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1.
J Mol Model ; 30(5): 156, 2024 May 02.
Article in English | MEDLINE | ID: mdl-38693294

ABSTRACT

CONTEXT: Due to their excellent biocompatibility and degradability, cellulose/spider silk protein composites hold a significant value in biomedical applications such as tissue engineering, drug delivery, and medical dressings. The interfacial interactions between cellulose and spider silk protein affect the properties of the composite. Therefore, it is important to understand the interfacial interactions between spider silk protein and cellulose to guide the design and optimization of composites. The study of the adsorption of protein on specific surfaces of cellulose crystal can be very complex using experimental methods. Molecular dynamics simulations allow the exploration of various physical and chemical changes at the atomic level of the material and enable an atomic description of the interactions between cellulose crystal planes and spider silk protein. In this study, molecular dynamics simulations were employed to investigate the interfacial interactions between spider silk protein (NTD) and cellulose surfaces. Findings of RMSD, RMSF, and secondary structure showed that the structure of NTD proteins remained unchanged during the adsorption process. Cellulose contact numbers and hydrogen bonding trends on different crystalline surfaces suggest that van der Waals forces and hydrogen bonding interactions drive the binding of proteins to cellulose. These findings reveal the interaction between cellulose and protein at the molecular level and provide theoretical guidance for the design and synthesis of cellulose/spider silk protein composites. METHODS: MD simulations were all performed using the GROMACS-5.1 software package and run with CHARMM36 carbohydrate force field. Molecular dynamics simulations were performed for 500 ns for the simulated system.


Subject(s)
Cellulose , Hydrogen Bonding , Molecular Dynamics Simulation , Silk , Spiders , Cellulose/chemistry , Spiders/chemistry , Animals , Silk/chemistry , Adsorption , Protein Binding , Fibroins/chemistry
2.
J Biomol Struct Dyn ; : 1-13, 2024 Mar 18.
Article in English | MEDLINE | ID: mdl-38497800

ABSTRACT

The hydrolysis of lignocellulose into fermentable monosaccharides using cellulases represents a critical stage in lignocellulosic bioconversion. However, the inactivation of cellulase in the presence of lignin is attributed to the high cost of biofinery. To address this challenge, a comprehensive investigation into the structure-function relationship underlying lignin-driven cellulase inactivation is essential. In this study, molecular docking and molecular dynamics (MD) simulations were employed to explore the impacts of lignin fragments on the catalytic efficiency of cellulase at the atomic level. The findings revealed that soluble lignin fragments and cellulose could spontaneously form stable complexes with cellulase, indicating a competitive binding scenario. The enzyme's structure remained unchanged upon binding to lignin. Furthermore, specific amino acid residues have been identified as involved in interactions with lignin and cellulose. Hydrophobic interactions were found to dominate the binding of lignin to cellulase. Based on the mechanisms underlying the interactions between lignin fragments and cellulase, decreased hydrophobicity and change in the charge of lignin may mitigate the inhibition of cellulase. Furthermore, site mutations and chemical modification are also feasible to improve the efficiency of cellulase. This study may contribute valuable insights into the design of more lignin-resistant enzymes and the optimization of lignocellulosic pretreatment technologies.Communicated by Ramaswamy H. Sarma.

3.
ACS Nano ; 18(11): 8437-8451, 2024 Mar 19.
Article in English | MEDLINE | ID: mdl-38501308

ABSTRACT

Molecular imaging in the second near-infrared window (NIR-II) provides high-fidelity visualization of biopathological events in deep tissue. However, most NIR-II probes produce "always-on" output and demonstrate poor signal specificity toward biomarkers. Herein, we report a series of hemicyanine reporters (HBCs) with tunable emission to NIR-II window (715-1188 nm) and structurally amenable to constructing activatable probes. Such manipulation of emission wavelengths relies on rational molecular engineering by integrating benz[c,d]indolium, benzo[b]xanthonium, and thiophene moieties to a conventional hemicyanine skeleton. In particular, HBC4 and HBC5 possess bright and record long emission over 1050 nm, enabling improved tissue penetration depth and superior signal to background ratio for intestinal tract mapping than NIR-I fluorophore HC1. An activatable inflammatory reporter (AIR-PE) is further constructed for pH-triggered site-specific release in colon. Due to minimized background interference, oral gavage of AIR-PE allows clear delineation of irritated intestines and assessment of therapeutic responses in a mouse model of inflammatory bowel disease (IBD) through real-time NIRF-II imaging. Benefiting from its high fecal clearance efficiency (>90%), AIR-PE can also detect IBD and evaluate the effectiveness of colitis treatments via in vitro optical fecalysis, which outperforms typical clinical assays including fecal occult blood testing and histological examination. This study thus presents NIR-II molecular scaffolds that are not only applicable to developing versatile activatable probes for early diagnosis and prognostic monitoring of deeply seated diseases but also hold promise for future clinical translations.


