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1.
Light Sci Appl ; 13(1): 24, 2024 Jan 22.
Article En | MEDLINE | ID: mdl-38253485

Lithium (Li) dendrite growth significantly deteriorates the performance and shortens the operation life of lithium metal batteries. Capturing the intricate dynamics of surface localized and rapid mass transport at the electrolyte-electrode interface of lithium metal is essential for the understanding of the dendrite growth process, and the evaluation of the solutions mitigating the dendrite growth issue. Here we demonstrate an approach based on an ultrasensitive tilted fiber Bragg grating (TFBG) sensor which is inserted close to the electrode surface in a working lithium metal battery, without disturbing its operation. Thanks to the superfine optical resonances of the TFBG, in situ and rapid monitoring of mass transport kinetics and lithium dendrite growth at the nanoscale interface of lithium anodes have been achieved. Reliable correlations between the performance of different natural/artificial solid electrolyte interphases (SEIs) and the time-resolved optical responses have been observed and quantified, enabling us to link the nanoscale ion and SEI behavior with the macroscopic battery performance. This new operando tool will provide additional capabilities for parametrization of the batteries' electrochemistry and help identify the optimal interphases of lithium metal batteries to enhance battery performance and its safety.

2.
J Agric Food Chem ; 71(49): 19288-19301, 2023 Dec 13.
Article En | MEDLINE | ID: mdl-38036943

3-Alkyl-2-methoxypyrazines (MPs) could be considered as off-flavor for red wine if the concentration exceeds a certain threshold. It is unknown whether the vine water status has an influence on MP metabolism in grape berries and, therefore, in wines. This study aimed to evaluate the effect of vine water status on MP content and on the expression level of VvOMTs; moreover, the exact functions of VvOMT2/3 were investigated. In this study, the grapevines were subjected over two years (2020 and 2021) to different levels of water constraints and the treatments were (i) light water constraint (LW); (ii) moderate water constraint (MW); and (iii) severe water constraint (SW) in comparison with well-irrigated vines used as control (CK). The results showed that six MPs, including ETMP, MEMP, MOMP, SBMP, IPMP, and IBMP, were negatively and significantly affected by water constraints. Meanwhile, the levels of VvOMT1, VvOMT2, VvOMT3, and VvOMT4 were 0.17-fold, 0.13-fold, 0.35-fold, and 0.75-fold, respectively, at 40 DAA or 60 DAA under MW treatment relative to CK in 2020. In 2021, the trend was similar to that in 2020. When VvOMT2 and VvOMT3 genes were transiently overexpressed in grape berries and callus, both their expression level and protein level were induced; in addition, IPMP, SBMP, and IBMP contents were significantly increased. Moreover, heterologous expression of VvOMT3 in tomato led to IPMP, SBMP, and IBMP accumulation, whereas VvOMT2 could only promote the accumulation of IPMP. Altogether, moderate water constraint not only improved the quality of "Marselan" grape berries but also reduced the MP content per berry. This study showed for the first time, according to our knowledge, the effect of vine water constraint on the metabolism of MPs by way of allowing the reduction of the precursors of this aromatic compound, which could be perceived as an off-flavor impacting negatively wine aromatic profiles with notes of asparagus and green pepper.


Vitis , Wine , Vitis/genetics , Vitis/metabolism , Fruit/genetics , Fruit/metabolism , Antiviral Agents/metabolism , Wine/analysis
3.
Nat Commun ; 14(1): 5251, 2023 Aug 29.
Article En | MEDLINE | ID: mdl-37640698

Operando monitoring of complex physical and chemical activities inside rechargeable lithium-ion batteries during thermal runaway is critical to understanding thermal runaway mechanisms and giving early warning of safety-related failure. However, most existing sensors cannot survive during such extremely hazardous thermal runaway processes (temperature up to 500 °C accompanied by fire and explosion). To address this, we develop a compact and multifunctional optical fiber sensor (12 mm in length and 125 µm in diameter) capable of insertion into commercial 18650 cells to continuously monitor internal temperature and pressure effects during cell thermal runaway. We observe a stable and reproducible correlation between the cell thermal runaway and the optical response. The sensor's signal shows two internal pressure peaks corresponding to safety venting and initiation of thermal runaway. Further analysis reveals that a scalable solution for predicting imminent thermal runaway is the detection of the abrupt turning range of the differential curves of cell temperature and pressure, which corresponds to an internal transformation between the cell reversible and irreversible reactions. By raising an alert even before safety venting, this new operando measurement tool can provide crucial capabilities in cell safety assessment and warning of thermal runaway.

