and provide a basis for the prevention and control of rodent Bartonella species in Beitun and the surrounding areas of Xinjiang.

Small molecule cardiac troponin activators could potentially enhance cardiac muscle contraction in the treatment of systolic heart failure. We designed a small molecule, RPI-194, to bind cardiac/slow skeletal muscle troponin (Cardiac muscle and slow skeletal muscle share a common isoform of the troponin C subunit.) Using solution NMR and stopped flow fluorescence spectroscopy, we determined that RPI-194 binds to cardiac troponin with a dissociation constant K D of 6-24 μM, stabilizing the activated complex between troponin C and the switch region of troponin I. The interaction between RPI-194 and troponin C is weak (K D 311 μM) in the absence of the switch region. RPI-194 acts as a calcium sensitizer, shifting the pCa 50 of isometric contraction from 6.28 to 6.99 in mouse slow skeletal muscle fibers and from 5.68 to 5.96 in skinned cardiac trabeculae at 100 μM concentration. There is also some cross-reactivity with fast skeletal muscle fibers (pCa 50 increases from 6.27 to 6.52). In the slack test performed on the same skinned skeletal muscle fibers, RPI-194 slowed the velocity of unloaded shortening at saturating calcium concentrations, suggesting that it slows the rate of actin-myosin cross-bridge cycling under these conditions. However, RPI-194 had no effect on the ATPase activity of purified actin-myosin. In isolated unloaded mouse cardiomyocytes, RPI-194 markedly decreased the velocity and amplitude of contractions. In contrast, cardiac function was preserved in mouse isolated perfused working hearts. In summary, the novel troponin activator RPI-194 acts as a calcium sensitizer in all striated muscle types. Surprisingly, it also slows the velocity of unloaded contraction, but the cause and significance of this is uncertain at this time. RPI-194 represents a new class of non-specific troponin activator that could potentially be used either to enhance cardiac muscle contractility in the setting of systolic heart failure or to enhance skeletal muscle contraction in neuromuscular disorders., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Mahmud, Tikunova, Belevych, Wagg, Zhabyeyev, Liu, Rasicci, Yengo, Oudit, Lopaschuk, Reiser, Davis and Hwang.)

Subjective cognitive decline (SCD), a self-reported worsening in cognition concurrent with normal performance on standardized neuropsychological tests, has gained much attention due to its high risks in the development of mild cognitive impairments or Alzheimer's disease. The existing cross-sectional diffusion tensor imaging (DTI) studies in SCD have shown extremely controversial findings. Furthermore, all of these studies investigated diffusion properties within the voxel, such as fractional anisotropy, mean diffusivity, or axial diffusivity (DA). However, it remains unclear whether individuals with SCD demonstrate alterations of diffusion profile between voxels and their neighbors, as indexed by local diffusion homogeneity (LDH). We selected 30 healthy controls (HCs) and 23 SCD subjects to acquire their whole-brain DTI. Diffusion images were compared using the tract-based spatial statistics method. Diffusion indices with significant between-group tract clusters were extracted from each individual for further region-of-interest (ROI)-based comparisons. Our results showed that subjects with SCD demonstrated reduced LDH in the left superior frontal gyrus (SFG) and DA in the right anterior cingulate cortex compared with the HC group. In contrast, the SCD group showed higher LDH values in the left lingual gyrus (LG) compared with the HC group. Notably, LDH in the left SFG was significantly and negatively correlated with LDH in the left LG. In conclusion, white matter (WM) integrity in the left SFG, right ACC, and left LG is altered in SCD, suggesting that individuals with SCD exhibit detectable changes in WM tracts before they demonstrate objective cognitive deficits., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Chao, Liu, Wang and Cheng.)

