Structure Of Keratin Research Articles

Herbs in Cosmetics: An Overview

Cosmetics are widely used by both men and women for beauty enhancement for ages. Herbal plants have been used in cosmetics manufacturing for centuries because they constitute natural ingredients that are harmless. Cosmetics alone are not capable to manage both beauty enhancement and skin care. Hence, herbs are used because they are able to check skin damage and aging due to the presence of natural constituents. Herbal cosmetics have gained immense popularity among the population because they do not show side effects as shown by synthetic cosmetics. The inclusion of herbal extracts in cosmetics can minimize skin damage due to oxidative stress and thus aging process gets delayed. Herbal products improve various functions of skin by boosting collagen growth and thus eradicating harmful effects of free radicals, maintaining the structure of keratin, and keeping skin healthy. A number of herbal plants are naturally accessible and are used in the preparation of herbal cosmetics. These include gingko, neem, coconut, and many more. Herbal cosmetics for daily purposes include lotion, creams, oils, cleansers, etc. Herbal skin cosmetics have multi functionalities like anti-oxidant, anti-aging, anti-inflammatory, and antiseptic properties. The herbal cosmetic industry is rapidly growing with a vast scope of multifold expansion in the future. In this article, we have reviewed various herbal plants used in cosmetics along with the regulatory status and evaluation parameters of herbal cosmetics.

Chemical modification of keratin using Schiff bases to prepare cation exchangers and study their adsorption activity

In this research, keratin was chemically modified by Grafting keratin with 4-nitro-aniline, and then a reducing reaction was carried out to reduce the nitro group in order to generate an aromatic amino group on keratin structure to be used in the preparation of Schiff bases. Four exchangers of Schiff bases then were synthesized by reacting five derivatives of benzaldehyde with the crafted keratin. The FTIR, DSC spectra of the prepared exchanges were recorded. The effectiveness of the compounds was tested in the adsorption of some heavy metal ions (copper and lead), as the compounds gave promising results by removing ions from their aqueous solutions in pH (6.5–7), the percentage of removal of copper and lead ions reached about 40%.

Development and structure of the skin in the Australian lungfish (Neoceratodus forsteri) in relation to epidermal adaptation of tetrapods

AbstractAnalysis of skin development in the Australian lungfish, Neoceratodus forsteri, indicates that keratinocytes form 2 to 3 irregular layers in tadpoles of 2–5 cm in length and are fully stratified (7–12 layers) in juveniles of 16.5–26 cm in length. The epidermis produces mucus and mainly contains intermediate filament keratins of acidic nature but also a minute amount of neutral‐basic keratins (pI 7.0–7.3), which is unique among fish. The latter keratins of 60–62 kDa, are generally present in tetrapods but the specific gene structure and amino sequence of acidic, neutral and basic keratins in N. forsteri are presently unknown. No other epidermal proteins are detected although biochemical data suggest the presence of non‐keratin proteins, including a basic type (pI 8.0–8.2) of around 32 kDa of molecular weight. The spinulated bony layer of elasmoid scales contains glycoproteins involved in mineralization, such as osteonectin and osteopontin. Also, alkaline phosphatase, involved in calcium precipitation onto the collagen matrix, has been detected in scales of juveniles up to 26 cm in length. The present review concludes that the knowledge of the data derived from epidermal and dermal protein annotation from the recently sequenced genome of this fish species will contribute to address the study on the evolution of tetrapod skin.

Insights into the keratin efficient degradation mechanism mediated by Bacillus sp. CN2 based on integrating functional degradomics

