{"title":"Crystallographic binding modes of octahedral transition metal complexes to duplex DNA.","authors":"Tayler D Prieto Otoya, Christine Janet Cardin","doi":"10.1017/S0033583526100122","DOIUrl":"10.1017/S0033583526100122","url":null,"abstract":"<p><p>Octahedral transition metal complexes are increasingly recognised as useful tools for the development of complex cations that recognise and interact with specific DNA sequences and higher-order DNA topologies. The versatility and diversity of these complexes is particularly due to their rich photophysical and electrochemical properties at the octahedral metal centre, which can be modulated by changing the surrounding ligands. While X-ray crystallography provides uniquely direct structural information on metal-DNA binding, it is one of several essential approaches; solution-state methods such as NMR and complementary biophysical studies are critical for defining predominant binding modes in solution and in biologically relevant environments. Here, we present an overview of the different binding modes of some of these octahedral transition metal complexes with DNA, emphasising the structural and biophysical studies employed to understand metal complex-DNA interactions.</p>","PeriodicalId":20828,"journal":{"name":"Quarterly Reviews of Biophysics","volume":"59 ","pages":"e4"},"PeriodicalIF":6.1,"publicationDate":"2026-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147575258","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Cryo-EM of endogenous membrane proteins in their native lipid bilayer.","authors":"John L Rubinstein","doi":"10.1017/S0033583526100109","DOIUrl":"10.1017/S0033583526100109","url":null,"abstract":"<p><p>Single-particle electron cryomicroscopy (cryo-EM) has enabled rapid advances in our understanding of membrane protein structure and function. The primary goal during the development of cryo-EM was to perform experiments equivalent to X-ray crystallography, but without needing to crystallize the protein of interest first. However, exciting recent progress in single-particle cryo-EM has come from relaxing assumptions and constraints related to the homogeneity of samples. These assumptions and constraints, which were necessary for crystallization, include that all molecules imaged have the same composition and are in the same conformation, that the specimen consists of only one species, and that the specimen is derived from a solution of isolated protein particles. Here, I discuss the study of membrane protein complexes within lipid bilayers by single-particle cryo-EM. I point out the value and recently achieved capability of studying membrane proteins in lipid vesicles, and in particular endogenous membrane proteins in vesicles prepared from their native lipid bilayer.</p>","PeriodicalId":20828,"journal":{"name":"Quarterly Reviews of Biophysics","volume":"59 ","pages":"e3"},"PeriodicalIF":6.1,"publicationDate":"2026-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147366418","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Julien Roche, Christian Roumestand, Catherine A Royer
{"title":"Revealing protein dynamics with high-pressure NMR.","authors":"Julien Roche, Christian Roumestand, Catherine A Royer","doi":"10.1017/S0033583526100092","DOIUrl":"https://doi.org/10.1017/S0033583526100092","url":null,"abstract":"<p><p>While the structure of proteins can now be predicted from sequence with high certainty, the prediction of protein functional dynamics remains to be achieved. Progress towards this goal will require a much larger experimental database of the relationships among sequence, dynamics, and function than currently available. Dynamic transitions that are key to protein function and turnover remain difficult to access and characterize because they have significantly higher free energy than the folded states of proteins and hence are not populated. To access these higher free energy states, proteins must be perturbed. High temperatures often lead to aggregation, while chemical denaturants, because they interact with the entire protein backbone, tend to smooth protein conformational landscapes. In contrast, high hydrostatic pressure represents a continuous and reversible variable that can perturb protein structure locally around internal cavities, leading to partial structural disruption, populating these higher energy states sufficiently for their characterization.</p>","PeriodicalId":20828,"journal":{"name":"Quarterly Reviews of Biophysics","volume":"59 ","pages":"e2"},"PeriodicalIF":5.3,"publicationDate":"2026-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147309514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The energy barrier model in membrane biophysics: Ion flow, current-voltage relations, and Donnan osmosis.","authors":"Gerald Manning","doi":"10.1017/S0033583526100110","DOIUrl":"10.1017/S0033583526100110","url":null,"abstract":"<p><p>Theoretical analysis of an energy barrier model for the electrical properties of a biological membrane yields new results. Discontinuities at the membrane-solution interfaces are crucial and receive careful attention, as does the polarization charge density due to electroneutral but polarized ion distributions. The topics explored include the equilibrium and time-dependent Nernst potential, the resting potential, the capacitance-resistance equation for membrane voltage, and large electrical effects on osmosis (bulk volume flow). The generalization of Nernst-Hartley salt diffusion to the diffusion of mixed salts as a necessary tool is accomplished. The electric field inside the membrane is especially strong at the membrane-solution interfaces. The analysis of the resting potential differs from the Goldman-Hodgkin-Katz formulation but predicts realistic numerical values for animal cells and also captures the effect of switching sodium and potassium ion permeabilities. An analysis of the physical basis of bulk water flow in the presence of impermeant and permeant ions, that is, Donnan osmosis, reveals large ion charge effects that have not previously been considered. The equation derived here for Donnan osmotic flow helps to explain why the action of the sodium pump is essential for the prevention of excessive osmotic stress on cellular membranes.