Subject(s)
Carbocyanines , Inflammatory Bowel Diseases , Optical Imaging , Animals , Mice , Prognosis , Optical Imaging/methods , Fluorescent Dyes , Inflammatory Bowel Diseases/diagnostic imaging , Early Diagnosis
4.
Anal Chem ; 95(17): 6931-6939, 2023 05 02.
Article in English | MEDLINE | ID: mdl-37074795

ABSTRACT

Delayed wound healing is one of the major diabetes complications that occur in 25% of diabetic patients. Specific wound management and combination treatment are required to repair the wound, which still remains a challenge with few effective therapies available currently. In this work, a new H2S donor PRO-F, which is characterized by the capability to promote wound healing in diabetes, was designed. PRO-F can be activated by light without consuming endogenous substances and the accompanying fluorescent signal makes the real-time tracking of released H2S possible. PRO-F is able to deliver H2S in an intracellular environment with moderate release efficiency (50%), which presents cytoprotective effects against excessive reactive oxygen species (ROS) induced damage. Furthermore, the potential of PRO-F to enhance chronic wound healing was validated by employing diabetic models. This work provides new insights into the therapeutic role of H2S donors in complex wound conditions, which should advance the pathophysiological research associated with H2S.


Subject(s)
Diabetes Complications , Hydrogen Sulfide , Humans , Fluorescence , Reactive Oxygen Species , Wound Healing
5.
Chemosphere ; 324: 138227, 2023 May.
Article in English | MEDLINE | ID: mdl-36858120

ABSTRACT

Hypochlorous acid (HClO) and derivative ionic form (ClO-) are significant components of reactive oxygen species, and thus various diseases are correlatively related to the concentration of ClO-. Recently, paper-based indicators have been confirmed to be efficient strategy for sensing hazardous and noxious substances. However, most of these materials can only achieve qualitative detection of the substrates. Herein, an extremely simple manufacturing strategy was proposed to convert commonly-used paper into nano-engineered fluorescent biomass-based platform (CMJL-FP) integrated with on-demand self-assembled colorimetric and ratiometric fluorescence sensor (CMJL) for rapid ClO- quantitative detection in organisms or water sources using smartphones. The CMJL exhibited a highly selective and sensitive ratiometric response to ClO- at a low detection limit (LOD = 92.6 nM). The associating interactions between the fluorescence nano-particles and micro-nano fibers of CMJL-FP ensure good-stability during ClO- detection. It has been experimentally demonstrated that CMJL-FP allows one to realize the rapid quantitative detection of ClO- ions in living cells and large-scale water sources by using color recognition software as part of a simple smartphone. Therefore, integrating the proposed fluorescent paper with smartphones provides an effective, sustainable, cheap and conceptual strategy for quantitative detection of hazardous and noxious substances in organisms and environments.


Subject(s)
Fluorescent Dyes , Water , Fluorescent Dyes/chemistry , Biomass , Hypochlorous Acid/chemistry , Colorimetry , Ions
6.
J Comput Aided Mol Des ; 37(1): 39-51, 2023 01.
Article in English | MEDLINE | ID: mdl-36427107

ABSTRACT

Cellulose/collagen composites have been widely used in biomedicine and tissue engineering. Interfacial interactions are crucial in determining the final properties of cellulose/collagen composite. Molecular dynamics simulations were carried out to gain insights into the interactions between cellulose and collagen. It has been found that the structure of collagen remained intact during adsorption. The results derived from umbrella sampling showed that (110) and ([Formula: see text]) faces exhibited the strongest affinity with collagen (100) face came the second and (010) the last, which could be attributed to the surface roughness and hydrogen-bonding linkers involved water molecules. Cellulose planes with flat surfaces and the capability to form hydrogen-bonding linkers produce stronger affinity with collagen. The occupancy of hydrogen bonds formed between cellulose and collagen was low and not significantly contributive to the binding affinity. These findings provided insights into the interactions between cellulose and collagen at the molecular level, which may guide the design and fabrication of cellulose/collagen composites.