4.
Chemosphere ; 333: 138834, 2023 Aug.
Article En | MEDLINE | ID: mdl-37142100

Natural organic matter (NOM) plays an important role in the iodine mobilization in the groundwater system. In this study, the groundwater and sediments from iodine affected aquifers in the Datong Basin were collected to perform chemistry analysis and molecular characteristics of NOM by Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR-MS). Total iodine concentrations in groundwater and sediments ranged from 1.97 to 926.1 µg/L and 0.001-2.86 µg/g, respectively. A positive correlation was observed between DOC/NOM and groundwater/sediment iodine. FT-ICR-MS results showed that the DOM in the high-iodine groundwater system is characterized by less aliphatic and more aromatic compounds with higher NOSC, indicating the features of more unsaturated larger molecule structures and more bioavailability. Aromatic compounds could be the main carriers of sediment iodine and were easily absorbed on amorphous iron oxides to form the NOM-Fe-I complex. More aliphatic compounds, especially those containing N/S, experienced a higher degree of biodegradation, which further mediated the reductive dissolution of amorphous iron oxides and the transformation of iodine species, thereby causing the release of iodine into groundwater. The findings of this study provide some new insights into the mechanisms of high-iodine groundwater.


Arsenic , Groundwater , Iodine , Water Pollutants, Chemical , Iodine/analysis , Water Pollutants, Chemical/analysis , Geologic Sediments/chemistry , Groundwater/chemistry , China , Iron/analysis , Oxides/analysis , Arsenic/analysis
5.
Environ Pollut ; 329: 121686, 2023 Jul 15.
Article En | MEDLINE | ID: mdl-37105462

Redox processes can induce arsenic (As) and iodine (I) transformation and thus change As and I co-occurrence, yet there is no evidence that Fe-C-S coupled redox processes have such an impact on the co-occurrence of As and I. To fill this gap, middle-deep groundwater from the Datong Basin were samples for the purpose of exploring how dissolved organic matter (DOM) reactivity affects As and I enrichment and how iron reduction and sulfate reduction processes influence As and I co-occurrence. We identified three DOM components: reduced and oxidized quinone compounds (C1 and C3) and a labile DOM from terrestrial inputs (C2). Two pathways of DOM processing take place in the aquifer, including the degradation of labile DOM to HCO3- and the transformation of oxidized quinone compounds to reduced quinone compounds. Electrons transfer drives the reduction of the terminal electron acceptors. The supply of electrons promotes the reduction of iron and sulfate by microbes, enhancing As and I co-enrichment in groundwater. Thus, the reduction processes of iron and sulfate triggered by the dual roles of DOM affect dissolved As and I co-enrichment. As and I biogeochemical cycling interacts with C, Fe, and S cycling. These results provide isotopic and fluorescence evidence that explains the co-occurrence of arsenic and iodine in middle-deep aquifers.


Arsenic , Groundwater , Iodine , Water Pollutants, Chemical , Arsenic/analysis , Water Pollutants, Chemical/analysis , Environmental Monitoring , Groundwater/chemistry , Iron/analysis , Dissolved Organic Matter , Quinones
6.
Foods ; 12(23)2023 Nov 21.
Article En | MEDLINE | ID: mdl-38231685

Malic acid is the predominant organic acid in grape berries, and its content is affected by abiotic factors such as temperature (fruit zone microclimate) and water (vine water status). The objectives of this study were to explore the potential mechanisms behind the effects of vine water status on the biosynthesis and degradation of berry malic acid and the potential downstream effects on berry metabolism. This study was conducted over two growing seasons in 2021 and 2022, comprising three watering regimes: no water stress (CK), light water stress (LWS), and moderate water stress (MWS). Compared to CK, a significantly higher level of malic acid was found in berries from the MWS treatment when the berry was still hard and green (E-L 33) in both years. However, water stress reduced the malic acid content at the ripe berry harvest (E-L 38) stage. The activities of NAD-malate dehydrogenase (NAD-MDH) and pyruvate kinase (PK) were enhanced by water stress. Except for the E-L 33 stage, the activity of phosphoenolpyruvate carboxylase (PEPC) was reduced by water stress. The highest phosphoenolpyruvate carboxykinase (PEPCK) activity was observed at the berry veraison (E-L 35) stage and coincided with the onset of a decrease in the malate content. Meanwhile, the expression of VvPEPCK was consistent with its enzyme activity. This study showed that water stress changed the content of some free amino acids (GABA, proline, leucine, aspartate, and glutamate), two of which (glutamate and GABA) are primary metabolites of the GABA pathway.