Cardiac troponin (cTn) is made up of three subunits, cTnC, cTnI, and cTnT. The regulatory N-terminal domain of cTnC (cNTnC) controls cardiac muscle contraction in a calcium-dependent manner. We show that calcium-saturated cNTnC can adopt two different orientations, with the "active" orientation consistent with the 2020 cryo-EM structure of the activated cardiac thin filament by Yamada et al. Using solution NMR 15 N R 2 relaxation analysis, we demonstrate that the two domains of cTnC tumble independently (average R 2 10 s -1 ), being connected by a flexible linker. However, upon addition of cTnI 1-77 , the complex tumbles as a rigid unit (R 2 30 s -1 ). cTnI phosphomimetic mutants S22D/S23D, S41D/S43D and dilated cardiomyopathy- (DCM-)associated mutations cTnI K35Q, cTnC D75Y, and cTnC G159D destabilize the active orientation of cNTnC, with intermediate 15 N R 2 rates (R 2 17-23 s -1 ). The active orientation of cNTnC is stabilized by the flexible tails of cTnI, cTnI 1-37 and cTnI 135-209 . Surprisingly, when cTnC is incorporated into complexes lacking these tails (cTnC-cTnI 38-134 , cTnC-cTnT 223-288 , or cTnC-cTnI 38-134 -cTnT 223-288 ), the cNTnC domain is still immobilized, revealing a new interaction between cNTnC and the IT-arm that stabilizes a "dormant" orientation. We propose that the calcium sensitivity of the cardiac troponin complex is regulated by an equilibrium between active and dormant orientations, which can be shifted through post-translational modifications or DCM-associated mutations., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

The hydrogen evolution reaction is a key half reaction for water electrolysis and is of great significance. Pt-based nanomaterials are promising candidates for HER electrocatalysts. However, the high price of platinum and poor durability impede their practical applications. Herein, a new CoMo-bimetallic hybrid zeolite imidazolate framework is employed to load Pt nanoparticles in a highly dispersed manner as a precursor to synthesize an efficient pH-universal HER electrocatalyst (PtCoMo@NC), which displays overpotentials of 26, 51, and 66 mV at a current density of 10 mA cm -2 in acidic, basic, and neutral media, respectively. The strong synergistic effect of highly dispersed multi-type catalytic species, including cobalt, molybdenum carbide, and platinum (4.7%) promotes the catalytic activity in the HER process. Meanwhile, the aggregation of Pt nanoparticles is greatly restrained by the carbon matrix so that a brilliant long-time durability of 12 hours and a negligible current decrease in the LSV curve after 10 000 CV cycles are achieved.

Background: Cardiac troponin I (cTnI) has two flexible tails that control the cardiac cycle. The C-terminal tail, cTnI 135-209 , binds actin to shut off cardiac muscle contraction, whereas the competing calcium-dependent binding of the switch region, cTnI 146-158 , by cardiac troponin C (cTnC) triggers contraction. The N-terminal tail, cTnI 1-37 , regulates the calcium affinity of cTnC. cTnI is known to be susceptible to proteolytic cleavage by matrix metalloproteinase-2 (MMP-2) and calpain, two intracellular proteases implicated in ischemia-reperfusion injury., Methods: Soluble fragments of cTnI containing its N- and C-terminal tails, cTnI 1-77 and cTnI 135-209 , were highly expressed and purified from E. coli. We performed in vitro proteolysis studies of both constructs using liquid chromatography-mass spectrometry and solution NMR studies of the C-terminal tail., Results: cTnI 135-209 is intrinsically disordered, though it contains three regions with helical propensity (including the switch region) that acquire more structure upon actin binding. We identified three precise MMP-2 cleavage sites at cTnI P17-I18, A156-L157, and G199-M200. In contrast, calpain-2 has numerous cleavage sites throughout Y25-T30 and A152-A160. The critical cTnI switch region is targeted by both proteases., Conclusions: Both N-terminal and C-terminal tails of cTnI are susceptible to cleavage by MMP-2 and calpain-2. Binding to cTnC or actin confers some protection to proteolysis, which can be understood in terms of their interactions as probed by NMR studies., General Significance: cTnI is an important marker of intracellular proteolysis in cardiomyocytes, given its many protease-specific cut sites, high natural abundance, indispensable functional role, and clinical use as gold standard biomarker of myocardial injury., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The compound MCI-154 was previously shown to increase the calcium sensitivity of cardiac muscle contraction. Using solution NMR spectroscopy, we demonstrate that MCI-154 interacts with the calcium-sensing subunit of the cardiac troponin complex, cardiac troponin C (cTnC). Surprisingly, however, it binds only to the structural C-terminal domain of cTnC (cCTnC), and not to the regulatory N-terminal domain (cNTnC) that determines the calcium sensitivity of cardiac muscle. Physiologically, cTnC is always bound to cardiac troponin I (cTnI), so we examined its interaction with MCI-154 in the presence of two soluble constructs, cTnI 1-77 and cTnI 135-209 , which contain all of the segments of cTnI known to interact with cTnC. Neither the cTnC-cTnI 1-77 complex nor the cTnC-cTnI 135-209 complex binds to MCI-154. Since residues 39-60 of cTnI are known to bind tightly to the cCTnC domain to form a structured core that is invariant throughout the cardiac cycle, we conclude that MCI-154 does not bind to cTnC when it is part of the intact cardiac troponin complex. Thus, MCI-154 likely exerts its calcium sensitizing effect by interacting with a target other than cardiac troponin.

