Supramolecular Organization Research Articles

(Invited) Recent Advances in Subphthalocyanines

Subphthalocyanines (SubPcs) [1] are well-known cone-shaped chromophores consisting of three 1,3-diiminoisoindole units assembled around a boron atom. As a result of their 14 pi-electron aromatic core and their tetrahedral geometry, SubPcs exhibit outstanding physical and optoelectronic properties (e.g., strong dipole moment, excellent light absorption in the 550-650 nm, rich redox features, and excellent charge transport capabilities), that have been skilfully used in variety of applied fields, such as molecular photovoltaics, among others. SubPcs were used by us as non-fullerene acceptors in bulk heterojunctions (BHJ) solar cells. On the other hand as part of our systematic investigation in the preparation and study of novel SubPc-based D–A systems, we have used 1,1,4,4-tetracyanobuta-1,3-diene (TCBD) as partner for SubPcs. Moreover, in the case of unsymmetrically substituted SubPcs (i.e., prepared by cyclotrimerization of a phthalonitrile with no C2v symmetry), they present inherent chirality and the corresponding couple of enantiomers can be isolated [2]. Columnar aggregates based on chiral SubPcs have been also prepared, giving rise to ferroelectric self-assembled molecular materials showing both rectifying and switchable conductivity. These chromophores have been incorporated in multicomponent systems showing a panchromatic response and allowing the tuning and controlling intramolecular FÖRSTER Resonance Energy Transfer for Singlet Fission. [1] G. Lavarda, J. Labella, M. V. Martinez-Diaz, M. S. Rodriguez Morgade, A. Osuka, T. Torres, “Recent advances in subphthalocyanines and related subporphyrinoids” Chem. Soc. Rev. 2022, 51, 9482-9619.[2] J. Labella, G. Lavarda, L. Hernández-López, F.Aguilar-Galindo, S.Díaz-Tendero, J. Lobo-Checa, T. Torres “Preparation, Supramolecular Organization, and On-Surface Reactivity of Enantiopure Subphthalocyanines: From Bulk to 2D-Polymerization” J. Am. Chem. Soc. 2022, 144, 16579-16587.

Glomerular proteomic profiling reveals early differences between preexisting and de novo type 2 diabetes in human renal allografts.

Diabetes mellitus (DM), either preexisting or developing after transplantation, remains a crucial clinical problem in kidney transplantation. To obtain insights into the molecular mechanisms underlying PTDM development and early glomerular damage before the development of histologically visible diabetic kidney disease, we comparatively analysed the proteome of histologically normal glomeruli from patients with PTDM and normoglycaemic (NG) transplant recipients. Moreover, to assess specificities inherent in PTDM, we also comparatively evaluated glomerular proteomes from transplant recipients with preexisting type 2 DM (T2DM). Protocol biopsies were obtained from adult NG, PTDM and T2DM patients one year after kidney transplantation. Biopsies were formalin-fixed and embedded in paraffin, and glomerular cross-sections were microdissected. A total of 4 NG, 7 PTDM and 6 T2DM kidney biopsies were used for the analysis. The proteome was determined by liquid chromatography-tandem mass spectrometry. Relative differences in protein abundance and significantly dysregulated pathways were analysed. Proteins involved in cell adhesion, immune response, leukocyte transendothelial filtration, and cell localization and organization were less abundant in glomeruli from PTDM patients than in those from NG patients, and proteins associated with supramolecular fibre organization and protein-containing complex binding were more abundant in PTDM patients. Overall, proteins related to adherens and tight junctions and those related to the immune system, including leukocyte transendothelial migration, were more abundant in NG patients than in transplanted patients with DM, irrespective of the timing of its development. However, proteins included in cell‒cell junctions and adhesion, insulin resistance, and vesicle-mediated transport were all less abundant in PTDM patients than in T2DM patients. The glomerular proteome profile differentiates PTDM from NG and T2DM, suggesting specific pathogenetic mechanisms. Further studies are warranted to validate these results, potentially leading to an improved understanding of PTDM kidney transplant pathophysiology and to the identification of novel biomarkers.