BackgroundKeratin, the main component of chicken feather, is the third most abundant material after cellulose and chitin. Keratin can be converted into high-value compounds and is considered a potential high-quality protein supplement; However, its recalcitrance makes its breakdown a challenge, and the mechanisms of action of keratinolytic proteases-mediated keratinous substrates degradation are not yet fully elucidated. Bacillus sp. CN2, having many protease-coding genes, is a dominant species in keratin-rich materials environments. To explore the degradation patterns of feather keratin, in this study, we investigated the characteristics of feather degradation by strain CN2 based on the functional-degradomics technology.ResultsBacillus sp. CN2 showed strong feather keratin degradation activities, which could degrade native feathers efficiently resulting in 86.70% weight loss in 24 h, along with the production of 195.05 ± 6.65 U/mL keratinases at 48 h, and the release of 0.40 mg/mL soluble proteins at 60 h. The extracellular protease consortium had wide substrate specificity and exhibited excellent biodegradability toward soluble and insoluble proteins. Importantly, analysis of the extracellular proteome revealed the presence of a highly-efficient keratin degradation system. Firstly, T3 γ-glutamyltransferase provides a reductive force to break the dense disulfide bond structure of keratin. Then S8B serine endopeptidases first hydrolyze keratin to expose more cleavage sites. Finally, keratin is degraded into small peptides under the synergistic action of proteases such as M4, S8C, and S8A. Consistent with this, high-performance liquid chromatography (HPLC) and amino acid analysis showed that the feather keratin hydrolysate contained a large number of soluble peptides and essential amino acids.ConclusionsThe specific expression of γ-glutamyltransferase and co-secretion of endopeptidase and exopeptidase by the Bacillus sp. CN2 play an important role in feather keratin degradation. This insight increases our understanding of the keratinous substrate degradation and may inspire the design of the optimal enzyme cocktails for more efficient exploration of protein resources in industrial applications.

Insights of keratin geometry from agro-industrial wastes: A comparative computational and experimental assessment

Understanding the structural properties of keratin is of great importance to managing their potential application in keratin-inspired biomaterials and its management of wastes. In this work, the molecular structure of chicken feather keratin 1 was characterized by AlphaFold2 and quantum chemistry calculation. The predicted IR spectrum of the N-terminal region of feather keratin 1, consisting of 28 amino acid residues, was used to assign the Raman frequencies of the extracted keratin. The MW of experimental samples were 6 & 1 kDa while the predicted MW (∼10 kDa) of β-keratin. Experimental analysis shows the magnetic field treatment could affect the functional and surface structural properties of keratin. The particle size distribution curve illustrates the dispersion of particle size concentration, while TEM analysis demonstrates the reduction of particle diameter to 23.71 ± 1.1 nm following treatment. High-resolution XPS analysis confirmed the displacement of molecular elements from their orbital.

Bioinspired Processing of Keratin into Upcycled Fibers through pH-Induced Coacervation.

Keratin is an important byproduct of the animal industry, but almost all of it ends up in landfills due to a lack of efficient recycling methods. To make better use of keratin-based natural resources, the current extraction and processing strategies need to be improved or replaced by more sustainable and cost-effective processes. Here, we developed a simple and environmentally benign method to process extracted keratin, using HCl to induce the formation of a coacervate, a separate aqueous phase with a very high protein concentration. Remarkably, this pH-induced coacervation did not result in the denaturation of keratin, and we could even observe an increase in the amount of ordered secondary structures. The low-pH coacervates could be extruded and wet-spun into high-performance keratin fibers, without requiring heating or any organic solvents. The secondary structure of keratin was largely conserved in these regenerated fibers, which exhibited excellent mechanical performance. The process developed in this study represents a simple and environmentally friendly strategy to upcycle waste keratin into high-performance materials.

The bony cap and its distinction from the distal phalanx in humans, cats, and horses.

It has been recognized as early as the Victorian era that the apex of the distal phalanx has a distinct embryological development from the main shaft of the distal phalanx. Recent studies in regenerative medicine have placed an emphasis on the role of the apex of the distal phalanx in bone regrowth. Despite knowledge about the unique aspects of the distal phalanx, all phalanges are often treated as equivalent. Our morphological study reiterates and highlights the special anatomical and embryological properties of the apex of the distal phalanx, and names the apex "the bony cap" to distinguish it. We posit that the distal phalanx shaft is endochondral, while the bony cap is intramembranous and derived from the ectodermal wall. During development, the bony cap may be a separate structure that will fuse to the endochondral distal phalanx in the adult, as it ossifies well before the distal phalanges across taxa. Our study describes and revives the identity of the bony cap, and we identify it in three mammalian species: humans, cats, and horses (Homo sapiens, Felis catus domestica, and Equus caballus). During the embryonic period, we show the bony cap has a thimble-like shape that surrounds the proximal endochondral distal phalanx. The bony cap may thus play an inductive role in the differentiation of the corresponding nail, claw, or hoof (keratin structures) of the digit. When it is not present or develops erroneously, the corresponding keratin structures are affected, and regeneration is inhibited. By terming the bony cap, we hope to inspire more attention to its distinct identity and role in regeneration.

