Conformational Changes Research Articles

Quantum Dot‐Based FRET Nanosensors for Talin‐Membrane Assembly and Mechanosensing

Understanding the mechanisms of assembly and disassembly of macromolecular structures in cells relies on solving biomolecular interactions. However, those interactions often remain unclear because tools to track molecular dynamics are not sufficiently resolved in time or space. In this study, we present a straightforward method for resolving inter‐ and intra‐molecular interactions in cell adhesive machinery, using quantum dot (QD) based Förster resonance energy transfer (FRET) nanosensors. Using a mechanosensitive protein, talin, one of the major components of focal adhesions, we are investigating the mechanosensing ability of proteins to sense and respond to mechanical stimuli. First, we quantified the distances separating talin and a giant unilamellar vesicle membrane for three talin variants. These variants differ in molecular length. Second, we investigated the mechanosensing capabilities of talin, i.e., its conformational changes due to mechanical stretching initiated by cytoskeleton contraction. Our results suggest that in early focal adhesion, talin undergoes stretching, corresponding to a decrease in the talin‐membrane distance of 2.5 nm. We demonstrate that QD‐FRET nanosensors can be applied for the sensitive quantification of mechanosensing with a sub‐nanometer accuracy.

Applications of native mass spectrometry and ultraviolet photodissociation in protein structure and interaction analysis

Dynamic changes in the structures and interactions of proteins are closely correlated with their biological functions. However, the precise detection and analysis of these molecules are challenging. Native mass spectrometry (nMS) introduces proteins or protein complexes into the gas phase by electrospray ionization, and then performs MS analysis under near-physiological conditions that preserve the folded state of proteins and their complexes in solution. nMS can provide information on stoichiometry, assembly, and dissociation constants by directly determining the relative molecular masses of protein complexes through high-resolution MS. It can also integrate various MS dissociation technologies, such as collision-induced dissociation (CID), surface-induced dissociation (SID), and ultraviolet photodissociation (UVPD), to analyze the conformational changes, binding interfaces, and active sites of protein complexes, thereby revealing the relationship between their interactions and biological functions. UVPD, especially 193 nm excimer laser UVPD, is a rapidly evolving MS dissociation method that can directly dissociate the covalent bonds of protein backbones with a single pulse. It can generate different types of fragment ions, while preserving noncovalent interactions such as hydrogen bonds within these ions, thereby enabling the MS analysis of protein structures with single-amino-acid-site resolution. This review outlines the applications and recent progress of nMS and UVPD in protein dynamic structure and interaction analyses. It covers the nMS techniques used to analyze protein-small-molecule ligand interactions, the structures of membrane proteins and their complexes, and protein-protein interactions. The discussion on UVPD includes the analysis of gas-phase protein structures and interactions, as well as alterations in protein dynamic structures, and interactions resulting from mutations and ligand binding. Finally, this review describes the future development prospects for protein analysis by nMS and new-generation advanced extreme UV light sources with higher brightness and shorter pulses.

Conformational changes induced by cellulose nanocrystals in collaboration with calcium ion improve solubility of pea protein isolate

The low solubility of pea protein isolate (PPI) greatly limits its functional properties and its wide application in food field. Thus, this study investigated the effects and mechanisms of cellulose nanocrystals (CNC) (0.1–0.4 %) and CaCl2 (0.4–1.6 mM) on the solubility of PPI. The results showed that the synergistic effect of CNC (0.3 %) and Ca2+ (1.2 mM) increased the solubility of PPI by 242.31 %. CNC and Ca2+ changed the molecular conformation of PPI, enhanced intermolecular forces, and thus induced changes in the molecular morphology of PPI. Meanwhile, the turbidity of PPI decreased, while surface hydrophobicity, the absolute zeta potential value, viscoelasticity, β-sheet ratio, and thermal properties increased. CNC bound to PPI molecules through van der Waals force and hydrogen bond. Ca2+ could strengthen the crosslinking between CNC and PPI. In summary, it is proposed a valuable combination method to improve the solubility of PPI, and it is believed that this research is of great significance for expanding the application fields of PPI and modifying plant proteins.