</p>","PeriodicalId":20828,"journal":{"name":"Quarterly Reviews of Biophysics","volume":"59 ","pages":"e1"},"PeriodicalIF":6.1,"publicationDate":"2026-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147284876","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The multifaceted character of water as solvent for proteins: From poor for folded proteins to good for (some) intrinsically disordered proteins and protein segments.","authors":"Reinhard Schweitzer-Stenner","doi":"10.1017/S0033583526100080","DOIUrl":"10.1017/S0033583526100080","url":null,"abstract":"<p><p>Intrinsically disordered proteins (IDPs) and disordered regions of folded proteins (IDRs) perform a plethora of cellular functions involving interactions with a variety of proteins, DNA, and RNA. Their flexibility enables them to interact with different cellular components. They can adopt molten globule as well as extended statistical coil structures depending on their amino acid residue sequence. They are generally more enriched in polar and charged residues, which generally facilitate solvation. This review article asks to what extent water as a solvent affects local (on a residue level) and global properties (size, Flory exponents) of IDPs. It introduces various aspects of protein hydration in the folded state as a benchmark and reference. The results of experimental and computational studies on short model peptides reveal how local structural propensities of residues are determined by water-backbone and water-side chain interactions. Ramachandran plots of individual amino acid residues are side-chain and neighbor-dependent. For unfolded oligo-peptides and IDPs (IDRs) the article discusses the intricated relationship between IDP hydration and global parameters (i.e., radius of gyration), which involves multiple parameters such as net charge, charge distribution, hydrophobicity, and the ionic strength of the aqueous solution. A review of experimental work that explored the strength of water-protein interactions and their influence on water dynamics reveals significant differences between water binding to folded and disordered proteins. Finally, The role of water in liquid-liquid mixing of short peptides and IDPs is delineated, which can lead to gelation and the formation of membrane-less droplets.</p>","PeriodicalId":20828,"journal":{"name":"Quarterly Reviews of Biophysics","volume":" ","pages":"e5"},"PeriodicalIF":6.1,"publicationDate":"2026-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147271882","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Delivery of macromolecular drugs: An update.","authors":"Robert Langer","doi":"10.1017/S0033583525100073","DOIUrl":"10.1017/S0033583525100073","url":null,"abstract":"<p><p>In 2019, in this journal, I discussed approaches for controlling the movement of molecules, in particular macromolecules, with an emphasis on how this enabled advances in the field of drug delivery - a field that has impacted billions of people worldwide. Since 2019, there have been advances in our work and this field including a striking demonstration in which drug delivery nanoparticles were crucial to the success of mRNA therapies and the Covid-19 vaccine. In this paper, I provide updates in such areas as i) developing new methods for oral drug delivery systems, ii) delivery of molecules to specific sites of the body, iii) new types of delivery systems, and iv) examples of machine learning/artificial intelligence in these areas. I also discuss advances in mRNA technology as it relates to drug delivery and the development of nanoparticles to protect and deliver vaccines, which saved and improved the lives of hundreds of millions of people throughout the world.</p>","PeriodicalId":20828,"journal":{"name":"Quarterly Reviews of Biophysics","volume":" ","pages":"e19"},"PeriodicalIF":5.3,"publicationDate":"2025-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145542176","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Allostery: allosteric networks and allosteric signaling bias.","authors":"Ruth Nussinov, Bengi R Yavuz, Hyunbum Jang","doi":"10.1017/S0033583525100061","DOIUrl":"10.1017/S0033583525100061","url":null,"abstract":"<p><p>Allosteric communication is established by networks through which strain energy generated at the allosteric site by an allosteric event, such as ligand binding, can propagate to the functional site. Exerted on multiple molecules in the cell, it can wield a biased function. Here, we discuss <i>allosteric networks</i> and <i>allosteric signaling bias. Networks</i> are graphs specified by nodes (residues) and edges (their connections). Allosteric <i>bias</i> is a property of a population. It is described by allosteric effector-specific dynamic distributions of conformational ensembles, as classically