George Ernest Rogers 1927–2021

George Rogers (1927–2021) was elected to Fellowship of the Academy in 1977 for his outstanding contributions to our knowledge of the molecular structure of keratins and the biochemistry of keratinisation. He was a pioneer in the application of electron microscopy to hair and wool ultrastructure and to that of the hair follicle. He discovered citrulline in keratin proteins, and the enzymes, roles, and histochemical localisation of transglutaminase and peptidylarginine deiminase (PAD). He was the first to demonstrate ribosomal-dependent keratin protein synthesis in 1965 followed by detailed studies of the biosynthesis of hair keratin proteins. His research initiated studies on the molecular events in the development of the feather follicle and later led to the cloning and characterisation of the clustered genes of feather and related avian keratins. He also cloned and characterised genes for the three classes of wool keratin proteins and studied the transcription of keratin genes. In 1977, he was awarded a DSc by the University of Adelaide in recognition for his work. In 2013, he was made an Officer in the Order of Australia.

A textile device for the therapy of patients with burn wounds by the use of a drug delivery from a hydrogel to dermis

The paper proposes a textile device for patients with large area burn wounds consisting of an assembly made up of a knitted backing layer, a hydrogel, with an antibiotic content, as a second layer and a membrane with controlled porosity located directly at the interface with the wound. The knit is the material support with a supporting clothing role, but also as a solution tank. The hydrogel has a keratin structure obtained from human hair with advanced swelling capacity and porosity. The study proposes the use of silver sulfadiazine (SSD), an antibiotic used in the topical therapy of burn wounds. The work optimizes the degree of swelling, evaluates the porosity of the hydrogel and designs the support garment for wound therapy. The optimal parameters to obtain the maximal swelling degree are: duration of hydrolytic reaction 180 min, volume of hydrogen peroxide 3.7 mL and duration of oxidation 90–125 min. Based on these optimal parameters one can obtain swelling degrees higher than 1000%. The device proposed is reusable and supports the SSD diffusion to wound.

Physico-Chemical Characterization of Keratin from Wool and Chicken Feathers Extracted Using Refined Chemical Methods.

In this work, the characteristic structure of keratin extracted from two different kinds of industrial waste, namely sheep wool and chicken feathers, using the sulfitolysis method to allow film deposition, has been investigated. The structural and microscopic properties have been studied by means of scanning electron microscopy (SEM), Raman spectroscopy, atomic force microscopy (AFM), and infrared (IR) spectroscopy. Following this, small-angle X-ray scattering (SAXS) analysis for intermediate filaments has been performed. The results indicate that the assembly character of the fiber can be obtained by using the most suitable extraction method, to respond to hydration, thermal, and redox agents. The amorphous part of the fiber and medium range structure is variously affected by the competition between polar bonds (reversible hydrogen bonds) and disulfide bonds (DB), the covalent irreversible ones, and has been investigated by using fine structural methods such as Raman and SAXS, which have depicted in detail the intermediate filaments of keratin from the two different animal origins. The preservation of the secondary structure of the protein obtained does offer a potential for further application of the waste-obtained keratin in polymer films and, possibly, biocomposites.

Therapeutic Textiles Functionalized with Keratin-Based Particles Encapsulating Terbinafine for the Treatment of Onychomycosis.

Onychomycosis is the most common nail fungal infection worldwide. There are several therapy options available for onychomycosis, such as oral antifungals, topicals, and physical treatments. Terbinafine is in the frontline for the treatment of onychomycosis; however, several adverse effects are associated to its oral administration. In this work, innovative keratin-based carriers encapsulating terbinafine were designed to overcome the drawbacks related to the use this drug. Therapeutic textiles functionalized with keratin-based particles (100% keratin; 80% keratin/20% keratin-PEG) encapsulating terbinafine were developed. The controlled release of terbinafine from the functionalized textiles was evaluated against different mimetic biologic solutions (PBS buffer-pH = 7.4, micellar solution and acidic sweat solution-pH = 4.3). The modification of keratin with polyethylene glycol (PEG) moieties favored the release of terbinafine at the end of 48 h for all the solution conditions. When the activity of functionalized textiles was tested against Trichophyton rubrum, a differentiated inhibition was observed. Textiles functionalized with 80% keratin/20% keratin-PEG encapsulating terbinafine showed a 2-fold inhibition halo compared with the textiles containing 100% keratin-encapsulating terbinafine. No activity was observed for the textiles functionalized with keratin-based particles without terbinafine. The systems herein developed revealed therapeutic potential towards nail fungal infections, taking advantage of keratin-based particles affinity to keratin structures and of the keratinase activity of T. rubrum.

