Unstable Membrane Research Articles

Long-term storage and intradermal vaccination of tumor-derived exosomes via sugar microneedles for improving tumor immunotherapies

Tumor-derived exosomes are gaining recognition as a promising cancer vaccine for immunotherapies due to their abundant tumor antigens and their role as endogenous carriers for antigen delivery. However, challenges including unstable membrane structures and compromised protein integrity during long-term storage, as well as the absence of effective delivery methods, restrict their clinical applications. Herein, we introduce an exosomes-loaded sugar microneedle (EXO-SMN) patch that not only allows for the long-term storage of exosomes but also facilitates intradermal delivery to enhance immunotherapies. By employing a two-casting micro-molding method, the EXO-SMN patch is composed of an array of tips simply made from trehalose, with a polyvinylpyrrolidone backing. The EXO-SMN patch demonstrates the capability to effectively protect the loaded exosomes, maintaining their membrane structure and protein integrity even after being stored at room temperature for at least one month. Additionally, the EXO-SMN patch possesses strong mechanical properties for skin penetration, facilitating the rapid release of exosomes into the skin within 120 s, and prolonging exosome retention in both skin and lymph nodes compared to intravenous (IV) or subcutaneous (SC) injections. Intradermal vaccination of tumor-derived exosomes via the EXO-SMN patch elicited higher antigen-specific immune responses and resulted in slower tumor growth compared to IV or SC injection. Given its easy to use and reliability, the proposed EXO-SMN patch could eventually facilitate the storage and delivery of exosomes in various biomedical applications.

Divergent folding-mediated epistasis among unstable membrane protein variants.

Many membrane proteins are prone to misfolding, which compromises their functional expression at the plasma membrane. This is particularly true for the mammalian gonadotropin-releasing hormone receptor GPCRs (GnRHR). We recently demonstrated that evolutionary GnRHR modifications appear to have coincided with adaptive changes in cotranslational folding efficiency. Though protein stability is known to shape evolution, it is unclear how cotranslational folding constraints modulate the synergistic, epistatic interactions between mutations. We therefore compared the pairwise interactions formed by mutations that disrupt the membrane topology (V276T) or tertiary structure (W107A) of GnRHR. Using deep mutational scanning, we evaluated how the plasma membrane expression of these variants is modified by hundreds of secondary mutations. An analysis of 251 mutants in three genetic backgrounds reveals that V276T and W107A form distinct epistatic interactions that depend on both the severity and the mechanism of destabilization. V276T forms predominantly negative epistatic interactions with destabilizing mutations in soluble loops. In contrast, W107A forms positive interactions with mutations in both loops and transmembrane domains that reflect the diminishing impacts of the destabilizing mutations in variants that are already unstable. These findings reveal how epistasis is remodeled by conformational defects in membrane proteins and in unstable proteins more generally.

Divergent folding-mediated epistasis among unstable membrane protein variants

Many membrane proteins are prone to misfolding, which compromises their functional expression at the plasma membrane. This is particularly true for the mammalian gonadotropin-releasing hormone receptor GPCRs (GnRHR). We recently demonstrated that evolutionary GnRHR modifications appear to have coincided with adaptive changes in cotranslational folding efficiency. Though protein stability is known to shape evolution, it is unclear how cotranslational folding constraints modulate the synergistic, epistatic interactions between mutations. We therefore compared the pairwise interactions formed by mutations that disrupt the membrane topology (V276T) or tertiary structure (W107A) of GnRHR. Using deep mutational scanning, we evaluated how the plasma membrane expression of these variants is modified by hundreds of secondary mutations. An analysis of 251 mutants in three genetic backgrounds reveals that V276T and W107A form distinct epistatic interactions that depend on both the severity and the mechanism of destabilization. V276T forms predominantly negative epistatic interactions with destabilizing mutations in soluble loops. In contrast, W107A forms positive interactions with mutations in both loops and transmembrane domains that reflect the diminishing impacts of the destabilizing mutations in variants that are already unstable. These findings reveal how epistasis is remodeled by conformational defects in membrane proteins and in unstable proteins more generally.