Advancing molecular understanding in high moisture extrusion for plant-based meat analogs: Challenges and perspectives

In recent years, meat analogs based on plant proteins have received increasing attention. However, the process of high moisture extrusion (HME), the method for their preparation, has not been thoroughly explored, particularly in terms of elucidating the complex interactions that occur during extrusion, which remain challenging. These interactions arise from the various ingredients added during HME, including proteins, starches, edible gums, dietary fibers, lipids, and enzymes. These ingredients undergo intricate conformational changes and interactions under extreme conditions of high temperature, pressure, and shear, ultimately forming the fibrous structure of meat analogs. This review offers a overview of these ingredients and the molecular interaction changes they undergo during the extrusion process. Additionally, it delves into the major molecular interactions such as disulfide bonding, hydrogen bonding, and hydrophobic interactions, providing detailed insights into each.

Structural insight into the functional regulation of Elongation factor Tu by reactive oxygen species in Synechococcus elongatus PCC 7942

In cyanobacteria, Elongation factor Tu (EF-Tu) plays a crucial role in the repair of photosystem II (PSII), which is highly susceptible to oxidative stress induced by light exposure and regulated by reactive oxygen species (ROS). However, the specific molecular mechanism governing the functional regulation of EF-Tu by ROS remains unclear. Previous research has shown that a mutated EF-Tu, where C82 is substituted with a Ser residue, can alleviate photoinhibition, highlighting the important role of C82 in EF-Tu photosensitivity. In this study, we elucidated how ROS deactivate EF-Tu by examining the crystal structures of EF-Tu in both wild-type and mutated form (C82S) individually at resolutions of 1.7 Å and 2.0 Å in Synechococcus elongatus PCC 7942 complexed with GDP. Specifically, the GDP-bound form of EF-Tu adopts an open conformation with C82 located internally, making it resistant to oxidation. Coordinated conformational changes in switches I and II create a tunnel that positions C82 for ROS interaction, revealing the vulnerability of the closed conformation of EF-Tu to oxidation. An analysis of these two structures reveals that the precise spatial arrangement of C82 plays a crucial role in modulating EF-Tu's response to ROS, serving as a regulatory element that governs photosynthetic biosynthesis.

Targeting CCR3 with antagonist SB 328437 sensitizes 5‑fluorouracil‑resistant gastric cancer cells: Experimental evidence and computational insights.

Gastric cancer (GC) ranks fifth globally in cancer diagnoses and third for cancer-related deaths. Chemotherapy with 5-fluorouracil (5-FU), a primary treatment, faces challenges due to the development of chemoresistance. Tumor microenvironment factors, including C-C motif chemokine receptor 3 (CCR3), can contribute to chemoresistance. The present study evaluated the effect of CCR3 receptor inhibition using the antagonist SB 328437 and the molecular dynamics of this interaction on resistance to 5-FU in gastric cancer cells. The 5-FU-resistant AGS cell line (AGS R-5FU) demonstrated notable tolerance to higher concentrations of 5-FU, with a 2.6-fold increase compared with the parental AGS cell line. Furthermore, the mRNA expression levels of thymidylate synthase (TS), a molecular marker for 5-FU resistance, were significantly elevated in AGS R-5FU cells. CCR3 was shown to be expressed at significantly higher levels in these resistant cells. Combining SB 328437 with 5-FU resulted in a significant decrease in cell viability, particularly at higher concentrations of 5-FU. Furthermore, when SB 328437 was combined with 5-FU at a high concentration, the relative mRNA expression levels of CCR3 and TS decreased significantly. Computational analysis of CCR3 demonstrated dynamic conformational changes, especially in extracellular loop 2 region, which indicated potential alterations in ligand recognition. Docking simulations demonstrated that SB 328437 bound to the allosteric site of CCR3, inducing a conformational change in ECL2 and hindering ligand recognition. The present study provides comprehensive information on the molecular and structural aspects of 5-FU resistance and CCR3 modulation, highlighting the potential for therapeutic application of SB 328437 in GC treatment.