A new pachycephalosaurid from the Hell Creek Formation, Garfield County, Montana, U.S.A.

ABSTRACT A partial skull of a pachycephalosaurid from the Upper Cretaceous Hell Creek Formation, Montana, is interpreted as a new taxon, Platytholus clemensi gen. et sp. nov. MOR 2915 does not fit into an ontogenetic continuum of known pachycephalosaurids from the Hell Creek Formation, Montana, and contemporaneous sediments from the Western Interior. Comparisons to known ontogimorphs of Sphaerotholus and Pachycephalosaurus preclude including this specimen into an ontogenetic series of either taxon. We hypothesize that MOR 2915 is a new species based on a relatively low, broad dome at this advanced ontogenetic age that is neither round nor oval in dorsal view, distinct but fused lateral cranial elements fully incorporated into the dome without any dorsal lobe differentiation, and individual tab-like tubercle ornamentation dorsolaterally. Phylogenetic analysis posits that Platytholus clemensi is a Prenocephale-grade taxon deeply nested within Pachycephalosaurinae, but it is not a member of Pachycephalosaurini. Platytholus clemensi is intermediate in size between the other contemporaneous pachycephalosaurids in the Hell Creek Formation and suggests a diverse set of taxa-partitioned ecological niches by body size. We confirm a well organized, major internal vascular network using high resolution computed tomography. Foramina present on the orbital roofs indicate these canals penetrated the entire ceiling of the orbits within the frontal and supraorbital bones. Abundant neurovascular canals passing through the dome to the ectocranial surface indicate a keratinous structure of some kind, possibly with a vertical structural framework, was present on the dome. We review the history of the head-butting hypothesis and associated behavioral implications.

Optimizing the Extraction of Keratin from Cattle Hoof Using Central Composite Design

Cattle hoofs are abundantly available by-product sources of organic material from the slaughterhouse. It can be successfully converted into keratin protein. Keratin extracted using alkali hydrolysis has a better conservancy of keratin structure. The purpose of this study is optimizing the extraction of keratin from cuttle hoof. Designing of the experiment, analysis of the results, and optimization of the process parameters have been conducted by central composite design (CCD). Three factors (temperature (A), time (B), and concentration of NaOH (C)) each at five levels have been used to extract the keratin protein from cattle hoof and two response variables (dissolution % and purity %) have been considered in the study. The results obtained demonstrate that extraction temperature, alkali concentration, and time showed a significant effect on the purity and dissolution of keratin. The regression model shows that all factors have positive and significant relation with dissolution percentage whereas only temperature and concentration of NaOH have significant and negative relation with purity percentage. It is observed that the Biuret and Fourier-transform infrared spectroscopy (FTIR) tests showed better preservation of protein structure in extractive keratin. The FTIR spectra, indicates that amide I and amide II occur at a wave length of 1633 and 1542 cm−1 for raw cattle hoof and at wave length of 1650 and 1542 cm−1 for keratin protein, respectively. Thus, it can be concluded that the cattle hoof by-product could offer an alternative keratin source. Finally, the extraction process had an optimum value of 0.5 M NaOH, 60 minutes reaction time, and 55°C temperature with 85% dissolution and 89.6% purity.

Arginine-fructose-glucose from red ginseng extract reduces stiffness of keratin fiber in corneocyte of skin.

The moisture content of the stratum corneum of the skin changes depending on the external environment. The structure of keratinous fiber protein in corneocyte of the skin changes depending on the amount of moisture. As the moisture decreases, the population of the alpha-helix increases, the beta-sheet deceases, and the stiffness increases accordingly. Here, we investigated the effect of humectants from ginseng on the keratin structure. Corneocyte was prepared from dry porcine skin with disc tape and measured through ATR-FT-IR. The signal from amide I of the keratin protein in corneocyte was detected, and the change in the ratio of alpha-helix and beta-sheet was calculated. The test samples were treated on the exfoliated corneocyte, and the degree of change was checked. Arginine-fructose-glucose (AFG)-enriched extract of red ginseng was effective in changing the keratin structure and was superior to humectants such as glycerin. However, arginine, mono sugar were not effective, and the AFG form in which two sugars were bound to one amino acid could perform its function. The present study suggests that AFG, when applied to cosmetics, is expected to improve skin texture in a different way from existing moisturizers represented by glycerin by reducing the alpha-helix structure of corneocyte keratin.