Mechanistic insights into different illumination positions control algae production in anaerobic dynamic membrane filtration (AnDM) during decentralized wastewater treatment

Sunlight illumination has the potential to control the stability and sustainability of dynamic membrane (DM) systems. In this study, an up-flow anaerobic sludge blanket (UASB) reactor was combined with DM under different illumination positions (direct, indirect and no illumination) to treat wastewater. Results indicated that the UASB achieved a COD removal up to 87.05 % with an average methane production of 0.28 L/d. Following treatment by the UASB, it was found that under illumination, the removal of organic substances by DM exhibited poor performance due to algal proliferation. However, the DM systems demonstrated efficient removal of ammonia nitrogen, ranging from 96.21 % to 97.67 % after stabilization. Total phosphorus removal was 45.72 %, and membrane flux remained stable when directly illuminated. Conversely, the DM system subjected to indirect illumination showed unstable membrane flux and severe fouling resistance. These findings offer valuable insights into optimizing illumination positions in DM systems under anaerobic conditions.

The Exploitation of Lysosomes in Cancer Therapy with Graphene-Based Nanomaterials.

Graphene-based nanomaterials (GNMs), including graphene, graphene oxide, reduced graphene oxide, and graphene quantum dots, may have direct anticancer activity or be used as nanocarriers for antitumor drugs. GNMs usually enter tumor cells by endocytosis and can accumulate in lysosomes. This accumulation prevents drugs bound to GNMs from reaching their targets, suppressing their anticancer effects. A number of chemical modifications are made to GNMs to facilitate the separation of anticancer drugs from GNMs at low lysosomal pH and to enable the lysosomal escape of drugs. Lysosomal escape may be associated with oxidative stress, permeabilization of the unstable membrane of cancer cell lysosomes, release of lysosomal enzymes into the cytoplasm, and cell death. GNMs can prevent or stimulate tumor cell death by inducing protective autophagy or suppressing autolysosomal degradation, respectively. Furthermore, because GNMs prevent bound fluorescent agents from emitting light, their separation in lysosomes may enable tumor cell identification and therapy monitoring. In this review, we explain how the characteristics of the lysosomal microenvironment and the unique features of tumor cell lysosomes can be exploited for GNM-based cancer therapy.

Modelling and testing of a pressure-differential wave energy converter with flexible membranes

We investigate a wave energy converter composed of two submerged, bottom-fixed air-filled cylindrical chambers, separated by a distance of ideally half a wavelength, and closed on top by flexible membranes. A passing wave creates a pressure differential between the two chambers which drives the membranes and causes air to flow through a turbine. Using linear analysis and physical model testing, we show that the device exhibits broad-banded power absorption. Our linear model successfully predicts the pressure differential and absorbed power measured in the tests, except at low frequencies, where the differences are attributed to unstable membrane conditions due to a negative total stiffness. Using a simple model, we show that the flat-membrane equilibrium, in the absence of additional stiffness, is unstable. By introducing an additional stiffness to the membrane, this instability can be avoided and the natural period of the device can theoretically be tuned to any value. With a matching flow resistance, it is possible to attain absorbed power values close to the theoretical limit.

Yeast-based directed-evolution for high-throughput structural stabilization of G protein-coupled receptors (GPCRs)

The immense potential of G protein-coupled receptors (GPCRs) as targets for drug discovery is not fully realized due to the enormous difficulties associated with structure elucidation of these profoundly unstable membrane proteins. The existing methods of GPCR stability-engineering are cumbersome and low-throughput; in addition, the scope of GPCRs that could benefit from these techniques is limited. Here, we present a yeast-based screening platform for a single-step isolation of GRCR variants stable in the presence of short-chain detergents, a feature essential for their successful crystallization using vapor diffusion method. The yeast detergent-resistant cell wall presents a unique opportunity for compartmentalization, to physically link the receptor's phenotype to its encoding DNA, and thus enable discovery of stable GPCR variants with unprecedent efficiency. The scope of mutations identified by the method reveals a surprising amenability of the GPCR scaffold to stabilization, and suggests an intriguing possibility of amending the stability properties of GPCR by varying the structural status of the C-terminus.