How to Choose the Best Optogenetic Tool for Your Research

All-optical methods that provide deeper understanding of neural activity are currently being developed. Optogenetics is a biological technique useful to control neuronal activity or life phenomena using light. Microbial rhodopsins are light-activated membrane proteins used as optogenetic tools. Microbial rhodopsins such as channelrhodopsin2 (ChR2) consist of seven-pass transmembrane proteins with a covalently bound retinal. Light absorption is followed by photoisomerization of the all-trans retinal to a 13-cis configuration and subsequent conformational changes in the molecule, with consequent permeability of the channel structure to ions. Recent studies have reported the discovery of microbial rhodopsins with novel functions. Microbial rhodopsin diversity has also increased. We describe the characteristics of microbial rhodopsins used as optogenetic tools and the latest research in this domain.

Unraveling the Intricacies of Cold-Inducible RNA-Binding Protein: A Comprehensive Review.

Cold-inducible RNA-binding protein (CIRP) is a versatile RNA-binding protein, pivotal in modulating cellular responses to diverse stress stimuli including cold shock, ultraviolet radiation, hypoxia, and infections, with a principal emphasis on cold stress. The temperature range of 32-34°C is most suitable for CIRP expression. The human CIRP is an 18-21kDa polypeptide containing 172 amino acids coded by gene located on chromosome 19p13.3. CIRP has an RNA-recognition motif (RRM) and an arginine-rich motif (RGG), both of which have roles in coordinating numerous cellular activities. CIRP itself also undergoes conformational changes in response to diverse environmental stress. Transcription factors such as hypoxia-inducible factor 1 alpha (HIF-1α) and nuclear factor-kappa B (NF-κB) have been implicated in coordinating CIRP transcription in response to specific stimuli. The potential of CIRP to relocate from the nucleus to the cytoplasm upon exposure to different stimuli enhances its varied functional roles across different cellular compartments. The different functions include decreasing nutritional demand, apoptosis suppression, modulation of translation, and preservation of cytoskeletal integrity at lower temperatures. This review explores the diverse functions and regulatory mechanisms of CIRP, shedding light on its involvement in various cellular processes and its implications in human health and disease.

Stabilization of delphinidin-3-O-rutinoside by mixed β-conglycinin and hydrolysates of glycinin upon heating

The selectively hydrolyzed soy protein composed of β-conglycinin (7S) and glycinin hydrolysates (GH) showed a superior protective effect on the delphinidin-3-O-rutinoside (D3R) during the steaming of colored wheat dough. To clarify the potential mechanism, 7S and GH were isolated and combined in varied ratios to mimic the RG proteins, and the interactions between proteins and D3R were studied by combined multispectral and molecular dynamics simulation study. The results suggested that 7S showed a higher stabilization effect of D3R than GH upon heating. In contrast, the optimum effect was noticed when incorporated with the mixed proteins with equal level of 7S and GH. D3R induced conformational changes of 7S and GH upon heating, and D3R formed complexes with proteins via hydrophobic interactions, and it was a static quenching process. The optimal binding affinity to D3R was observed with equal level of GH and 7S, contributing to enhanced thermal stability. Compared with GH, 7S could bind more amino acids and form a more stable complex with D3R. The results of this study could provide a theoretical basis for the preservation of D3R upon thermal processing and promote the application of mixed soy proteins in the functional food industry.