7.
Environ Sci Pollut Res Int ; 29(32): 49007-49028, 2022 Jul.
Article En | MEDLINE | ID: mdl-35212896

As an element relevant to human health, iodine is highly worthy of researchers' attention, especially the mechanism of iodine migration and enrichment in groundwater systems. A total of 43 groundwater, 1 seawater, 107 sediment, and 111 pore water samples from two boreholes (toward to Bohai Sea: BT, HH) were collected along a groundwater flow path at the North China Plain to investigate hydro-geochemical processes controlling groundwater iodine. High iodine groundwater (> 100 µg/L) was characterized by Na-Cl type, with high TDS values (827-2,400 mg/L) and high Cl (110-705 mg/L) and Br (416-1,180 µg/L) concentrations, which may be related to marine influence. Borehole BT and HH had pore water I concentration ranges of 1.4-132 µg/L and 3.6-830 µg/L, with high level that occurred near to coastline and corresponded to ancient transgression events. The results of sequential extraction of borehole sediments indicate that the fractions of sediment inorganic iodine mainly consisted of exchangeable, carbonate, and Fe-oxides associated fractions. Fe-oxides associated iodine was the main occurrence state in borehole BT far from the coastline, but high exchangeable iodine fractions (up to 92% of total extracted iodine) were observed in a high salinity borehole HH located near Bohai Bay, corresponding to the occurrence of high iodine pore water and groundwater. The analysis of iodine species indicates that iodide with strong migration ability dominated high iodine groundwater, pore water, and exchangeable sediment iodine, reflecting the occurrence of adsorption/desorption processes of iodine in groundwater system. High iodine groundwater and pore water exhibited iodine enrichment relative to Cl and Br, which suggests that iodine adsorbed on sediment desorbed under suitable pH and high solution ionic strength and subsequently released to pore water and aquifers. Inverse geochemical modeling stressed that ion exchange plays an important role in iodine enrichment of groundwater system.


Groundwater , Iodine , Water Pollutants, Chemical , China , Environmental Monitoring , Geologic Sediments/chemistry , Groundwater/chemistry , Humans , Iodides , Iodine/analysis , Oxides/analysis , Water/analysis , Water Pollutants, Chemical/analysis
8.
Updates Surg ; 74(2): 685-695, 2022 Apr.
Article En | MEDLINE | ID: mdl-33709243

Third space robotic and endoscopic cooperative surgery (TS-RECS) is a novel minimally invasive surgery for resecting gastric submucosal tumours (GSMTs), which could accomplish the completely oncological curability and maximal functional preservation. This study investigated the clinical outcomes and gastrointestinal function after TS-RECS versus laparoscopic wedge resection (LWR) for GSMTs. This was a single-centre retrospective study that included 130 patients with GSMTs who underwent LWR or TS-RECS from 2013 to 2019. To overcome selection biases, we performed propensity score matching (1:1) using seven covariates that could impact the group assignment and outcomes. Then, the clinical outcomes and gastrointestinal function in the LWR and TS-RECS groups were compared in a matched cohort. Among the 130 enrolled patients, 96 patients underwent LWR, and 34 underwent TS-RECS and were matched into 30 patients for each group. There was no significant difference in the operation time between the two groups (P = 0.543). However, the TS-RECS group had significantly less blood loss (20,5-100 vs 95,10-310 ml, P < 0.0001) and better postoperative recovery in terms of time to oral intake (2,2-4 vs 3,2-6 days, P < 0.0001) and postoperative hospital stay (5,4-10 vs 8.5,5-16 days, P < 0.0001) than the LWR group. The severity and frequency scores of postoperative gastrointestinal symptoms in the TS-RECS group were significantly lower than those in the LWR group. The median follow-up period was 24 months (10-60 months) in the LWR group and 18 months (10-27 months) in the TS-RECS group, and there was in total a single recurrence in the LWR group. TS-RECS appears to be a technically safe and effective surgery with preservation of gastrointestinal function for resection of GSMT resection.