Perdeuteration with selective 1 H, 13 C-enrichment of methyl groups has enabled solution NMR studies of large (>30 kDa) protein systems. However, we propose that for all non-methyl positions, only magnetization originating from 1 H- 12 C groups is sufficiently long-lived, and it can be transferred via through-space NOEs to slowly relaxing 1 H- 15 N or 1 H- 13 C methyl groups to achieve multidimensional solution NMR. We demonstrate stereoselective 1 H, 12 C-labeling by adding relatively inexpensive unlabeled carbon sources to Escherichia coli growth media in D 2 O. Using our model system, a mutant WW domain from human Pin1, we compare deuteration patterns in 19 amino acids (all except cysteine). Protein grown using glucose as the sole carbon source had high levels of protonation in aromatic rings and the H β positions of serine and tryptophan. In contrast, using our FROMP media (fumarate, rhamnose, oxalate, malonate, pyruvate), stereoselective protonation of H β2 with deuteration at H α and H β3 was achieved in Asp, Asn, Lys, and Met residues. In solution NMR, stereospecific chemical shift assignments for H β are typically obtained in conjunction with χ 1 dihedral angle determinations using 3-bond J-coupling ( 3 J N-Hβ , 3 J CO-Hβ , 3 J Hα-Hβ ) experiments. However, due to motional averaging, the assumption of a pure rotameric state can yield incorrect χ 1 dihedral angles with incorrect stereospecific assignments. This was the case for three residues in the Pin1 WW domain (Lys28, Met30, and Asn44). Thus, stereoselective 1 H, 12 C-labeling will be useful not only for NMR studies of large protein systems, but also for determining side chain rotamers and dynamics in any protein system.

Many proteins contain intrinsically disordered regions that are highly solvent-exposed and susceptible to post-translational modifications. Studying these protein segments is critical to understanding their physiologic regulation, but proteolytic degradation can make them difficult to express and purify. We have designed a new protein expression vector that fuses the target protein to the N-terminus of the integral membrane protein, PagP. The two proteins are connected by a short linker containing the sequence SRHW, previously shown to be optimal for nickel ion-catalyzed cleavage. The methodology is demonstrated for an intrinsically disordered segment of cardiac troponin I. cTnI[135-209]-SRHW-PagP-His6 fusion protein was overexpressed in Escherichia coli, accumulating in insoluble inclusion bodies. The protein was solubilized, purified using nickel affinity chromatography, and then cleaved with 0.5mM NiSO4 at pH 9.0 and 45 °C, all in 6M guanidine-HCl. Nickel ion-catalyzed peptide bond hydrolysis is an effective chemical cleavage technique under denaturing conditions that preclude the use of proteases. Moreover, nickel-catalyzed cleavage is more specific than the most commonly used agent, cyanogen bromide, which cleaves C-terminal to methionine residues. We were able to produce 15 mg of purified cTnI[135-209] from 1L of M9 minimal media using this protocol. The methodology is more generally applicable to the production of intrinsically disordered protein segments., (Copyright © 2015 Elsevier Inc. All rights reserved.)