exemplified by G protein-coupled receptors (GPCRs). An ensemble describes the <i>likelihood</i> of a specific (strong/weak) allosteric signal propagating to a specific functional site. A network description provides the propagation route in a specific conformation, pinpointing key residues whose mutations could promote drug resistance. Efficiency is influenced by path length, relative stabilities and allosteric transitions. Through specific contacts, specific ligands can bias signaling in proteins, for example, in receptor tyrosine kinases (RTKs) toward specific phosphorylation sites and cell signaling activation. Thus, rather than the two - active and inactive - states, and a single pathway, we consider multiple states and favored pathways. This allows us to consider <i>biased allosteric switches among minor, invisible states and observable outcomes.</i> Within this framework, we further consider signaling strength and duration as key determinants of cell fate: <i>If w</i>eak and sustained, it may induce differentiation; <i>If</i> bursts of strong and short, proliferation.</p>","PeriodicalId":20828,"journal":{"name":"Quarterly Reviews of Biophysics","volume":" ","pages":"e17"},"PeriodicalIF":5.3,"publicationDate":"2025-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145542113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Time-resolved fluorescence of tryptophan in biophysical chemistry and pharmaceutical research - the pleasures and nightmares dealing with nature's own fluorophore.","authors":"Iulia Carabadjac, Heiko Heerklotz","doi":"10.1017/S003358352510005X","DOIUrl":"10.1017/S003358352510005X","url":null,"abstract":"<p><p>Time-resolved (TR) intrinsic fluorescence of tryptophan (Trp) provides a wealth of information on the structure and localization of proteins and peptides and their interactions with one another, with drugs, lipid membranes, lipid- and surfactant-based drug delivery systems, et cetera. Intrinsic Trp eliminates the need for labeling and avoids the perturbation of the system by the label; introduced Trp is a rather conservative and small label compared to others. Whereas custom-tailored fluorophores are often optimized for a special technique, Trp can be employed to monitor a wide variety of effects. We address interactions of Trp with surrounding molecules, dynamic quenchers and Förster resonance energy transfer (FRET) acceptors that affect the fluorescence decay. Speed and range of angular motion of Trp are characterized by TR anisotropy. Electrostatic interactions of Trp with charged and polar molecules, including water, are monitored by decay-associated spectra (DAS) or TR emission spectra (TRES) and quantified in terms of TR shifts of the spectral center of gravity. This versatility is a great advantage and, at the same time, comes with a complexity of the behavior that can render it a challenge to interpret the data in detail properly. This review provides an overview of applications of TR fluorescence of Trp bulk samples in biomolecular, biophysical, and pharmaceutical studies. The aim is not only to point out the diversity of the read-out of these techniques, but also critically examine their current use. Therefore, we identify most common technical pitfalls and evaluate the degree of reliability of the interpretational approaches. This should aid a more extensive and meaningful use of TR fluorescence of Trp.</p>","PeriodicalId":20828,"journal":{"name":"Quarterly Reviews of Biophysics","volume":" ","pages":"e18"},"PeriodicalIF":5.3,"publicationDate":"2025-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145431828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Resilience of DNA chains to molecular fracture after PCR heating cycles and implications on PCR reliability - EXPRESSION OF CONCERN.","authors":"Roberto Serpieri, Fabio Franchi","doi":"10.1017/S0033583525100036","DOIUrl":"10.1017/S0033583525100036","url":null,"abstract":"","PeriodicalId":20828,"journal":{"name":"Quarterly Reviews of Biophysics","volume":"58 ","pages":"e16"},"PeriodicalIF":5.3,"publicationDate":"2025-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144776019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"How reliable is PCR? A mini review.","authors":"Helen Konrad, Andreas Beyer","doi":"10.1017/S0033583525100024","DOIUrl":"10.1017/S0033583525100024","url":null,"abstract":"<p><p>The question of whether PCR is reliable sounds strange at first. However, looking at the scientific literature from the 1950s and 60s, one will find many publications on the physicochemistry of DNA that have been forgotten meanwhile. Quite a few of these studies have shown that DNA is thermolabile, which consequently raises the question of whether this thermolability is relevant in the context of PCR, namely in the denaturation phase. However, it can be shown that this is not the case: losses due to thermal hydrolysis are irrelevant for the performance of contemporary PCR protocols and their specificity as well as for the significance of their results. There is now a huge amount of scientifically verified and published data on technical and molecular aspects of PCR, a small selection of which we quote here. In addition, we present some primary data that also clearly demonstrate the reliability of PCR.</p>","PeriodicalId":20828,"journal":{"name":"Quarterly Reviews of Biophysics","volume":"58 ","pages":"e15"},"PeriodicalIF":5.3,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144601316","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}