Gastrointestinal Stromal Tumors , Laparoscopy , Robotic Surgical Procedures , Stomach Neoplasms , Gastrointestinal Stromal Tumors/surgery , Humans , Propensity Score , Retrospective Studies , Stomach Neoplasms/pathology , Treatment Outcome
9.
Sci Total Environ ; 745: 140922, 2020 Nov 25.
Article En | MEDLINE | ID: mdl-32736101

Long-term intake of groundwater with elevated iodine concentration can cause thyroid dysfunction in humans; however, little is known on the mechanisms controlling the fate of iodine in groundwater systems. In this study, the groundwater and aquifer sediment samples from the Datong basin, a geologic iodine-affected area, were collected to perform the batch incubation experiments to understand the release and enrichment of iodine in groundwater systems. The results showed that the groundwater from the deep confined aquifer had a total iodine concentration of 473 µg/L, higher than that of shallow groundwater, and iodide is the dominant species of iodine. The deep confined aquifer was characterized by the reducing conditions. Meanwhile, a higher ratio of Fe(II) to total Fe was observed in bulk deep aquifer sediments (59%) in comparison with that of shallow sediments (33%). The results of batch incubation experiments showed that during the reductive transformation of Fe minerals in shallow aquifer sediments, iodide concentration in solution was gradually increasing from 24.7 to 101.5 µg/L after 10 days. It suggests that the transformation of Fe minerals in aquifer sediments acts as a diver causing the release of iodine from sediment into groundwater, which was further supported by the features Fe K-edge EXAFS before and after the batch experiments. Moreover, the changes in iodine species from iodate or organic iodine into iodide during the release further promotes the release of sediment iodine, which was supported by the developed geochemical models. The prevalence of reducing condition in deep aquifer favors the enrichment of released iodide. This study provides new insights into the mechanisms of iodide enrichment observed in deep confined aquifer.

10.
Sci Total Environ ; 730: 138877, 2020 Aug 15.
Article En | MEDLINE | ID: mdl-32388365

Fluoride enrichment in groundwater at the North China Plain (NCP) is posing a potential health risk to human being. To better understand the enrichment mechanism of fluoride in the groundwater systems, the groundwater, sediments samples and pore water compacted from clayey sediments were collected to perform the chemistry analysis and geochemical inverse modeling. The results showed that fluoride concentration in groundwater from the NCP has a range of 0.38-7.35 mg/L, and 67.8% of groundwater samples have the fluoride concentration higher than 1.5 mg/L. High fluoride groundwater was mainly distributed in the central plain and coastal area of the NCP, and characterized by the Na-HCO3 or Na-Cl type water, lower Ca and higher TDS concentrations. Along groundwater flow-path from the mountainous to coastal areas, several hydrogeochemical processes control the mobilization and enrichment of fluoride in groundwater, including cation exchange between Ca and Na on the surface of clay minerals, precipitation/dissolution of carbonates, dissolution of fluorite, marine transgressions, and release of pore water trapped in clayey sediments caused by land subsidence. The fluoride concentrations in the pore water compacted from the sediments ranged from 2.92 to 4.48 mg/L. At the central plain and coastal area, the wide occurrence of land subsidence resulted from the groundwater over-exploration leads to the release of pore water rich in fluoride into surrounding aquifers, thereby elevating the concentration of groundwater fluoride. The resulted groundwater environment with high salinity and some newly-introduced ions, such as Mg, promote the dissolution of fluorite, which was under-saturated in the groundwater samples from the NCP, further enhancing the fluoride enrichment in the groundwater at the coastal area. The findings of this study will provide new insights on the generation of high fluoride groundwater.

12.
Sci Total Environ ; 686: 50-62, 2019 Oct 10.
Article En | MEDLINE | ID: mdl-31176823

Groundwater iodine has direct importance for human dietary iodine intake in areas where drinking water is of groundwater origin. However, little is known about enrichment and mobilization mechanisms of groundwater iodine in the North China Plain (NCP). Geochemistry, inorganic/organic carbon isotope and biomarker of groundwater and sediment samples were studied to reveal the effects of depositional environment and organic matter (OM) degradation on the generation of high iodine groundwater (>100 µg/L) in NCP. Results showed that groundwater iodine had a range of 7.2-800 µg/L and was increasing with increase in HCO3 concentration and decrease in groundwater δ13CDIC value, indicating the potential effects of microbial activity on the elevation of groundwater iodine. Sediments iodine ranged from 0.03 to 2.54 µg/g and higher contents occurred under the oxidizing depositional environment (higher Pr/Ph ratios). Biomarker analysis indicated that the marine iodine-rich OM is considered as the main source of groundwater iodine, which is prone to be released into groundwater by the microbial degradation under the reducing conditions. The hypothesis was evidenced by the 13Corg, 13CDIC and 3-D excitation emission matrices of groundwater. These results suggest that carbon-related biogeochemical cycling and redox condition are important in the enrichment and mobilization of iodine in groundwater system.