Short Peptides for Hydrolase Supramolecular Mimicry and Their Potential Applications.

Hydrolases are enzymes that have found numerous applications in various industrial sectors spanning from pharmaceuticals to foodstuff and beverages, consumers' products such as detergents and personal care, textiles, and even for biodiesel production and environmental bioremediation. Self-assembling and gelling short peptides have been designed for their mimicry so that their supramolecular organization leads to the creation of hydrophobic pockets for catalysis to occur. Catalytic gels of this kind can also find numerous industrial applications to address important global challenges of our time. This concise review focuses on the last 5 years of progress in this fast-paced, popular field of research with an eye towards the future.

Crystal structures of the complexes containing macrocyclic cations [M(cyclam)]2+ (M = Ni, Zn) and tetra-iodido-cadmate(2-) anion.

The asymmetric units of the isostructural compounds (1,4,8,11-tetra-aza-cyclo-tetra-decane-κ4 N)nickel(II) tetra-iodido-cadmate(II), [Ni(C10H24N4)][CdI4] (I), and tri-iodido-1κ3 I-μ-iodido-(1,4,8,11-tetra-aza-cyclo-tetra-decane-2κ4 N)cad-mium(II)zinc(II), [CdZnI4(C10H24N4)] (II) (C10H24N4 = 1,4,8,11-tetra-aza-cyclo-tetra-decane, cyclam, L), consist of the centrosymmetric macrocyclic cation [M(L)]2+ [M = NiII or ZnII] with the metal ion lying on a twofold screw axis, and the tetra-iodo-cadmate anion [CdI4]2- located on the mirror plane. In I, the anion acts as an uncoordinated counter-ion while in II it is bound to the ZnII atom via one of the iodide atoms, thus forming an electroneutral heterobimetallic complex [Zn(L)(CdI4)]. The NiII and ZnII ions are coordinated in a square-planar manner by the four secondary N atoms of the macrocyclic ligand L, which adopts the most energetically stable trans-III conformation. The [CdI4]2- anions in I and II are structurally very similar and represent slightly deformed tetra-hedrons with average Cd-I bond lengths and I-Cd-I angles of ca 2.79 Å and 109.6°, respectively. The supra-molecular organization of the complexes under consideration in the crystals is very similar and is determined by the hydrogen-bonding inter-actions between the secondary amino groups of the ligand L in the [M(L)]2+ cations and iodide atoms of the [CdI4]2- anion. In particular, the alternating cations and anions form chains running along the b-axis direction that are arranged into di-periodic sheets oriented parallel to the (101) and (01) planes. Because both kinds of sheets are built from the same cations and anions, this feature provides the three-dimensional coherence of the crystals of I and II.

Fibroblast growth factor 2 acts as an upstream regulator of inhibition of pulmonary fibroblast activation.

Fibroblast growth factor (FGF) signaling plays a crucial role in lung development and repair. Fibroblast growth factor 2 (FGF2) can inhibit fibrotic gene expression and suppress the differentiation of pulmonary fibroblasts (PFs) into myofibroblasts in vitro, suggesting that FGF2 is a potential target for inhibiting pulmonary fibrosis. To gain deeper insights into the molecular mechanism underlying FGF2-mediated regulation of PFs, we performed mRNA sequencing analysis to systematically and globally uncover the regulated genes and biological functions of FGF2 in PFs. Gene Ontology analysis revealed that the differentially expressed genes regulated by FGF2 were enriched in multiple cellular functions including extracellular matrix (ECM) organization, cytoskeleton formation, β-catenin-independent Wnt signaling pathway, supramolecular fiber organization, epithelial cell proliferation, and cell adhesion. Gene Set Enrichment Analysis and cellular experiments confirmed that FGF2 can suppress ECM and actin filament organization and increase PFs proliferation. Taken together, these findings indicate that FGF2 acts as an upstream regulator of the inhibition of PFs activation and may play a regulatory role in pulmonary fibrosis.