Synchrotron-based infrared microspectroscopy of polymeric nanoparticles and skin: Unveiling molecular interactions to enhance permeation

The application of nanoparticles as permeation enhancers in skin drug delivery is a growing research field. However, the mechanisms of nanoparticles’ interaction with the skin structure are still unknown. Fucoidan/chitosan nanoparticles have demonstrated several physicochemical and biological advantages, among which is the enhancement of skin permeation. This study aims to elucidate permeation enhancement mechanisms using synchrotron-based Fourier Transform Infrared Microspectroscopy (SR-FTIRM) combined with multivariate analysis and in vitro skin permeation assay. Given the molecular weight influence on chitosan’s properties, the nanoparticles-skin interactions were evaluated with nanoparticles produced using low- and medium-molecular-weight chitosan. Chemical maps and spectral analysis revealed that fucoidan/chitosan nanoparticles induced changes in the lipids and protein regions. Inter-sample spectral differences were identified using principal component analysis. Low molecular weight fucoidan/ chitosan nanoparticles caused changes in the skin lipids’ lateral packing and structure at the stratum corneum layer towards a less ordered state and higher fluidity, and no evidence was found on proteins structure. The opposite was revealed for medium molecular weight fucoidan/chitosan nanoparticles, which induced changes in the secondary structure of keratin and altered lipid structure to an ordered and dense conformation. In vitro permeation assays with Franz diffusion cells correlate with the observed changes in the skin lipid and protein structure with enhanced skin permeation of a hydrophilic molecule incorporated within the fucoidan/chitosan nanoparticles. The findings of this study unveil molecular changes in the skin structure induced by the nanoparticles only possible with the application of the powerful and precise SR-FTIRM technique. This knowledge allows the design of nanoparticles towards an internalization pathway determining their fate within the skin structure.

Stratum Corneum Structure and Function Studied by X-ray Diffraction

X-ray diffraction is one of the powerful tools in the study of a variety of structures in the stratum corneum at the molecular level. Resolving structural modifications during functioning is an important subject for clarifying the mechanism of operating principles in the function. Here, the X-ray diffraction experimental techniques used in the structural study on the stratum corneum are widely and deeply reviewed from a perspective fundamental to the application. Three typical topics obtained from the X-ray diffraction experiments are introduced. The first subject is concerned with the disruption and the recovery of the intercellular lipid structure in the stratum corneum. The second subject is to solve the moisturizing mechanism at the molecular level and the maintenance of normal condition with moisturizer, being studied with special attention to the structure of soft keratin in the corneocytes in the stratum corneum. The third subject is the so-called 500 Da rule in the penetration of drugs or cosmetics into skin, with attention paid to the disordered intercellular lipid structure in the stratum corneum.

New approach for hair keratin characterization: Use of the confocal Raman spectroscopy to assess the effect of thermal stress on human hair fibre.

ObjectiveThe objective of our research was to investigate the heat‐protecting effect of a product ex vivo and in vivo on human hair fibres.MethodsA preparatory study was carried out in order to determine an optimal threshold of thermal stress. For this, the structure of cross‐sections of the hair fibre was observed by optical microscopy. Then, Scanning Electron Microscopy (SEM) and Confocal Raman Spectroscopy (CRS) were applied to analyse ex vivo and in vivo morphological and molecular damage in hair structure after heat stress. Finally, in vivo tests were used to collect consumer perception.ResultsThe preparatory study enabled us to determine an optimal stress threshold of 10 heating cycle for SEM and 5 heating cycle for CRS. Based on spectral hierarchical classification using Ward's clustering algorithm, the ex vivo Raman results show that the spectral signature of the hair treated and heated is very close to the negative control. This shows that the product preserves the keratin structure after thermal stress. These results were also confirmed by an in vivo Raman analysis performed on hair samples from 5 donors. In concordance with Raman results, SEM shows that treated hair presents lesser “bubbles” and “crackling” on the hair surface. Finally, the in vivo studies proved that hair was more protected from heat.ConclusionThe authors concluded that the product shows protective properties with respect to morphological and molecular heat damage. We also demonstrate that the product promotes the α‐helix keratin conformation and preserves the S‐S disulfide bands.

