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International Journal of Biological... Sep 2022Type I collagen is a ubiquitous structural protein in animal tissues. It is normally present in a hydrated form. However, collagen is very dependent on associated water...
Type I collagen is a ubiquitous structural protein in animal tissues. It is normally present in a hydrated form. However, collagen is very dependent on associated water for its mechanical properties. In skin, where type I collagen is dominant, there is a longstanding concern that the skin and therefore collagen may partially dry out and result in structural degradation. Here we show that dehydration of type I collagen fibrils, using 2-propanol, results in a two-stage dehydration process. Initially, the fibrils do not change length, i.e. the D-period remains constant, but shrinkage occurs within the fibrils by an increase in the gap region and a decrease in the overlap region within a D-band and a shortening of the helical turn distance and fibril diameter. Only with further dehydration does the length of the collagen fibril decrease (a decrease in D-period). This mechanism explains why collagen materials are resistant to gross structural change in the early stages of dehydration and shows why they may then suffer from sudden external shrinkage with further dehydration.
Topics: Animals; Collagen; Collagen Type I; Dehydration; Extracellular Matrix; Skin
PubMed: 35793742
DOI: 10.1016/j.ijbiomac.2022.06.180 -
Biomolecules Feb 2022Hyaluronan (HA) comprises a fundamental component of the extracellular matrix and participates in a variety of biological processes. Half of the total amount of HA in...
Hyaluronan (HA) comprises a fundamental component of the extracellular matrix and participates in a variety of biological processes. Half of the total amount of HA in the human body is present in the skin. HA exhibits a dynamic turnover; its half-life in the skin is less than one day. Nevertheless, the specific participants in the catabolism of HA in the skin have not yet been described in detail, despite the essential role of HA in cutaneous biology. A deeper knowledge of the processes involved will act to support the development of HA-based topical and implantable materials and enhance the understanding of the various related pathological cutaneous conditions. This study aimed to characterize the distribution and activity of hyaluronidases and the other proteins involved in the degradation of HA in healthy human full-thickness skin, the epidermis and the dermis. Hyaluronidase activity was detected for the first time in healthy human skin. The degradation of HA occurred in lysates at an acidic pH. HA gel zymography revealed a single band corresponding to approximately 50 kDa. This study provided the first comprehensive view of the distribution of canonic HA-degrading proteins (HYAL1 and HYAL2) in human skin employing IHF and IHC. Furthermore, contrary to previous assumptions TMEM2, a novel hyaluronidase, as well as CEMIP, a protein involved in HA degradation, were localized in the human epidermis, as well as in the dermis.
Topics: Extracellular Matrix; Humans; Hyaluronic Acid; Hyaluronoglucosaminidase; Proteins; Skin
PubMed: 35204753
DOI: 10.3390/biom12020251 -
Materials (Basel, Switzerland) Feb 2022The collagen superfamily includes more than fifty collagen and/or collagen-like proteins with fibril-forming collagen type I being the most abundant protein within the... (Review)
Review
The collagen superfamily includes more than fifty collagen and/or collagen-like proteins with fibril-forming collagen type I being the most abundant protein within the extracellular matrix. Collagen type I plays a crucial role in a variety of functions, it has been associated with many pathological conditions and it is widely used due to its unique properties. One unique nano-scale characteristic of natural occurring collagen type I fibers is the so-called D-band periodicity, which has been associated with collagen natural structure and properties, while it seems to play a crucial role in the interactions between cells and collagen and in various pathological conditions. An accurate characterization of the surface and structure of collagen fibers, including D-band periodicity, on collagen-based tissues and/or (nano-)biomaterials can be achieved by Atomic Force Microscopy (AFM). AFM is a scanning probe microscope and is among the few techniques that can assess D-band periodicity. This review covers issues related to collagen and collagen D-band periodicity and the use of AFM for studying them. Through a systematic search in databases (PubMed and Scopus) relevant articles were identified. The study of these articles demonstrated that AFM can offer novel information concerning D-band periodicity. This study highlights the importance of studying collagen D-band periodicity and proves that AFM is a powerful tool for investigating a number of different properties related to collagen D-band periodicity.
PubMed: 35208148
DOI: 10.3390/ma15041608 -
Journal of Muscle Research and Cell... Dec 2023The thick filament-associated A-band region of titin is a highly repetitive component of the titin chain with important scaffolding properties that support thick...