Novel opportunities from bioimaging to understand the trafficking and maturation of intracellular pulmonary surfactant and its role in lung diseases.

Pulmonary surfactant (PS), a complex mixture of lipids and proteins, is essential for maintaining proper lung function. It reduces surface tension in the alveoli, preventing collapse during expiration and facilitating re-expansion during inspiration. Additionally, PS has crucial roles in the respiratory system's innate defense and immune regulation. Dysfunction of PS contributes to various respiratory diseases, including neonatal respiratory distress syndrome (NRDS), adult respiratory distress syndrome (ARDS), COVID-19-associated ARDS, and ventilator-induced lung injury (VILI), among others. Furthermore, PS alterations play a significant role in chronic lung diseases such as chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF). The intracellular stage involves storing and releasing a specialized subcellular organelle known as lamellar bodies (LB). The maturation of these organelles requires coordinated signaling to organize their intracellular organization in time and space. LB's intracellular maturation involves the lipid composition and critical processing of surfactant proteins to achieve proper functionality. Over a decade ago, the supramolecular organization of lamellar bodies was studied using electron microscopy. In recent years, novel bioimaging tools combining spectroscopy and microscopy have been utilized to investigate the in cellulo intracellular organization of lamellar bodies temporally and spatially. This short review provides an up-to-date understanding of intracellular LBs. Hyperspectral imaging and phasor analysis have allowed identifying specific transitions in LB's hydration, providing insights into their membrane dynamics and structure. A discussion and overview of the latest approaches that have contributed to a new comprehension of the trafficking and structure of lamellar bodies is presented.

Monitoring drug stability by label-free fluorescence lifetime imaging: a case study on liposomal doxorubicin

In a previous report, we demonstrated that Doxorubicin (DOX) intrinsic fluorescence can be exploited in combination with the phasor approach to fluorescence lifetime imaging microscopy (FLIM) and quantitative absorption/fluorescence spectroscopy to resolve the supramolecular organization of the drug within its FDA-approved nanoformulation, Doxil®. The resulting ‘synthetic identity’ comprises three co-existing physical states of the drug within Doxil®: a dominating fraction of crystallized DOX (DOXc >98%), and two minor fractions of free DOX (DOXf∼1%), and DOX associated with the liposomal membrane (DOXb <1%). This result serves as a benchmark here to address the time evolution of Doxil® synthetic identity. We probe the effect of temperature for a total duration of 6 months in a non-invasive way by FLIM. We confirm Doxil® stability if stored at 4°C, while we detect marked changes in its synthetic identity at 37°C: crystallized DOX gets progressively disassembled in time, in favor of the other two physical states, free and membrane-associated DOX. Our phasor-FLIM-based approach paves the way to time-resolved biochemical assays on the supramolecular organization of encapsulated fluorescent drugs potentially all the way from the production phase to their state within living matter.

Enantioselective Self-Replicators.

Self-replicating molecules provide a simple approach for investigating fundamental processes in scenarios of the emergence of life. Although homochirality is an important aspect of life and of how it emerged, the effects of chirality on self-replicators have received only little attention so far. Here, we report several self-assembled self-replicators with enantioselectivity that emerge spontaneously and grow only from enantiopure material. These require a relatively small number of chiral units in the replicators (down to eight) and in the precursors (down to a single chiral unit), compared to the only other enantioselective replicator reported previously. One replicator was found to incorporate material of its own handedness with high fidelity when provided with a racemic mixture of precursors, thus sorting (L)- and (D)-precursors into (L)- and (D)-replicators. Systematic studies reveal that the presence or absence of enantioselectivity depends on structural features (ring size of the replicator) that appear to impose constraints on its supramolecular organization. This work reveals new aspects of the little researched interplay between chirality and self-replication and represents another step toward the de novo synthesis of life.