Interactions between deep eutectic solvents and bovine serum albumin studied by spectroscopic and electrochemical methods

Deep eutectic solvent (DES) has become a potential protein extractant as its good biocompatibility, environmental friendliness and accessibility. In this study, two types of DESs, ferric chloride hexahydrate: oxalic acid (FeCl3·6H2O: H2C2O4) and choline chloride: zinc chloride (ChCl: ZnCl2), were prepared. The interactions between these two types of DESs and bovine serum albumin (BSA) were investigated by utilizing spectroscopic and electrochemical methods. It was found that both FeCl3·6H2O: H2C2O4 and ChCl: ZnCl2 are able to form complexes with BSA by a relatively high affinity. During the process, no significant change in BSA conformation was observed. The binding ratios of BSA in the FeCl3·6H2O: H2C2O4 and ChCl: ZnCl2 systems are up to 98.59 % and 98.14 %, respectively, indicating that the two DESs are both promising extractants for BSA. The interactions between the DESs and BSA are mainly hydrogen bond and van der Waals force, which are strong enough to extract BSA but not too strong for regeneration, making the DESs more applicable in the industry. Moreover, it was found that the binding ratio of BSA in the FeCl3·6H2O: H2C2O4-BSA system remains above 91.7 % in the temperature range of 298–313 K, illustrating the potential of FeCl3·6H2O: H2C2O4 to be used in BSA extraction under a wider range of temperature. In contrast, ChCl: ZnCl2 will be better used under lower temperatures.

TMPRSS2 and glycan receptors synergistically facilitate coronavirus entry.

The entry of coronaviruses is initiated by spike recognition of host cellular receptors, involving proteinaceous and/or glycan receptors. Recently, TMPRSS2 was identified as the proteinaceous receptor for HCoV-HKU1 alongside sialoglycan as a glycan receptor. However, the underlying mechanisms for viral entry remain unknown. Here, we investigated the HCoV-HKU1C spike in the inactive, glycan-activated, and functionally anchored states, revealing that sialoglycan binding induces a conformational change of the NTD and promotes the neighboring RBD of the spike to open for TMPRSS2 recognition, exhibiting a synergistic mechanism for the entry of HCoV-HKU1. The RBD of HCoV-HKU1 features an insertion subdomain that recognizes TMPRSS2 through three previously undiscovered interfaces. Furthermore, structural investigation of HCoV-HKU1A in combination with mutagenesis and binding assays confirms a conserved receptor recognition pattern adopted by HCoV-HKU1. These studies advance our understanding of the complex viral-host interactions during entry, laying the groundwork for developing new therapeutics against coronavirus-associated diseases.

Structural basis of TMPRSS2 zymogen activation and recognition by the HKU1 seasonal coronavirus.

The human seasonal coronavirus HKU1-CoV, which causes common colds worldwide, relies on the sequential binding to surface glycans and transmembrane serine protease 2 (TMPRSS2) for entry into target cells. TMPRSS2 is synthesized as a zymogen that undergoes autolytic activation to process its substrates. Several respiratory viruses, in particular coronaviruses, use TMPRSS2 for proteolytic priming of their surface spike protein to drive membrane fusion upon receptor binding. We describe the crystal structure of the HKU1-CoV receptor binding domain in complex with TMPRSS2, showing that it recognizes residues lining the catalytic groove. Combined mutagenesis of interface residues and comparison across species highlight positions 417 and 469 as determinants of HKU1-CoV host tropism. The structure of a receptor-blocking nanobody in complex with zymogen or activated TMPRSS2 further provides the structural basis of TMPRSS2 activating conformational change, which alters loops recognized by HKU1-CoV and dramatically increases binding affinity.