Subject(s)
Cellulose , Molecular Dynamics Simulation , Cellulose/chemistry , Collagen , Hydrogen Bonding , Thermodynamics , Hydrogen
7.
ACS Nano ; 16(6): 8928-8938, 2022 06 28.
Article in English | MEDLINE | ID: mdl-35687786

ABSTRACT

Cellulose nanomaterials, such as cellulose nanocrystals (CNCs), have received enormous attention in various material research fields due to their unique properties and green/sustainable nature, among other qualities. Herein, we report hollow-type annular cellulose nanocrystals (HTA-CNCs), which are generated by following a high-intensity ultrasonic treatment. The advanced aberration-corrected transmission electron microscopy results reveal that HTA-CNCs exhibit ring structures with a typical diameter of 10.0-30.0 nm, a width of 3.0-4.0 nm, and a thickness of 2.0-5.0 nm, similar to those of elementary crystallites. The X-ray diffraction measurements show that the as-prepared HTA-CNCs maintain the cellulose I structure. The changes in structure and hydrogen-bonding characteristics of HTA-CNCs are further determined based on the FT-IR results after deconvolution fitting, showing that three types of hydrogen bonds decrease and the content of free OH increases in HTA-CNCs compared with those in the original CNCs. Furthermore, molecular dynamics simulation is carried out to support the experimental study. The formation of HTA-CNCs might be attributed to the structural change and entropy increase. The hollow-type annular CNCs may have broad value-added applications as cellulose nanomaterials in different fields.


Subject(s)
Cellulose , Nanoparticles , Cellulose/chemistry , Spectroscopy, Fourier Transform Infrared , Ultrasonics , Nanoparticles/chemistry , X-Ray Diffraction
8.
Anal Chem ; 94(15): 5805-5813, 2022 04 19.
Article in English | MEDLINE | ID: mdl-35380780

ABSTRACT

Early diagnosis of rheumatoid arthritis (RA) is crucial to prevent deterioration and improve the prognosis of disease outcome. However, current clinical diagnostic methods are unable to achieve accurate and early detection of RA. In this work, we designed an activatable organic nanoprobe (ONP-CySe) capable of specific and real-time imaging of ClO- in early RA. ONP-CySe comprises a near-infrared fluorescent selenomorpholine-caged cyanine dye as the sensing component and an amphiphilic triblock copolymer triphenyl phosphine derivative for mitochondria targeting. Our results showed that ONP-CySe successfully detected elevated levels of ClO- in the mitochondria of macrophages with high selectivity, low limit of detection (31.5 nM), excellent photostability, and good biocompatibility. Furthermore, ONP-CySe can also be used to monitor anti-inflammatory responses and efficacies of RA therapeutics, such as selenocysteine and methotrexate, in BALB/c mouse models. Therefore, our research proposes a universal molecular design strategy for the detection of ClO-, which holds potential for early diagnosis and drug screening for RA.


Subject(s)
Arthritis, Rheumatoid , Hypochlorous Acid , Animals , Arthritis, Rheumatoid/diagnostic imaging , Early Diagnosis , Fluorescent Dyes , Mice , Mice, Inbred BALB C
9.
ACS Biomater Sci Eng ; 8(3): 1320-1328, 2022 03 14.
Article in English | MEDLINE | ID: mdl-35184561

ABSTRACT

Electrochromic devices (ECDs) are in high demand for many applications; however, there is no ideal method to achieve the full recycling of the substrate and the functional layer in ECDs. Currently, it is still challenging to access ECDs with excellent electrochromic property, good degradability, and facile recycling capability. In this study, high-performance ECDs are successfully fabricated by using poly(3,4-ethylene dioxythiophene):poly(styrenesulfonate) as the functional layer and transparent gelatin film (TGF) derived from pigskin as the substrate. Compared with PET films or PET-based ECDs, the optical transmittance of TGF and the coloration efficiency of our ECDs could be increased by 3.2 and 41.4%, respectively, showing a great potential to replace conventional plastic-based ECDs. Furthermore, the TGF not only showed good biodegradability but also could be regenerated via a simple process without the loss of desirable properties. In addition, the functional layer and substrate can be easily separated in water due to the adjusted interactions of the interface and the unique property of gelatin, which may open a new path for fabricating green electronics.