Peculiarities of some Fmoc-dipeptides gelation in DMSO/water medium

The possibility of the gels formation with a high-water content of 90% v/v using Fmoc-dipeptides without mechanical actions or pH-switching was demonstrated. For the first time, the formation of a colloid gel based on Fmoc-LL dipeptide was discovered. The effect of side substituents in the amino acid residues of Fmoc-dipeptides in the range of GG, AA, LL, and FF on their ability to form gels in DMSO/water systems was thoroughly studied. Non-linear dependence of gel formation kinetics in dipeptide/DMSO/water systems, gel properties, and supramolecular organization in xerogels on the size of side substituents was observed. The results obtained give a new insight into the mechanism of gelation with low-molecular-weight gelators based on Fmoc-dipeptides and may be useful for the preparation of new supramolecular or colloidal gels.

Langmuir-Schaefer films based on cyclotriphosphazene-substituted phthalocyanines: Supramolecular organization, UV/Vis study, and laser-induced nonlinear absorption

Low-defective thin films of 2-hydroxy-9(10),16(17),23(24)-tri-tert-butylphthalocyanine (1), as well as its cyclotriphosphazene-substituted derivatives, monomer (2) and clamshell-like dimer (3), have been obtained and extensively studied. It is shown that these dyes produce stable floating layers with a certain number of three-dimensional aggregates at the air/water interface. The floating layers retain their structure when transferred to a glass substrate by the Langmuir-Schaefer method, demonstrating the H-aggregation of the dyes. In contrast to the initial monohydroxyphthalocyanine 1, thin films of its derivatives, cyclotriphosphazene-substituted monomer 2 and dimer 3, show a slight increase in absorption when the number of deposited layers exceeds 100. It is shown that thin films of the studied dyes 1–3 can be used in the technology of optical limitation of laser radiation, demonstrating a good cutting efficiency of dangerous nanosecond pulses.

Biomimetic mineral layer over layer-by-layer assemblies: Growth mechanism directed by collagen fibrils

In this study, we describe a promising biomimetic method for growing a hybrid calcium phosphate (CaP) – collagen coating designed following the same principles that govern biomineralization of hard tissues. For this purpose, we explore the versatility of layer-by-layer (LbL) method to incorporate type I collagen and alkaline phosphatase (ALP), while controlling their supramolecular organization and bioactivity. This provides a way to generate in situ CaP ion precursors in the vicinity of collagen proteins, which are self-assembled into fibrils at the solid/liquid interface and further crosslinked. The catalytic properties of ALP, including initial activity and operational stability, is evaluated when the enzymes are embedded within the LbL film. Moreover, a systematic study of the intermediate states of the mineralization is performed by means of atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). Results show that the presence of collagen fibrils within the LbL film plays a pivotal role in the growth mechanism of the biomimetic mineral layer. The main findings support that the role of fibrils consists in favoring the adsorption of enzymes and providing a suitable environment for CaP nucleation and growth. Interestingly, early-stage AFM observations reveal the preferential formation of colloidal particles of CaP onto the collagen fibrils, followed by a significant increase of their surface coverage, yielding particles onto and in-between the fibrils. Further mineralization leads to a coating fully covering the support and mainly exhibiting flat and continuous layer covered with a dense network of mineralized collagen fibrils. The approach described in this work provides a straightforward way for the design of biomimetic hybrid coatings with the perspective of tuning cell-material interaction in biomedical applications dealing with hard mineralized tissues.

Novel Insight into the Photophysical Properties and 2D Supramolecular Organization of Poly(3,4-ethylenedioxythiophene)/Permodified Cyclodextrins Polyrotaxanes at the Air-Water Interface.