Enabling NMR Studies of High Molecular Weight Systems Without the Need for Deuteration: The XL‐ALSOFAST Experiment with Delayed Decoupling

Current biological research increasingly focusses on large human proteins and their complexes. Such proteins are difficult to study by NMR spectroscopy because they often can only be produced in higher eukaryotic expression systems, where deuteration is hardly feasible. Here, we present the XL‐ALSOFAST‐[13C,1H]‐HMQC experiment with much improved sensitivity for fully protonated high molecular weight proteins. For the tested systems ranging from 100 to 240 kDa in size, 3‐fold higher sensitivity was obtained on average for fast relaxing signals compared to current state‐of‐the‐art experiments. In the XL‐ALSOFAST approach, non‐observed magnetisation is optimally exploited and transverse relaxation is minimized by the newly introduced concept of delayed decoupling. The combination of high sensitivity and superior artefact suppression makes it ideal for studying inherently unstable membrane proteins or for analysing therapeutic antibodies at natural 13C abundance. The XL‐ALSOFAST and delayed decoupling will therefore expand the range of biomolecular systems accessible to NMR spectroscopy.

Plasticity of sympathetic post‐ganglionic neuron after spinal cord injury

Autonomic dysreflexia (AD) is a hypertensive crisis seen in high‐thoracic spinal cord injured (ht‐SCI) patients normally triggered by noxious stimuli below the injury level. Previous animal research on mechanisms underlying AD have mostly focused on neural plasticity within the injured spinal cord. No studies have assessed whether there is also plasticity in the sympathetic post‐ganglionic neurons (SPNs) ‐ the final neural element responsible for vasoconstriction.Thoracic sympathetic post‐ganglionic neurons (tSPNs) are located in paravertebral ganglia and provide the dominant sympathetic control of blood pressure. Their cellular properties are understudied. The few previous ex vivo studies used sharp electrodes that likely leads to significant impalement injury‐induced changes [1, 2]. We undertook whole‐cell patch clamp recordings in an adult mouse tSPN ex vivo preparation. Compared to earlier reports using sharp electrodes, we observed an order of magnitude greater passive membrane properties (cell resistance and membrane time constant) and repetitive rather than phasic firing properties. Together these observations support much greater excitability and integrative actions of tSPNs than previously assumed.Using the same methodology we then studied whether these neurons undergo plastic changes after high‐thoracic (T2) spinal cord transection (ht‐SCI), an animal model of AD. Recordings were obtained from T3‐T9 tSPNs at 3 weeks and 6 weeks post injury. Preliminary data suggest that early after injury (3 weeks), tSPNs are hypo‐active compared to normal animal, including more hyperpolarized resting membrane potential and higher rheobase and threshold voltage. At 6 weeks post‐SCI, tSPN passive membrane properties are similar to control mice. However, several neurons show spontaneously unstable membrane potential (55% of recorded neurons), which is rarely seen in control. Evidences that tSPNs may become more excitable include lower rheobase and threshold voltage values on average and an increased incidence of nifedipine sensitive persistent inward currents (PIC; 69% of recorded neurons after SCI has PIC comparing to 22% in control). Also, tSPNs appear to receive more frequent spontaneous cholinergic synaptic input after SCI.Support or Funding InformationThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Recombinant expression of extracellular domain of mutant Epidermal Growth Factor Receptor in prokaryotic and baculovirus expression systems

Epidermal Growth Factor Receptor variant III (EGFRvIII) is a tumor specific antigen detected in various tumors including gliomas, breast cancer, lung cancer, head and neck squamous cell carcinoma (HNSCC). Screening of EGFRvIII targeting drug molecules can be accelerated by developing drug screening platforms using recombinantly expressed protein. Choice of expression system is one of the major factors deciding the success of recombinant expression of a protein. In our study, we have tried to express and purify the extracellular domain (ECD) of this highly unstable protein using bacterial and baculovirus expression systems to select the expression system suited for our purpose. Even though the protein was successfully expressed in prokaryotic system, purification could be done only under denaturing conditions. But in the baculovirus expression system, the protein was expressed in soluble form and could be purified under native conditions, with single step of purification. Based on our results, we conclude that insect cells are better choice over E. coli cells for expressing EGFRvIII ECD in soluble form. This study provides insights for other researchers involved in expression of similar unstable membrane proteins, on selecting the best expression system and challenges involved.