Environmental Monitoring , Groundwater/chemistry , Iodine/analysis , Water Pollutants, Chemical/analysis , China , Geologic Sediments/chemistry
13.
Water Res ; 159: 480-489, 2019 Aug 01.
Article En | MEDLINE | ID: mdl-31128472

To understand the effects of large-scale sediment compaction on iodine enrichment in the groundwater system of the North China Plain (NCP), hydrogeochemical and isotope (2H, 18O and 87Sr/86Sr) geochemical features of groundwater, seawater and pore water of the deep aquifer sediments were characterized. Groundwater iodine concentration ranged from 5.8 to 1110 µg/L and approximately 80% of groundwater samples have iodine concentration more than 100 µg/L. High iodine groundwater (>100 µg/L) is mainly distributed in the Bohai bay area where serious land subsidence occurs. The sediments deposited during several events of marine transgression are considered as the main source of groundwater iodine. The pore solution compacted from the clayey sediments has a iodine concentration up to 830 µg/L, indicating that marine source iodine was stored in the clayey layers. The hydrogen and oxygen isotope signatures of groundwater show that the groundwater from NCP is mainly recharged by precipitation and the pore water from sediment compaction due to intense land subsidence. The Cl/Br molar ratio and 87Sr/86Sr signatures of groundwater and sediment pore water further suggest the effects of mixing with compaction-released pore solution on the hydrochemical evolution of high iodine groundwater. Based on groundwater δ2H, Cl concentration and 87Sr/86Sr, the results of two end-members mixing model calculation indicate that the compaction-released pore solution contributes approximately 49.1-68.9% iodine to high iodine groundwater, and the iodine from compaction-released pore solution ranges between 407 and 572 µg/L. The results of this study therefore suggest that the compaction of clayey sediments can be a major hydrogeological process controlling the genesis of high iodine groundwater in deep aquifers at NCP.


Groundwater , Iodine , Water Pollutants, Chemical , China , Environmental Monitoring
14.
Cell Discov ; 4: 27, 2018.
Article En | MEDLINE | ID: mdl-29872539

Acid-sensing ion channels (ASICs) are neuronal voltage-independent Na+ channels that are activated by extracellular acidification. ASICs play essential roles in a wide range of physiological processes, including sodium homeostasis, synaptic plasticity, neurodegeneration, and sensory transduction. Mambalgins, a family of three-finger toxins isolated from black mamba venom, specifically inhibit ASICs to exert strong analgesic effects in vivo, thus are thought to have potential therapeutic values against pain. However, the interaction and inhibition mechanism of mambalgin on ASICs remains elusive. Here, we report a cryo-electron microscopy (cryo-EM) structure of chicken ASIC1a (cASIC1a) in complex with mambalgin-1 toxin at 5.4 Å resolution. Our structure provides the first experimental evidence that mambalgin-1 interacts directly with the extracellular thumb domain of cASIC1a, rather than inserting into the acid-sensing pocket, as previously reported. Binding of mambalgin-1 leads to relocation of the thumb domain that could disrupt the acidic pocket of cASIC1a, illustrating an unusual inhibition mechanism of toxins on ASIC channels through an allosteric effect. These findings establish a structural basis for the toxicity of the mambalgins, and provide crucial insights for the development of new optimized inhibitors of ASICs.

15.
Medicine (Baltimore) ; 97(8): e9786, 2018 Feb.
Article En | MEDLINE | ID: mdl-29465560

BACKGROUND: This study aimed to compare olanzapine and haloperidol efficacies in the treatment of acute psychiatric symptoms due to amphetamine-type stimulants (ATSs). METHODS: The Zelen II design method was used; 124 patients with acute mental disorders due to amphetamine were randomly divided into olanzapine group (n = 63) and haloperidol group (n = 61). Then, a 4-week open-label medical therapy was performed. Clinical Global Impression Scale Item 2 was employed to evaluate the onset time; meanwhile, Brief Psychiatric Rating Scale (BPRS) was used at baseline and at posttreatment weeks 1, 2, and 4. Moreover, adverse reactions during the treatment were recorded. RESULTS: Onset time in the olanzapine group was significantly earlier than in the haloperidol group; BPRS scores in the olanzapine group were significantly lower than haloperidol group values at 1 and 2 weeks of treatment. The overall effective rates had no statistically significant difference. CONCLUSION: Short-term olanzapine and haloperidol treatments had equivalent efficacies in the treatment of acute symptoms of mental disorders due to ATSs; however, olanzapine administration resulted in relatively earlier disease onset, with less adverse reactions.