The dexamethasone acetate cubosomes as a potential transdermal delivery system for treating skin inflammation

The aim of this study was to develop the dexamethasone acetate loaded by cubosomes (DA-Cub) and its gel (DA-Cub gel) and improve the drug transdermal penetration and intradermal retention. Dexamethasone acetate cubosomes (DA-Cub) was prepared by hot melt ultrasonic method. The particle size was (110.8 ± 0.87) nm, zeta potential was (−25.9 ± 1.31) mV, and encapsulation efficiency was (97.97 ± 1.06)%. DA-Cub and its gel were characterized by polarizing microscope, transmission electron microscope, differential scanning calorimetry, fourier transform infrared spectroscopy and small-angle x-ray scattering. Both DA-Cub and its gels had sustained-release effect. The accumulation of DA-Cub and DA-Cub gel in rat skin in vitro increased significantly compared with general gels and commercial cream, so the intradermal retention of DA-Cub increased significantly. Compared with the commercial cream, DA-Cub provided higher penetration rate and intradermal retention. HE staining and reflectance fourier transform infrared spectroscopy were used to investigate the effect of transdermal administration of cubosomes on skin surface. DA-Cub and DA-Cub gel could make the cuticle thinner, change the structure of keratin and the intercellular space enlarged, thus promoting the penetration of drugs. DA-Cub has significant therapeutic effect and is expected to become a new low toxic and long-acting preparation.

Tavaborole microemulsion: New strategy for the targeted treatment of onychomycosis

The targeted treatment of onychomycosis becomes a major concern nowadays for onychologist considering the limited permeability of the drug formulation at the nail site due to the number of factors such as complex barrier of keratin structure inside the nail layer, drug-keratin binding properties, as well as lack of availability of promising drug delivery system. In the present study, tavaborole-loaded novel microemulsion and its gel formulation was developed, optimized, and evaluated for the targeted treatment of onychomycosis. The microemulsion formulation was designed and developed using a 32 factorial experimental design approach. The optimized microemulsion formulation consisting of tavaborole (2.5%w/w), glyceryl caprylate/caprate (7.8%w/w), polyethylene glycol-8 caprylate/capric glycerides (21.45%w/w), diethylene glycol monoethyl ether (21.45%w/w) and demineralized water (46.80%w/w) was converted to gel using carbopol® 934P (0.5%w/w). In the ex-vivo bovine hoof membrane model permeation study, the optimized microemulsion formulation exhibited higher drug permeation (116.21 ± 9.75 μg/cm2) and followed the first-order release kinetics mechanism. The in-vitro nail clipping study demonstrated enhanced penetration of tavaborole (0.872 ± 0.019 μg/mg) from optimized microemulsion formulation. It also exhibited improved antifungal activity against dermatophytes species such as Trichophyton rubrum (2.56 ± 0.086 cm), Trichophyton mentagrophytes (3.13 ± 0.097 cm), and Candida albicans (3.63 ± 0.103 cm). The microemulsion formulation did not reveal any toxic and detrimental effects of excipients on nail cells in VERO cell lines cytotoxicity study. Thus, tavaborole loaded microemulsion can be considered as a potential formulation for topical onychomycosis therapy.

Effect of mutations on the hydrophobic interactions of the hierarchical molecular structure and mechanical properties of epithelial keratin 1/10

Human epithelial keratin is an intermediate filament protein that serves as a backbone to maintain the stability of the cell nucleus and mechanical stability of the whole cells. The present study focused on two point mutations, F231L and S233L, of the 1B domain of keratin K 1/10 related to the rare genetic skin disease palmoplantar keratoderma (PPK). We used molecular dynamics simulation to study the effects of the mutations on various hierarchical structures, including heterodimers, tetramers, and octamers of the K1/10 1B domain at the atomic scale. The initial results demonstrated that the wild type and mutant proteins were highly similar at the dimer level but had different microstructures and mechanics at a higher-level assembly. A decrease in the hydrophobic interactions and hydrogen bonds at the terminus resulted in weakened mechanical properties of the tetramer and octamer of the F231L mutant. The asymmetrical structure of the S233L tetramer with an uneven distribution of the hydrogen bonds decreased its mechanical properties. However, the S233L mutation provided extra hydrophobic interactions between these mutated amino acid residues in the octamer, leading to improved mechanical properties. The results of the present study provided a deeper understanding of how the differences in point mutations induced the changes in the configuration and mechanical properties at the molecular scale. The differences in these properties may influence keratin assembly at the microscopic scale and ultimately cause diseases at the macroscopic scale.