Two poly(3,4-ethylenedioxythiophene) polyrotaxanes (PEDOT∙TMe-βCD and PEDOT∙TMe-γCD) end-capped by pyrene (Py) were synthesized by oxidative polymerization of EDOT encapsulated into TMe-βCD or TMe-γCD cavities with iron (III) chloride (FeCl3) in water and chemically characterized. The effect of TMe-βCD or TMe-γCD encapsulation of PEDOT backbones on the molecular weight, thermal stability, and solubility were investigated in depth. UV-vis absorption, fluorescence (FL), phosphorescence (PH), quantum efficiencies, and lifetimes in water and acetonitrile were also explored, together with their surface morphology and electrical properties. Furthermore, dynamic light scattering was used to study the hydrodynamic diameter (DH) and z-potential (ZP-ζ) of the water soluble fractions of PEDOT∙TMe-βCD and PEDOT∙TMe-γCD. PEDOT∙TMe-βCD and PEDOT∙TMe-γCD exhibited a sharp monodisperse peak with a DH of 55 ± 15 nm and 122 ± 32 nm, respectively. The ZP-ζ value decreased from -31.23 mV for PEDOT∙TMe-βCD to -20.38 mV for PEDOT∙TMe-γCD, indicating that a negatively charged layer covers their surfaces. Surface pressure-area isotherms and Brewster angle microscopy (BAM) studies revealed the capability of the investigated compounds to organize into sizeable and homogeneous 2D supramolecular assemblies at the air-water interface. The control of the 2D monolayer organization through the thermodynamic parameters of PEDOT∙TMe-βCD and PEDOT∙TMe-γCD suggests potential for a wide range of optoelectronic applications.

Significance of Type II Collagen Posttranslational Modifications: From Autoantigenesis to Improved Diagnosis and Treatment of Rheumatoid Arthritis.

Collagen type II (COL2), the main structural protein of hyaline cartilage, is considerably affected by autoimmune responses associated with the pathogenesis of rheumatoid arthritis (RA). Posttranslational modifications (PTMs) play a significant role in the formation of the COL2 molecule and supramolecular fibril organization, and thus, support COL2 function, which is crucial for normal cartilage structure and physiology. Conversely, the specific PTMs of the protein (carbamylation, glycosylation, citrullination, oxidative modifications and others) have been implicated in RA autoimmunity. The discovery of the anti-citrullinated protein response in RA, which includes anti-citrullinated COL2 reactivity, has led to the development of improved diagnostic assays and classification criteria for the disease. The induction of immunological tolerance using modified COL2 peptides has been highlighted as a potentially effective strategy for RA therapy. Therefore, the aim of this review is to summarize the recent knowledge on COL2 posttranslational modifications with relevance to RA pathophysiology, diagnosis and treatment. The significance of COL2 PTMs as a source of neo-antigens that activate immunity leading to or sustaining RA autoimmunity is discussed.

Understanding the Rhodopsin Worldview Through Atomic Force Microscopy (AFM): Structure, Stability, and Activity Studies.

Rhodopsin is a G protein-coupled receptor (GPCR) present in the rod outer segment (ROS) of photoreceptor cells that initiates the phototransduction cascade required for scotopic vision. Due to the remarkable advancements in technological tools, the chemistry of rhodopsin has begun to unravel especially over the past few decades, but mostly at the ensemble scale. Atomic force microscopy (AFM) is a tool capable of providing critical information from a single-molecule point of view. In this regard, to bolster our understanding of rhodopsin at the nanoscale level, AFM-based imaging, force spectroscopy, and nano-indentation techniques were employed on ROS disc membranes containing rhodopsin, isolated from vertebrate species both in normal and diseased states. These AFM studies on samples from native retinal tissue have provided fundamental insights into the structure and function of rhodopsin under normal and dysfunctional states. We review here the findings from these AFM studies that provide important insights on the supramolecular organization of rhodopsin within the membrane and factors that contribute to this organization, the molecular interactions stabilizing the structure of the receptor and factors that can modify those interactions, and the mechanism underlying constitutive activity in the receptor that can cause disease.