Amphetamine-Related Disorders/drug therapy , Antipsychotic Agents/administration & dosage , Benzodiazepines/administration & dosage , Haloperidol/administration & dosage , Mental Disorders/drug therapy , Adult , Amphetamine/adverse effects , Amphetamine-Related Disorders/psychology , Brief Psychiatric Rating Scale , Central Nervous System Stimulants/adverse effects , Female , Humans , Male , Mental Disorders/chemically induced , Olanzapine , Research Design , Treatment Outcome
16.
Sci Total Environ ; 598: 239-248, 2017 Nov 15.
Article En | MEDLINE | ID: mdl-28441602

To better understand the enrichment of fluoride and iodine in groundwater at North China Plain (NCP), speciation analysis and geochemical modeling were conducted to identify the key hydrochemical processes controlling their mobilization in groundwater system. Groundwater fluoride and iodine concentrations ranged from 0.18 to 5.59mg/L and from 1.51 to 1106µg/L, respectively, and approximately 63% and 32.3% of groundwater fluoride and iodine were higher than the guidelines for drinking water (1.5mg/L and 150µg/L). High fluoride concentration (>1.5mg/L) can be detected in groundwater from the flow-through and discharge areas of NCP, and high iodine groundwater (>150µg/L) is mainly scattered in the coastal area. Na-HCO3/Cl type water resulted from water-rock interaction and seawater intrusion favors fluoride and iodine enrichment in groundwater. Speciation analysis results indicate that (1) fluoride complexes in groundwater are dominated by free fluoride, the negative charge of which favors fluoride enrichment in groundwater under basic conditions, and (2) iodide, iodate and organic iodine co-occur in groundwater at NCP with iodide as the dominant species. The geochemical modeling results indicate that groundwater fluoride is mainly associated with the saturation states of fluorite and calcite, as well as the adsorption equilibrium onto goethite and gibbsite, including the competitive adsorption between fluoride and carbonate. Groundwater iodine is mainly controlled by redox potential and pH condition of groundwater system. Reducing condition favors the mobilization and enrichment of groundwater iodide, which has the highest mobility among iodine species. Under reducing condition, reductive dissolution of iron (oxy)hydroxides is a potential geochemical process responsible for iodine release from sediment into groundwater. Under (sub)oxidizing condition, as groundwater pH over the 'point of zero charge' of iron (oxy)hydroxides, the lowering adsorption capacity of groundwater iodide/iodate on minerals leads to the release of sediment iodine into groundwater.

17.
Proc Natl Acad Sci U S A ; 113(10): 2642-7, 2016 Mar 08.
Article En | MEDLINE | ID: mdl-26929360

The eukaryotic proteasome mediates degradation of polyubiquitinated proteins. Here we report the single-particle cryoelectron microscopy (cryo-EM) structures of the endogenous 26S proteasome from Saccharomyces cerevisiae at 4.6- to 6.3-Šresolution. The fine features of the cryo-EM maps allow modeling of 18 subunits in the regulatory particle and 28 in the core particle. The proteasome exhibits two distinct conformational states, designated M1 and M2, which correspond to those reported previously for the proteasome purified in the presence of ATP-γS and ATP, respectively. These conformations also correspond to those of the proteasome in the presence and absence of exogenous substrate. Structure-guided biochemical analysis reveals enhanced deubiquitylating enzyme activity of Rpn11 upon assembly of the lid. Our structures serve as a molecular basis for mechanistic understanding of proteasome function.


Proteasome Endopeptidase Complex/chemistry , Protein Conformation , Saccharomyces cerevisiae Proteins/chemistry , Saccharomyces cerevisiae/enzymology , Cryoelectron Microscopy/methods , Crystallography, X-Ray , Models, Molecular , Proteasome Endopeptidase Complex/metabolism , Proteasome Endopeptidase Complex/ultrastructure , Proteolysis , Saccharomyces cerevisiae Proteins/metabolism , Saccharomyces cerevisiae Proteins/ultrastructure , Substrate Specificity
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