SO2 interference on separation performance of amine-containing facilitated transport membranes for CO2 capture from flue gas

Post-combustion carbon capture using membranes is a key approach to control CO2 emissions from power plants using fossil fuels. The minor contaminants, such as SO2 and O2, may influence the long-term membrane performance. With the presence of SO2 in the feed gas, SO2 could preferably react with amine carriers and hinder the permeation of CO2 in the amine-containing facilitated transport membranes. Possible amine degradation and competitive reactions would reduce membrane performance with real flue gas. With SO2 concentrations of 0.7–5ppm, two amine-containing facilitated transport membranes were tested at 57 and 102°C, respectively. Unstable membrane performance was observed at 102°C for the membrane containing Lupamin® as fixed-site carrier and potassium glycinate (K-Gly) as mobile carrier in the presence of SO2. On the contrary, two membranes containing polyvinylamine (PVAm) as fixed-site carrier and amino acid salts as mobile carriers showed stable separation performance in the presence of 1–3ppm SO2 at 57°C. Therefore, the operating temperature plays a significant role in the membrane stabilities in the presence of SO2. In addition, the infrared (IR) spectra of the membrane components exposed to SO2 with respect to exposure time were collected. It was found that the amines reacted with SO2 to form sulfite products irreversibly at 102°C. The spectral results were consistent with the observed membrane separation performance. The stable membrane performances of the facilitated transport membranes at 57°C with SO2 at ppm levels indicate the applicability of the developed amine-containing membranes for use in CO2 capture from real flue gas.

Antigenic Peptide Recognition on the Human ABC Transporter TAP Resolved by DNP-Enhanced Solid-State NMR Spectroscopy.

The human transporter associated with antigen processing (TAP) is a 150 kDa heterodimeric ABC transport complex that selects peptides for export into the endoplasmic reticulum and subsequent loading onto major histocompatibility complex class I molecules to trigger adaptive immune responses against virally or malignantly transformed cells. To date, no atomic-resolution information on peptide-TAP interactions has been obtained, hampering a mechanistic understanding of the early steps of substrate translocation catalyzed by TAP. Here, we developed a mild method to concentrate an unstable membrane protein complex and combined this effort with dynamic nuclear polarization enhanced magic angle spinning solid-state NMR to study this challenging membrane protein-substrate complex. We were able to determine the atomic-resolution backbone conformation of an antigenic peptide bound to human TAP. Our NMR data also provide unparalleled insights into the nature of the interactions between the side chains of the antigen peptide and TAP. By combining NMR data and molecular modeling, the location of the peptide binding cavity has been identified, revealing a complex scenario of peptide-TAP recognition. Our findings reveal a structural and chemical basis of substrate selection rules, which define the crucial function of this ABC transporter in human immunity and health. This work is the first NMR study of a eukaryotic transporter protein and presents the power of solid-state NMR in this growing field.

Identification of suitable combinations of in vitro sperm-function test for the prediction of fertility in buffalo bull

The present study assessed sperm functional characteristics in the frozen-thawed semen of buffalo bulls and estimated their relationship with field fertility. Frozen semen samples from three different freezing operations each from nine Murrah buffalo bulls were used for the assessment of different sperm functions related to fertilizing potential. Bulls were classified into high (n = 2), medium (n = 5), and low (n = 2) fertile based on adjusted field fertility. The sperm functions estimated included membrane integrity using carboxyfluorescein diacetate-propidium iodide, acrosome reaction status using fluorescein isothiocyanate peanut agglutinine, status of apoptosis using Annexin-V, protamine deficiency using Chromomycin A3, membrane stability using Merocyanine 540 and lipid peroxidation status using 4, 4-difluoro-4-bora-3a, 4a-diaza-s-indacene. The relationship between the proportion of live acrosome-intact spermatozoa and fertility was positive and significant (r = 0.59; P = 0.001). The proportion of moribund spermatozoa showed a significantly negative correlation with fertility (r = −0.50; P = 0.008). Similarly, the relationship of spermatozoa with unstable membrane (r = −0.51; P = 0.007), necrotic (r = − 0.42; P = 0.028), early necrotic (r = −0.42; P = 0.031), and apoptotic spermatozoa (r = −0.39; P = 0.046) with bull fertility was negative and significant. The correlation between the protamine-deficient spermatozoa and fertility was negative, but not significant. Among different combinations of tests, live acrosome-intact spermatozoa and lipid peroxidation status of spermatozoa revealed high positive correlation with buffalo bull fertility (adjusted R2 = 0.73, C[p] = 0.80). These preliminary findings may help in developing tools for assessing fertility of buffalo bulls, once validated in more animals.