10.
Cell Signal ; 93: 110277, 2022 05.
Article in English | MEDLINE | ID: mdl-35131454

ABSTRACT

Activation of signal transducer and activator of transcription 3 (STAT3) is associated with hypoxia-induced epithelial-mesenchymal transition (EMT). Activation of STAT3 requires its phosphorylated form, and STAT3 can also be post-translationally modified by O-GlcNAcylation. Dynamic regulation of STAT3 O-GlcNAcylation in relation to STAT3 phosphorylation remains poorly understood. We observed, based on chemical enzyme labeling and click chemistry methods in combination with mass spectrometric analysis, that O-GlcNAcylation of STAT3 is significantly reduced under hypoxia. Results of functional experiments indicated that O-GlcNAcylation maintains stability of STAT3 and prevents its degradation via ubiquitination during hypoxia-induced EMT. O-GlcNAcylation of STAT3 facilitated its phosphorylation. Following STAT3 phosphorylation, existing STAT3 O-GlcNAcylation was antagonistically released. Our experimental findings, in combination with structure modeling, indicate that O-GlcNAcylation of STAT3 at residue T717 is essential for its phosphorylation at Y705. In contrast, mutation of STAT3 at phosphorylation site Y705 had no effect on its O-GlcNAcylation. O-GlcNAcylation and phosphorylation of STAT3 evidently occur in a strict sequential order under hypoxia-induced EMT. Dynamic regulation of STAT3 function clearly involves crosstalk between O-GlcNAcylation and phosphorylation. O-GlcNAcylation of STAT3 at T717 facilitates EMT process by promoting STAT3 phosphorylation, and provides a potential therapeutic target that may be useful in anticancer drug design.


Subject(s)
Epithelial-Mesenchymal Transition , STAT3 Transcription Factor , Epithelial-Mesenchymal Transition/genetics , Humans , Hypoxia , Phosphorylation , STAT3 Transcription Factor/metabolism , Ubiquitination
11.
J Pineal Res ; 71(3): e12765, 2021 Oct.
Article in English | MEDLINE | ID: mdl-34487576

ABSTRACT

Melatonin helps to maintain circadian rhythm, exerts anticancer activity, and plays key roles in regulation of glucose homeostasis and energy metabolism. Glycosylation, a form of metabolic flux from glucose or other monosaccharides, is a common post-translational modification. Dysregulated glycosylation, particularly O-GlcNAcylation, is often a biomarker of cancer cells. In this study, elevated O-GlcNAc level in bladder cancer was inhibited by melatonin treatment. Melatonin treatment inhibited proliferation and migration and enhanced apoptosis of bladder cancer cells. Proteomic analysis revealed reduction in cyclin-dependent-like kinase 5 (CDK5) expression by melatonin. O-GlcNAc modification determined the conformation of critical T-loop domain on CDK5 and further influenced the CDK5 stability. The mechanism whereby melatonin suppressed O-GlcNAc level was based on decreased glucose uptake and metabolic flux from glucose to UDP-GlcNAc, and consequent reduction in CDK5 expression. Melatonin treatment, inhibition of O-GlcNAcylation by OSMI-1, or mutation of key O-GlcNAc site strongly suppressed in vivo tumor growth. Our findings indicate that melatonin reduces proliferation and promotes apoptosis of bladder cancer cells by suppressing O-GlcNAcylation of CDK5.