Effects of Dispersed Carbon Nanotubes and Emerging Supramolecular Structures on Phase Transitions in Liquid Crystals: Physico-Chemical Aspects

The current state of the study of different liquid crystalline (LC) systems doped with carbon nanotubes (CNTs) is discussed. An attempt is endeavored to outline the state-of-the-art technology that has emerged after two past decades. Systematization and analysis are presented for the integration of single- and multi-walled carbon nanotubes in thermotropic (nematic, smectic, cholesteric, ferroelectric, etc.) and lyotropic LCs. Special attention is paid to the effects of alignment and supramolecular organization resulting from orientational coupling between CNTs and the LC matrix. The effects of the specific inter-molecular and inter-particle interactions and intriguing microstructural, electromagnetic, percolation, optical, and electro-optical properties are also discussed.

Dispersion in Crystal Structures of 1-Chloro-3-aryl-5-trihalomethyl-1λ4,2,4,6-thiatriazines: Towards an Understanding of the Supramolecular Organization of Covalent Thiazyl Chlorides

AbstractThe syntheses of five new 1-chloro-3-aryl-5-trichloromethyl-1λ4,2,4,6-thiatriazines, aryl = 4-R-C6H4- (R = CH3O, CH3, H, Cl and CF3), are reported with full characterization. Single-crystal X-ray diffraction structure determinations on all, as well as the 5-CF3 analogue which also has R = CF3, with models produced by Hirshfeld atom refinement, produced high-accuracy structures. All six exemplars form lateral dimers with short contacts that define a centrosymmetric {δ+S···Nδ−}2 motif, with interaction distances from 3.0473(9) to 3.422(3) Å, which do not vary in an expected manner with R. Normal population analysis charges computed by B3LYP-D3/6-311++G(d,p) DFT methods show small variations, and entirely as expected from the inductive effects of R. Gas-phase minimization of the dimers with M06-2X/aug-cc-pVDZ or B3LYP-D3/6-311++G(d,p) methods, with full counterpoise correction, replicate the experimental geometries for the 5-CF3, the 5-CCl3/CH3OC6H4 and the 5-CCl3/CH3C6H4 experimental structures, but diverge for other CCl3 exemplars. Interaction energies are more than double those computed for [(HC)2N2S]2. Using a geometry-optimized model with H in place of CX3, the interaction energy reduces to a very realistic –22 to –24 kJ/mol for just the {δ+S···Nδ−}2 motif, suggesting that CX3 interactions contribute 21% (CF3) to 37% (CCl3) of the total.

Development of the P-Arylation of Dithieno[3,2-b : 2',3'-d]phosphole with Aryl Iodonium Salts.

P-Arylation of dithieno[3,2-b : 2',3'-d]phosphole toward cationic phenyl phospholium species using diaryliodonium reagents was explored. Multiple conditions were tested to optimize the reaction, including variation of solvent, temperature, stoichiometry, time, and aryliodonium species employed. Initial use of diphenyliodonium chloride led to an unexpected dithienophosphole Cu(I) chloride complex that was characterized crystallographically. Alternatively, the use of diphenyliodonium hexafluorophosphate in ethanol under microwave conditions led to the successful isolation of the P-arylated target. The phenyl dithienophospholium species exhibits blue luminescence with a quantum yield of 100 % in solution that is considerably red-shifted in the solid state. The photophysics and solid-state organization of the new species were compared with those of a related methyl congener, showing distinct differences that are assigned to the nature of the carbon-based substituent at the phosphorus center, which was also confirmed by DFT calculations, and the supramolecular organization in the solid state.

A Comprehensive Analysis of the Intrinsic Visible Fluorescence Emitted by Peptide/Protein Amyloid-like Assemblies.