The molecular determinants of calcium ATPase inhibition by curcuminoids

The natural product curcumin and some of its analogs are known inhibitors of the transmembrane enzyme sarco/endoplasmic reticulum calcium ATPase (SERCA). Despite their widespread use, the curcuminoids' binding site in SERCA and their relevant interactions with the enzyme remain elusive. This lack of knowledge has prevented the development of curcuminoids into valuable experimental tools or into agents of therapeutic value. We used the crystal structures of SERCA in its E1 conformation in conjunction with computational tools such as docking and surface screens to determine the most likely curcumin binding site, along with key enzyme/inhibitor interactions. Additionally, we determined the inhibitory potencies and binding affinities for a small set of curcumin analogs. The predicted curcumin binding site is a narrow cleft in the transmembrane section of SERCA, close to the transmembrane/cytosol interface. In addition to pronounced complementarity in shape and hydrophobicity profiles between curcumin and the binding pocket, several hydrogen bonds were observed that were spread over the entire curcumin scaffold, involving residues on several transmembrane helices. Docking-predicted interactions were compatible with experimental observations for inhibitory potencies and binding affinities. Based on these findings, we propose an inhibition mechanism that assumes that the presence of a curcuminoid in the binding site arrests the catalytic cycle of SERCA by preventing it from converting from the E1 to the E2 conformation. This blockage of conformational change is accomplished by a combination of steric hinderance and hydrogen-bond-based cross-linking of transmembrane helices that require flexibility throughout the catalytic cycle.

Investigation on solvent-free esterification of oleic acid by hemp tea waste-immobilized Candida rugosa lipase

This study aimed at Candida rugosa lipase immobilization on a low-cost and readily available support. Among agro-industrial crops, hemp tea waste was chosen as the carrier because it provides higher immobilization performance than hemp flower and leaf wastes. Support characterization by ATR-FTIR, SEM and elemental analysis and the optimization of the adsorption immobilization process were performed. The lipase adsorption immobilization was obtained by soaking the support with hexane under mild agitation for 2 h and a successively incubating the enzyme for 1 h at room temperature without removing the solvent. The esterification of oleic acid with n-decanol was tested in a solvent-free system by studying some parameters that influence the reaction, such as the substrates molar ratio, the lipase activity/oleic acid ratio, reaction temperature and the presence/absence of molecular sieves. The biocatalyst showed the ability to bring the esterification reaction to equilibrium under 60 min and good reusability (maintaining 60 % of its original activity after three successive esterification reactions) but low conversion (21 %) at the optimized conditions (40 °C, 1:2 substrates molar ratio, 0.56 lipase/oleic acid ratio, without sieves). Comparing the results with those obtained by free lipase form at the same activity (1 U) and experimental conditions, slightly higher conversion (%) appeared for the free lipase. All this highlighted that probably the source of lipase for its carbohydrate-binding pocket and lid structure affected the esterification of oleic acid but certainly, the immobilization didn’t induce any lipase conformational change also allowing the reuse of the catalytic material.

Sampling Conformational Ensembles of Highly Dynamic Proteins via Generative Deep Learning.

Proteins are inherently dynamic, and their conformational ensembles are functionally important in biology. Large-scale motions may govern protein structure-function relationship, and numerous transient but stable conformations of intrinsically disordered proteins (IDPs) can play a crucial role in biological function. Investigating conformational ensembles to understand regulations and disease-related aggregations of IDPs is challenging both experimentally and computationally. In this paper we first introduced an unsupervised deep learning-based model, termed Internal Coordinate Net (ICoN), which learns the physical principles of conformational changes from molecular dynamics (MD) simulation data. Second, we selected interpolating data points in the learned latent space that rapidly identify novel synthetic conformations with sophisticated and large-scale sidechains and backbone arrangements. Third, with the highly dynamic amyloid-β 1-42 (Aβ42) monomer, our deep learning model provided a comprehensive sampling of Aβ42's conformational landscape. Analysis of these synthetic conformations revealed conformational clusters that can be used to rationalize experimental findings. Additionally, the method can identify novel conformations with important interactions in atomistic details that are not included in the training data. New synthetic conformations showed distinct sidechain rearrangements that are probed by our EPR and amino acid substitution studies. This approach is highly transferable and can be used for any available data for training. The work also demonstrated the ability for deep learning to utilize learned natural atomistic motions in protein conformation sampling.