Subject(s)
Melatonin , Urinary Bladder Neoplasms , Apoptosis , Cell Proliferation , Cyclins , Humans , Melatonin/pharmacology , N-Acetylglucosaminyltransferases , Proteomics , Urinary Bladder Neoplasms/drug therapy
12.
Front Immunol ; 12: 670626, 2021.
Article in English | MEDLINE | ID: mdl-33968077

ABSTRACT

Fibrinogen-like protein 1 (FGL1), a member of the fibrinogen family, is a specific hepatocyte mitogen. Recently, it has been reported that FGL1 is the main inhibitory ligand of lymphocyte activating gene 3 (LAG3). Furthermore, the FGL1-LAG3 pathway has a synergistic effect with programmed death 1 (PD-1)/programmed death ligand 1 (PD-L1) pathway and is regarded as a promising immunotherapeutic target. However, swine FGL1 (sFGL1) has not been characterized and its detection method is lacking. In the study, the sFGL1 gene was amplified from the liver tissue of swine and then inserted into a prokaryotic expression vector, pQE-30. The recombinant plasmid pQE30-sFGL1 was transformed into JM109 competent cells. The recombinant sFGL1 was induced expression by isopropyl-ß-d-thiogalactoside (IPTG) and the purified sFGL1 was used as an antigen to produce mouse monoclonal antibody (mAb) and rabbit polyclonal antibody (pAb). After identification, a double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) for sensitive and specific detection of sFGL1 was developed. Swine FGL1 in samples was captured by anti-sFGL1 mAb followed by detection with anti-sFGL1 rabbit pAb and HRP-conjugated goat anti-rabbit IgG. The limit of detection of the developed sFLG1-DAS-ELISA is 35 pg/ml with recombinant sFLG1. Besides, it does not show cross-reactivity with the control protein. Then serum samples of PRRSV-negative and -positive pigs were tested with the established DAS-ELISA and calculated according to the equation of y=0.0735x+0.0737. The results showed that PRRSV infection enhanced the serum FGL1 levels significantly. Our research provides a platform for the research on the functional roles of swine FGL1.


Subject(s)
Enzyme-Linked Immunosorbent Assay/methods , Fibrinogen/isolation & purification , Hepatocytes/physiology , Immunotherapy/methods , Animals , Antibodies, Monoclonal/metabolism , B7-H1 Antigen/metabolism , Cells, Cultured , Enzyme Assays , Fibrinogen/genetics , Mice , Programmed Cell Death 1 Receptor/metabolism , Sensitivity and Specificity , Signal Transduction , Swine
13.
Anal Chem ; 93(11): 4894-4901, 2021 03 23.
Article in English | MEDLINE | ID: mdl-33689305

ABSTRACT

Hydrogen sulfide (H2S) is a vital endogenous signal molecule that exerts critical physiological functions such as biological regulation and cytoprotection. Despite significant progress in developing H2S donors, site-specific delivery and controllable release of H2S in biological systems remain a key challenge. Herein, we develop new Cys-triggered fluorescent H2S donor Pro-S that is composed of a dicyanoisophorone-based near-infrared (NIR) fluorescent dye and a thiocarbamate moiety. The H2S donor releases H2S under the attack of Cys, accompanied by the release of a fluorescent reporter, which enables the real-time capturing of H2S by fluorescence spectroscopy or microscopy. Pro-S exhibits strong NIR fluorescence enhancement (70-fold), excellent controllable H2S release (30 min), high H2S release efficiency (62%), and well live-cell compatibility, allowing for visualization of H2S release in cells and zebrafish. Moreover, Pro-S presents a good effect of anti-inflammation in RAW 264.7 cells. This work provides a new idea for the design of H2S donors, which may be beneficial to the comprehension of the potential mechanism of inflammation and optimization of treatment strategies.


Subject(s)
Hydrogen Sulfide , Animals , Fluorescent Dyes , HeLa Cells , Humans , Inflammation , Zebrafish
14.
J Am Chem Soc ; 142(32): 13823-13832, 2020 08 12.
Article in English | MEDLINE | ID: mdl-32667195

ABSTRACT

Despite widespread use of heterogeneous Pd catalysts in Suzuki-Miyaura coupling reactions, detailed roles of Pd, especially the nature of its active species, are still a topic of controversial debate. While some studies showed an active surface of Pd nanoparticles or nanoclusters acting heterogeneously, others claimed soluble Pd species leached from the metallic Pd to be active species which are homogeneous in nature. Besides, within the homogeneous mechanism, how the Pd leaches and promotes the cross-coupling reaction is then another question that needs to be addressed. It could be envisioned that if the soluble Pd species and solid-phase Pd are physically separated, the mechanism of Suzuki-Miyaura coupling could then be confirmed through examining the catalytic activity in different reaction regions. Herein we use microporous Stöber silica as a membrane to separate the soluble Pd species from solid Pd and conduct size-selective reactions which allow the passage of leaching Pd species, but not of reactants or products larger than the membrane aperture. With this strategy, we have been able to differentiate the surface reaction from the solution cross-coupling. We find that the leached Pd species are the only genuine catalytic intermediate in the cross-coupling reactions. We also confirm that oxidative addition of aryl halides to the solid Pd leads to leaching of the soluble Pd species which is necessary to promote Suzuki-Miyaura reactions.