An Unstable Two-Phase Membrane Problem and Maximum Flux Exchange Flow

Let U be a bounded open connected set in mathbb {R}^n (nge 1). We refer to the unique weak solution of the Poisson problem -Delta u = chi _A on U with Dirichlet boundary conditions as u_A for any measurable set A in U. The function psi :=u_U is the torsion function of U. Let V be the measure V:=psi ,mathscr {L}^n on U where mathscr {L}^n stands for n-dimensional Lebesgue measure. We study the variational problem I(U,p):=sup{J(A)-V(U)p2}\\documentclass[12pt]{minimal}\t\t\t\t\\usepackage{amsmath}\t\t\t\t\\usepackage{wasysym}\t\t\t\t\\usepackage{amsfonts}\t\t\t\t\\usepackage{amssymb}\t\t\t\t\\usepackage{amsbsy}\t\t\t\t\\usepackage{mathrsfs}\t\t\t\t\\usepackage{upgreek}\t\t\t\t\\setlength{\\oddsidemargin}{-69pt}\t\t\t\t\\begin{document}$$\\begin{aligned} I(U,p):=\\sup \\Big \\{ J(A)-V(U)\\,p^2\\,\\Big \\} \\end{aligned}$$\\end{document}with pin (0,1) where J(A):=int _Au_A,dx and the supremum is taken over measurable sets Asubset U subject to the constraint V(A)=pV(U). We relate the above problem to an unstable two-phase membrane problem. We characterise optimsers in the case n=1. The proof makes use of weighted isoperimetric and Pólya–Szegö inequalities.

Linking lipid architecture to bilayer structure and mechanics using self-consistent field modelling

To understand how lipid architecture determines the lipid bilayer structure and its mechanics, we implement a molecularly detailed model that uses the self-consistent field theory. This numerical model accurately predicts parameters such as Helfrichs mean and Gaussian bending modulus kc and k̄ and the preferred monolayer curvature J(0)(m), and also delivers structural membrane properties like the core thickness, and head group position and orientation. We studied how these mechanical parameters vary with system variations, such as lipid tail length, membrane composition, and those parameters that control the lipid tail and head group solvent quality. For the membrane composition, negatively charged phosphatidylglycerol (PG) or zwitterionic, phosphatidylcholine (PC), and -ethanolamine (PE) lipids were used. In line with experimental findings, we find that the values of kc and the area compression modulus kA are always positive. They respond similarly to parameters that affect the core thickness, but differently to parameters that affect the head group properties. We found that the trends for k̄ and J(0)(m) can be rationalised by the concept of Israelachivili's surfactant packing parameter, and that both k̄ and J(0)(m) change sign with relevant parameter changes. Although typically k̄ < 0, membranes can form stable cubic phases when the Gaussian bending modulus becomes positive, which occurs with membranes composed of PC lipids with long tails. Similarly, negative monolayer curvatures appear when a small head group such as PE is combined with long lipid tails, which hints towards the stability of inverse hexagonal phases at the cost of the bilayer topology. To prevent the destabilisation of bilayers, PG lipids can be mixed into these PC or PE lipid membranes. Progressive loading of bilayers with PG lipids lead to highly charged membranes, resulting in J(0)(m) >> 0, especially at low ionic strengths. We anticipate that these changes lead to unstable membranes as these become vulnerable to pore formation or disintegration into lipid disks.

The Sensing of Membrane Microdomains Based on Pore-Forming Toxins

Membrane rafts are transient and unstable membrane microdomains that are enriched in sphingolipids, cholesterol, and specific proteins. They are involved in intracellular trafficking, signal transduction, pathogen entry, and attachment of various ligands. Increasing experimental evidence on the crucial biological roles of membrane rafts under normal and pathological conditions require new techniques for their structural and functional characterization. In particular, fluorescence-labeled cytolytic proteins that interact specifically with molecules enriched in rafts are of increasing interest. Cholera toxin subunit B interacts specifically with raft-residing ganglioside G(M1), and it has long been the lipid probe of choice for membrane rafts. Recently, four new pore-forming toxins have been proposed as selective raft markers: (i) equinatoxin II, a cytolysin from the sea anemone Actinia equina, which specifically recognizes free and membrane-embedded sphingomyelin; (ii) a truncated non-toxic mutant of a cytolytic protein, lysenin, from the earthworm Eisenia foetida, which specifically recognizes sphingomyelin-enriched membrane domains; (iii) a non-toxic derivative of the cholesterol-dependent cytolysin perfringolysin O, from the bacterium Clostridium perfringens, which selectively binds to membrane domains enriched in cholesterol; and (iv) ostreolysin, from the mushroom Pleurotus ostreatus, which does not bind to a single raft-enriched lipid component, but requires a specific combination of two of the most important raft-residing lipids: sphingomyelin and cholesterol. Nontoxic, raft-binding derivatives of cytolytic proteins have already been successfully used to explore both the structure and function of membrane rafts, and of raft-associated molecules. Here, we review these four new derivatives of pore-forming toxins as new putative markers of these membrane microdomains.