Molecular Docking and Dynamics Studies of Withania somnifera Derived Compounds as GABA-A Receptor Modulators for Insomnia

Objective: This study aimed to identify potential phytochemicals from <i>Withania somnifera</i> (ashwagandha) that can act as gamma-aminobutyric acid A (GABA-A) receptor agonists or stimulant, and evaluate their suitability as potential insomnia treatments. Methods: Various computational approaches were employed, including virtual screening, biological activity prediction, physicochemical and drug-likeness analysis, absorption, distribution, metabolism, excretion, and toxicity (ADME/T) analysis, and molecular dynamics simulations. The Diseases Plants Eliminate (DISPEL) server was used to identify suitable plant species in context to insomnia, and the Indian Medicinal Plants, Phytochemistry And Therapeutics 2.0 (IMPPAT 2.0) database was utilized to assess the phytochemicals from <i>W. somnifera</i>. Virtual screening was performed using AutoDock Vina, and biological activity prediction was carried out using the Prediction of Activity Spectra for Substances (PASS) web server. The SwissADME webserver was used for physicochemical and drug-likeness analysis, while the ADME/T analysis was conducted using the ADMETlab 2.0 and ProTox 3.0 servers. Molecular dynamics simulations were performed using the WEBGRO Macromolecular Simulations server. Results: The findings revealed that hygrine, tropine, and withasomnine exhibited promising GABA-A receptor agonist activity, favorable drug-likeness properties, low toxicity, and stable receptor-ligand interactions. These phytochemicals demonstrated desirable physiochemical properties, adhering to Lipinski’s rule of five, and exhibited favorable ADME profiles. Molecular dynamics simulations showed stable interactions between the compounds and the GABA-A receptor, with minimal conformational changes and high compactness observed for hygrine and tropine. Conclusion: The phytochemicals hygrine, tropine, and withasomnine from <i>W. somnifera</i> emerged as potential lead compounds for the development of novel insomnia treatments targeting the GABA-A receptor. These findings warrant further investigation through experimental validation and optimization to advance their development as potential therapeutic agents for insomnia.

Sampling Conformational Ensembles of Highly Dynamic Proteins via Generative Deep Learning.

Proteins are inherently dynamic, and their conformational ensembles are functionally important in biology. Large-scale motions may govern protein structure-function relationship, and numerous transient but stable conformations of intrinsically disordered proteins (IDPs) can play a crucial role in biological function. Investigating conformational ensembles to understand regulations and disease-related aggregations of IDPs is challenging both experimentally and computationally. In this paper first an unsupervised deep learning-based model, termed Internal Coordinate Net (ICoN), is developed that learns the physical principles of conformational changes from molecular dynamics (MD) simulation data. Second, interpolating data points in the learned latent space are selected that rapidly identify novel synthetic conformations with sophisticated and large-scale sidechains and backbone arrangements. Third, with the highly dynamic amyloid-β1-42 (Aβ42) monomer, our deep learning model provided a comprehensive sampling of Aβ42's conformational landscape. Analysis of these synthetic conformations revealed conformational clusters that can be used to rationalize experimental findings. Additionally, the method can identify novel conformations with important interactions in atomistic details that are not included in the training data. New synthetic conformations showed distinct sidechain rearrangements that are probed by our EPR and amino acid substitution studies. The proposed approach is highly transferable and can be used for any available data for training. The work also demonstrated the ability for deep learning to utilize learned natural atomistic motions in protein conformation sampling.