15.
Talanta ; 217: 121085, 2020 Sep 01.
Article in English | MEDLINE | ID: mdl-32498866

ABSTRACT

Constructing imprinting materials with high recognition and selectivity for protein is an always challenge in protein imprinting technology (PIT). In this work, upon the participating of a zwitterionic polymer chain (Poly (1-vinyl-3-sulfopropylimidazolium), PVSP), a lysozyme imprinted core-shell carbon microsphere (CFC-PVSP@MIPs) was prepared by combining template immobilization method and surface imprinting technology. The carboxyl-functionalized carbon microspheres as substrate provided the CFC-PVSP@MIPs satisfactory adsorption capacity (68.1 mg g-1), while the dopamine as a functional monomer and crosslinker allowed the imprinted microspheres to have a thin imprinted shell, thus endowing them a fast adsorption equilibrium rate (120 min). In addition, PVSP could be tightly bound to the imprinted layer through non-covalent interaction, which not only simplified the preparation process of CFC-PVSP@MIPs, but also reduced the non-specific adsorption of imprinted material on proteins. Therefore, the resulting CFC-PVSP@MIPs exhibited a more superior recognition ability towards lysozyme with imprinting factor value of 3.10, compared with the PVSP-free imprinted microsphere (imprinting factor value 1.93). Furthermore, benefiting from the characteristics of zwitterionic groups, CFC-PVSP@MIPs also revealed stronger selectivity in competitive adsorption studies of binary protein mixture samples. Consequently, the proposed strategy would be a promising and convenient way to obtain protein imprinted material with high recognition ability, thus would be conducive to further development and application of PIT.

16.
Anal Chem ; 92(8): 5733-5740, 2020 04 21.
Article in English | MEDLINE | ID: mdl-32193934

ABSTRACT

Small-molecular fluorescence sensors have become promising detection tools in many fields attributing to their high sensitivity, excellent temporal and spatial resolution, and low cytotoxicity. However, high concentration or aggregation-induced fluorescence quenching effect has usually hindered the development of traditional fluorescence dyes. Herein, a new fluorophore cyanovinylene dye BMZ with excimer emission property has been constructed. It shows an obvious enhanced and red-shift emission upon aggregation in aqueous solution, which overmatches the conventional pyrene with longer absorption and emission wavelengths. Using this unique optical property, a new fluorescence probe BMZ-Gal has been developed for trapping of ß-galactosidase (ß-Gal) activity with high selectivity, low limit of detection of 0.17 U, and rapid recognition, which is based on the ß-Gal-induced formation of red-shift emitting excimer. ß-Gal has a strong affinity for BMZ-Gal, which is verified through the Michaelis-Menten constants (Km, 1.87 µM) and the hydrolysis efficiencies (Kcat/Km, 1.78 × 103 M-1 s-1). Furthermore, the assay system has been successfully used for detecting endogenous ß-Gal in living ovarian cancer cells and can passively targeted to identify ß-Gal in organelle level and determine its subcellular location with satisfactory accuracy. We anticipate that the new fluorophore cyanovinylene dye herein may inaugurate new opportunities for the development of excimer emission sensors.


Subject(s)
Fluorescent Dyes/chemistry , Ovarian Neoplasms/enzymology , beta-Galactosidase/analysis , Female , Fluorescent Dyes/chemical synthesis , Humans , Molecular Structure , Optical Imaging , Ovarian Neoplasms/diagnostic imaging , Spectrometry, Fluorescence , Tumor Cells, Cultured , beta-Galactosidase/metabolism
17.
Adv Sci (Weinh) ; 6(21): 1901173, 2019 Nov 06.
Article in English | MEDLINE | ID: mdl-31728282