ChemInform Abstract: Designer Peptide Surfactants Stabilize Diverse Functional Membrane Proteins

AbstractReview: 36 refs.

Computer Simulation on the Cooperation of Functional Molecules during the Early Stages of Evolution

It is very likely that life began with some RNA (or RNA-like) molecules, self-replicating by base-pairing and exhibiting enzyme-like functions that favored the self-replication. Different functional molecules may have emerged by favoring their own self-replication at different aspects. Then, a direct route towards complexity/efficiency may have been through the coexistence/cooperation of these molecules. However, the likelihood of this route remains quite unclear, especially because the molecules would be competing for limited common resources. By computer simulation using a Monte-Carlo model (with “micro-resolution” at the level of nucleotides and membrane components), we show that the coexistence/cooperation of these molecules can occur naturally, both in a naked form and in a protocell form. The results of the computer simulation also lead to quite a few deductions concerning the environment and history in the scenario. First, a naked stage (with functional molecules catalyzing template-replication and metabolism) may have occurred early in evolution but required high concentration and limited dispersal of the system (e.g., on some mineral surface); the emergence of protocells enabled a “habitat-shift” into bulk water. Second, the protocell stage started with a substage of “pseudo-protocells”, with functional molecules catalyzing template-replication and metabolism, but still missing the function involved in the synthesis of membrane components, the emergence of which would lead to a subsequent “true-protocell” substage. Third, the initial unstable membrane, composed of prebiotically available fatty acids, should have been superseded quite early by a more stable membrane (e.g., composed of phospholipids, like modern cells). Additionally, the membrane-takeover probably occurred at the transition of the two substages of the protocells. The scenario described in the present study should correspond to an episode in early evolution, after the emergence of single “genes”, but before the appearance of a “chromosome” with linked genes.

Noninvasive Detection of Spontaneous Muscle Activity in Amyotrophic Lateral Sclerosis in Frequency Domain

Changes in Calcium ion balance in muscle fraction has been connected to occurrence of spontaneous bioelectrical activities. These changes would result in an unstable membrane potential and therefore, involuntary action potentials start to fire on individual single muscle fibers, called fibrillation potentials. Evidence of fibrillation potentials is a hallmark of muscular degenerative diseases, such as Amyotrophic Lateral Sclerosis (ALS). Detection of fibrillation potentials is typically done by inserting needle electrodes. However, there are some uncertainties, reported by some studies with regard to origins of detected fibrillation potentials, suggesting that these oscillatory potentials could be an artifact of needle insertion and a result of muscle fibers injured by the needle. In this work, baseline electromyographic (EMG) signals from control subjects and subjects with ALS are compared. The signals are recorded non-invasively using high-density surface EMG electrodes. The data are analyzed in frequency domain, since fibrillation potentials are not detectable on surface EMG in time domain. Significant differences at some frequency bands are observed, and different underlying reasons are discussed.

Designer peptidesurfactants stabilize diverse functional membrane proteins

Multi-spanning integral membrane proteins, including G-protein coupled receptors (GPCR), ion channels, and ion transporters, comprise a major class of drug targets. However, despite their vital importance, most molecular structures of membrane proteins remain elusive. This is largely due to lack of effective materials and methods to stabilize their functional conformation for sufficient time. Thus finding optimal surfactants and developing new approaches to study fundamental properties of unstable membrane proteins is urgently needed. In this tutorial review we summarize designer peptides with surfactant properties and their usefulness to stabilize membrane proteins. These peptide surfactants present new opportunities for the stabilization and characterization of diverse membrane proteins. Previous studies on the interaction between surfactant peptides and membrane proteins revealed strategies to design new peptides tailor-made for the stabilization of specific proteins. We review examples of solubilization, purification, long-term stabilization of membrane proteins, and the design principles of peptide sequences. We discuss future trends for exploiting spatial features, thermodynamic parameters, and self-assembling properties to create peptide surfactant structures to facilitate the characterization of diverse membrane proteins.