The thick filament-associated A-band region of titin is a highly repetitive component of the titin chain with important scaffolding properties that support thick filament assembly. It also has a demonstrated link to human disease. Despite its functional significance, it remains a largely uncharacterized part of the titin protein. Here, we have performed an analysis of sequence and structure conservation of A-band titin, with emphasis on poly-FnIII tandem components. Specifically, we have applied multi-dimensional sequence pairwise similarity analysis to FnIII domains and complemented this with the crystallographic elucidation of the 3D-structure of the FnIII-triplet A84-A86 from the fourth long super-repeat in the C-zone (C4). Structural models serve here as templates to map sequence conservation onto super-repeat C4, which we show is a prototypical representative of titin's C-zone. This templating identifies positionally conserved residue clusters in C super-repeats with the potential of mediating interactions to thick-filament components. Conservation localizes to two super-repeat positions: Ig domains in position 1 and FnIII domains in position 7. The analysis also allows conclusions to be drawn on the conserved architecture of titin's A-band, as well as revisiting and expanding the evolutionary model of titin's A-band.
Topics: Humans; Connectin; Muscle Proteins; Sarcomeres
PubMed: 37258982
DOI: 10.1007/s10974-023-09649-1 -
Methods in Molecular Biology (Clifton,... 2021Electrophoretic mobility shift assays (EMSAs) are among the most frequently used and straightforward experiments for studying protein-nucleic acid interactions. EMSAs...
Electrophoretic mobility shift assays (EMSAs) are among the most frequently used and straightforward experiments for studying protein-nucleic acid interactions. EMSAs rely on the principle that protein-nucleic acid complexes have reduced electrophoretic mobility in a native gel matrix compared to free nucleic acid due to their larger size and reduced negative charge. Therefore, bands for the protein-nucleic acid complexes are shifted in a gel and can be distinguished from free nucleic acids. EMSAs remain a popular technique since they do not require specialist equipment and the complexes formed are easily visualized. Furthermore, the technique can be adapted to enable various aspects of protein-nucleic acid interactions to be investigated, including sequence specificity, estimated binding affinity, and binding stoichiometry.
Topics: Acrylic Resins; Biophysical Phenomena; DNA; Electrophoretic Mobility Shift Assay; Nucleic Acids; Protein Binding; Proteins; RNA
PubMed: 33877605
DOI: 10.1007/978-1-0716-1197-5_14 -
Morphologie : Bulletin de L'Association... Feb 2021The development of the myocardial band shows that it starts and ends at the origin of the great vessels and that the myocardium joins to these rings but does not...
OBJECTIVE
The development of the myocardial band shows that it starts and ends at the origin of the great vessels and that the myocardium joins to these rings but does not inserted into them. We always considered that there should be a fixed end of the muscle band that would allow it a helical rotation to fulfill its fundamental movements of shortening-torsion (systole) and elongation-distortion (suction).
MATERIAL AND METHODS
Seven young-bovine hearts (800-1000g) and seven human hearts (one embryo, 4g; one 10 years, 250g and five adult, 300g/average) were used for a detailed macrocoscopic and microscopic study.
RESULTS
We have found in all the bovine and human hearts studied a nucleus underlying the right trigone, whose osseus, chondroid or tendinous histological structure depends on the specimen analyzed. The microscopic analysis revealed in the hearts a trabecular osteochondral matrix (fulcrum) with segmental lines in bovines and in the ten-year-old human. In the fetus, it was found pre-chondroid areas in a myxoid stroma. In the adult human hearts, the histological analysis revealed a matrix similar to that of a tendon. All the hearts studied presented myocardial attachment to the rigid structure of the fulcrum. Myocardiocytes were not found neither at the left or rigth trigonous nor at the base of the valves.
CONCLUSIONS
The finding of the fulcrum gives support to the spiral myocardial band being the point of fixation that allows the helicoidal torsion.
Topics: Adult; Animals; Cattle; Child; Heart Ventricles; Humans; Myocardium; Rotation; Systole
PubMed: 32646845
DOI: 10.1016/j.morpho.2020.06.010 -
British Dental Journal Nov 2021Sectional matrix techniques offer more predictable solutions to achieving contact areas when placing direct interproximal posterior composites than circumferential...
Sectional matrix techniques offer more predictable solutions to achieving contact areas when placing direct interproximal posterior composites than circumferential matrix techniques, resulting in reduced reported complaints of food packing from patients. Despite this, a large majority of UK dentists and therapists don't currently use them. Sectional matrix systems are technique-sensitive to use, which can be a barrier to implementation for inexperienced users. The matrices can easily distort during their placement and stabilisation and when placing the restorative material. This can result in unwanted, clinically relevant problems in the resulting restorations, some of which may not be discernible once they have occurred. This paper explores the advantages and disadvantages of sectional matrices and the processes and techniques involved in their use, before discussing the potential for distortion at each step. It offers solutions to some of the commonly seen problems which will provide more predictable outcomes for those already using these techniques and encourage non-users to add them to their armamentarium.
Topics: Composite Resins; Dental Cavity Preparation; Dental Materials; Dental Restoration, Permanent; Humans; Matrix Bands
PubMed: 34773017
DOI: 10.1038/s41415-021-3608-5