Amyloid aggregation is a widespread process that involves proteins and peptides with different molecular complexity and amino acid composition. The structural motif (cross-β) underlying this supramolecular organization generates aggregates endowed with special mechanical and spectroscopic properties with huge implications in biomedical and technological fields, including emerging precision medicine. The puzzling ability of these assemblies to emit intrinsic and label-free fluorescence in regions of the electromagnetic spectrum, such as visible and even infrared, usually considered to be forbidden in the polypeptide chain, has attracted interest for its many implications in both basic and applied science. Despite the interest in this phenomenon, the physical basis of its origin is still poorly understood. To gain a global view of the available information on this phenomenon, we here provide an exhaustive survey of the current literature in which original data on this fluorescence have been reported. The emitting systems have been classified in terms of their molecular complexity, amino acid composition, and physical state. Information about the wavelength of the radiation used for the excitation as well as the emission range/peak has also been retrieved. The data collected here provide a picture of the complexity of this multifaceted phenomenon that could be helpful for future studies aimed at defining its structural and electronic basis and/or stimulating new applications.

Protein ingredient quality of infant formulas impacts their structure and kinetics of proteolysis under in vitro dynamic digestion

Infant formula (IF) is a complex matrix requiring numerous ingredients and processing steps. The objective was to understand how the quality of protein ingredients impacts IF structure and, in turn, their kinetics of digestion. Four powdered IFs (A/B/C/D), based on commercial whey protein (WP) ingredients, with different protein denaturation levels and composition (A/B/C), and on caseins with different supramolecular organisations (C/D), were produced at a semi-industrial level after homogenization and spray-drying. Once reconstituted in water (13 %, wt/wt), the IF microstructure was analysed with asymmetrical flow field-flow fractionation coupled with multi-angle light scattering and differential refractometer, transmission electron microscopy and electrophoresis. The rehydrated IFs were subjected to simulated infant in vitro dynamic digestion (DIDGI®). Digesta were regularly sampled to follow structural changes (confocal microscopy, laser-light scattering) and proteolysis (OPA, SDS-PAGE, LC-MS/MS, cation-exchange chromatography). Before digestion, different microstructures were observed among IFs. IF-A, characterized by more denatured WPs, presented star-shaped mixed aggregates, with protein aggregates bounded to casein micelles, themselves adsorbed at the fat droplet interface. Non-micellar caseins, brought by non-micellar casein powder (IF-D) underwent rearrangement and aggregation at the interface of flocculated fat droplets, leading to a largely different microstructure of IF emulsion, with large aggregates of lipids and proteins. During digestion, IF-A more digested (degree of proteolysis + 16 %) at 180 min of intestinal phase than IF-C/D. The modification of the supramolecular organisation of caseins implied different kinetics of peptide release derived from caseins during the gastric phase (more abundant at G80 for IF-D). Bioactive peptide release kinetics were also different during digestion with IF-C presenting a maximal abundance for a large proportion of them. Overall, the present study highlights the importance of the structure and composition of the protein ingredients (WPs and caseins) selected for IF formulation on the final IF structure and, in turn, on proteolysis. Whether it has some physiological consequences remains to be investigated.

Structural insights into a unique PSI-LHCI-LHCII-Lhcb9 supercomplex from moss Physcomitrium patens.

Photosystem I (PSI) possesses a variable supramolecular organization among different photosynthetic organisms to adapt to different light environments. Mosses are evolutionary intermediates that diverged from aquatic green algae and evolved into land plants. The moss Physcomitrium patens (P. patens) has a light-harvesting complex (LHC) superfamily more diverse than those of green algae and higher plants. Here, we solved the structure of a PSI-LHCI-LHCII-Lhcb9 supercomplex from P. patens at 2.68 Å resolution using cryo-electron microscopy. This supercomplex contains one PSI-LHCI, one phosphorylated LHCII trimer, one moss-specific LHC protein, Lhcb9, and one additional LHCI belt with four Lhca subunits. The complete structure of PsaO was observed in the PSI core. One Lhcbm2 in the LHCII trimer interacts with PSI core through its phosphorylated N terminus, and Lhcb9 mediates assembly of the whole supercomplex. The complicated pigment arrangement provided important information for possible energy-transfer pathways from the peripheral antennae to the PSI core.