Molecular dynamics simulations of betaine-based deep eutectic solvents with varying iso-alcohols chain lengths

Betaine-based (BET) deep eutectic solvents (DESs) made with isoalcohols of varying hydrocarbon chain lengths, namely triethylene glycol (TEG), 1, 2-ethanediol (ETD), 1, 3-propanediol (PPD) and 1, 4-butanediol (BTD) were modelled. Their effects on the formation of aqueous biphasic system (ABS) with 2 M dipotassium phosphate salt solution (K2HPO4) as well as the extraction of common protein molecules, bovine serum albumin (BSA), were studied using molecular dynamics simulation with Gromacs. Qualitative and quantitative data were used to analyse the simulation results, which includes visualised systems in equilibrium, root mean square deviation (RMSD), root mean square fluctuation (RMSF), radius of gyration, radial distribution function (RDF) and hydrogen bond analysis. The results and literature research validated the role of inorganic salt solute concentration on the phase forming ability as well as the possibility of protein denaturation. More investigations and experimental works are to be carried out regarding the type of inorganic salt and its concentration for aqueous biphasic systems (ABSs) with alcohol based DESs and salt solution for protein extraction purposes. This is essential to understand the salting-out effect and to isolate the effects of hydrocarbon chain length from other influencing factors. Additionally, inorganic salt concentrations, presence of ether linkage as well as hydrocarbon chain length is shown to play a role in the dynamics between molecules in the system as well as protein conformational changes. Overall, ABS incorporating PPD and BTD with hydrocarbon chain lengths not exceeding C4 demonstrated superior performance in terms of protein conformational stability and interaction, showcasing their efficacy in protein extraction process.

Validation of electron-microscopy maps using solution small-angle X-ray scattering.

The determination of the atomic resolution structure of biomacromolecules isessential for understanding details of their function. Traditionally, such a structure determination has been performed with crystallographic or nuclear resonance methods, but during the last decade, cryogenic transmission electron microscopy (cryo-TEM) has become an equally important tool. As the blotting and flash-freezing of the samples can induce conformational changes, external validation tools are required to ensure that the vitrified samples are representative of the solution. Although many validation tools have already been developed, most of them rely on fully resolved atomic models, which prevents early screening of the cryo-TEM maps. Here, a novel and automated method forperforming such a validation utilizing small-angle X-ray scattering measurements, publicly available through the new software package AUSAXS, is introduced and implemented. The method has been tested on both simulated and experimental data, where it was shown to work remarkably well as a validation tool. The method provides a dummy atomic model derived from the EM map which best represents the solution structure.

Supramolecular Self-Assembled Nanostructures Derived from Amplified Structural Isomerism of Zn(II)-Sn(IV)-Zn(II) Porphyrin Triads and Their Visible Light Photocatalytic Degradation of Pollutants.

Two structural isomeric porphyrin-based triads (Zn(II)porphyrin-Sn(IV)porphyrin-Zn(II)porphyrin) denoted as T1 and T2 were prepared from the reaction of meso-[5-(4-hydroxyphenyl)-10,15,20-tris(3,5-di-tert-butylphenyl)porphyrinato]zinc(II) (ZnL) with trans-dihydroxo-[5,10-bis(3-pyridyl)-15,20-bis(phenyl)porphyrinato]tin(IV) (SnP1) and trans-dihydroxo-[5,15-bis(3-pyridyl)-10,20-bis(phenyl)porphyrinato]tin(IV) (SnP2), respectively. All the compounds were characterized using UV-vis spectroscopy, emission spectroscopy, ESI-MS, 1H NMR spectroscopy, and FE-SEM. Most importantly, the two structurally isomeric porphyrin-based triads supramolecularly self-assembled into completely different nanostructures. T1 exhibits a nanosphere morphology, whereas T2 exhibits a nanofiber morphology. The amplified geometric feature in the structural isomeric porphyrin-based triads dictates the physical and chemical properties of the two triads. Both compounds showed the morphology-dependent visible light catalytic photodegradation of rhodamine B dye (74-97% within 90 min) and tetracycline antibiotic (44-71% within 45 min) in water. In both cases, the photodegradation efficiency of T2 was higher than that of T1. The present investigation can significantly contribute to the remediation of wastewater by tuning the conformational changes in porphyrin-based photocatalysts.