ABSTRACT

Biological gels generally require polymeric chains that produce long-lived physical entanglements. Low molecular weight colloids offer an alternative to macromolecular gels, but often require ad-hoc synthetic procedures. Here, a short biomimetic peptide composed of eight amino acid residues derived from squid sucker ring teeth proteins is demonstrated to form hydrogel in water without any cross-linking agent or chemical modification and exhibits a stiffness on par with the stiffest peptide hydrogels. Combining solution and solid-state NMR, circular dichroism, infrared spectroscopy, and X-ray scattering, the peptide is shown to form a supramolecular, semiflexible gel assembled from unusual right-handed 310-helices stabilized in solution by π-π stacking. During gelation, the 310-helices undergo conformational transition into antiparallel ß-sheets with formation of new interpeptide hydrophobic interactions, and molecular dynamic simulations corroborate stabilization by cross ß-sheet oligomerization. The current study broadens the range of secondary structures available to create supramolecular hydrogels, and introduces 310-helices as transient building blocks for gelation via a 310-to-ß-sheet conformational transition.

18.
J Phys Chem B ; 123(42): 8853-8860, 2019 10 24.
Article in English | MEDLINE | ID: mdl-31557037

ABSTRACT

It was observed in experiments that the catalytic domain (CD) of Trichoderma reesei Cel7A (TrCel7A) hydrolyzes crystalline cellulose in a processive manner, but the underlying binding mechanism is still unknown. Here, through replica-exchange molecular dynamics simulations, we find that the loading and sucking-in process of the cellulose chain into CD is entropy-driven and enthalpy-unfavorable, which firmly relate to the desolvation of the binding channel of CD. During the loading process, hydrophobic interactions play a dominant role because several aromatic residues have been identified to guide the cellulose chain processing. At the active site, a transition from enthalpy- to entropy-driven is detected for the driving force. Such a finding reveals the indispensability of the catalytic reaction of the glycosidic bond to provide the energy to drive the movements of the cellulose chain. Our study reveals the interaction pictures between the cellulose chain and TrCel7A at the atomic level, which helps better understand the catalytic mechanism of TrCel7A.


Subject(s)
Cellulose 1,4-beta-Cellobiosidase/metabolism , Cellulose/chemistry , Cellulose/metabolism , Thermodynamics , Amino Acid Sequence , Cellulose 1,4-beta-Cellobiosidase/genetics , Models, Molecular , Molecular Dynamics Simulation , Protein Conformation , Protein Domains , Trichoderma/enzymology
19.
Small ; 15(6): e1804678, 2019 02.
Article in English | MEDLINE | ID: mdl-30637936

ABSTRACT

Synthetic water channels offer great promise to replace natural aquaporins (AQPs) for making new-generation biomimetic membranes for water treatment. However, the water permeability of the current synthetic water channels is still far below that of AQPs. Here, peptide-attached (pR)-pillar[5]arene (pR-PH) channels are reported to mimic the high permeability of AQPs. It is demonstrated that the pR-PH channels with an open pore can transport water smoothly and efficiently. The pR-PH channels are competitive with AQPs in terms of water permeability and are much superior to diastereomer peptide-attached (pS)-pillar[5]arene (pS-PH) and other reported synthetic water channels. The exceptional water-transport properties of the pR-PH channels are further demonstrated in a composite polymeric membrane that incorporates the nanochannels into the top selective layer. This membrane gives a significantly improved water flux while retaining high salt rejection. The results establish a tangible foundation for developing highly efficient artificial water channel-based biomimetic membrane for water purification applications.

20.
Chem Sci ; 11(3): 618-630, 2019 Nov 22.
Article in English | MEDLINE | ID: mdl-34123034

ABSTRACT

Theranostics that integrates diagnosis and treatment modalities has attracted great attention due to its abilities of personalized therapy and real-time monitoring of therapeutic outcome. Such a theranostic paradigm requires agents to simultaneously possess the capabilities of targeting, imaging, and treatment. Activatable molecular agents (AMAs) are promising for cancer theranostics, as they show a higher signal-to-noise ratio (SNR), real-time detection of cancer-associated biomarkers, lower normal tissue toxicity, and a higher therapeutic effect. This perspective summarizes the recent advancements of AMAs, which include imaging-guided chemotherapy, imaging-guided photodynamic therapy, and imaging-guided photothermal therapy. The molecular design principles, theranostic mechanisms, and biomedical applications of AMAs are described, followed by a discussion of potential challenges of AMAs in cancer theranostics.

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