Macronutrients
Chuong Pham-Huy, Bruno Pham Huy in Food and Lifestyle in Health and Disease, 2022
Fibrous or fibrillar proteins are filiform, long and physically tough. They are mainly of animal origin and are insoluble in all common solvents such as water, acid, alkali solution and organic solvents. Fibrous proteins have structural and protective functions. The fibrous proteins are extremely strong and possess the elastomer characteristics. It is a heterogeneous group and includes the keratins and the proteins of connective tissues found in bones, skin, hair, nails, horns, hoofs, wool, and silk (36, 47). The important examples are: collagens, elastins, keratins, and fibroins. Collagens and their analogs elastins are the proteins of connective tissues, skin, cornea of the eyes, tendons, cartilages, and ligaments. They are also called ‘cellular glue’ as they help give tissues their shape and keep them strong, and are the major proteins of white connective tissues (tendons, cartilage) and of bone. Due to its abundance, strength and its directly proportional relation with skin aging, collagen has gained great interest in the cosmetic industry (51). Elastin has the additional property of being elastic as a rubber band (47). Keratins are rich in cystine, a sulfur amino acid, and are the major components of skin, hair, feathers, hoofs, nails, and horns (47). Fibroins are mainly composed of amino acids; glycine, alanine, and serine and are found in the fibers of silk (47). Fibrin is the protein formed when blood clots.
Atomic Force Microscopy of Biomembranes
Qiu-Xing Jiang in New Techniques for Studying Biomembranes, 2020
Compartmentalizing chemical elements and simple compounds by membranes was probably a very early and important step in the development of life. A biological membrane is an enclosing or separating film that acts as a selectively permeable barrier within living cells.46 In a cell membrane, it contains a variety of biological molecules, notably lipids and proteins. Lipid provides a fluid matrix for proteins to rotate and laterally diffuse, while proteins with their specific functions are responsible for various biological activities, from transmembrane transport to cell signaling, cell adhesion, etc. Proteins can be roughly divided into three main classes: globular proteins, fibrous proteins, and membrane proteins.47 In this chapter, we focus on membrane proteins, which serve as receptors or provide channels for polar or charged molecules to pass through the hydrophobic core of the cell membrane. By using HS-AFM with its latest developments, the dynamics of proteins involved in such processes can be directly visualized and analyzed.
Functions of Glycerine in Cosmetics
Eric Jungermann, Norman O.V. Sonntag in Glycerine, 2018
It was argued that the interaction between glycerine and water limits the water protein interaction thus making a stiffer protein matrix. An interesting aside was that temperatures below 5°C make the stratum corneum stiffer, but above that temperature the elastic modulus is relatively temperature independent. Similar results had been found by Middleton and Allen [43], and later by Van Duzee [61]. Van Duzee stressed that the modulus is a function of the water content, not water activity, suggesting no fundamental interactions in the fibrous protein structure. It should be noted, however, that in this work urea and lithium bromide were used as the humectants. Although not directly related to glycerine, the conclusion of Van Duzee with respect to urea and lithium bromide is interestingly compared with that of Takahshi et al. on a study of hydroxy acids and in vitro skin [62]. The latter used an oscillating rheometer rather than the Instron Tensile tester of Van Duzee. They found that although the uptake of water by sodium lactate is greater at all the relative humidities studied than it was for lactic acid, the actual skin plasticising effects were much greater with lactic acid. Further, with different hydroxy acids, the alpha acids were much more effective in plasticizing skin than the beta acids. They suggest that this is due to a direct interaction between the polar keratin groups of the stratum corneum, and the alpha hydroxy acid moiety. This reduces interchain interaction and results in a more pliable substrate.
Nanocomposite hydrogels for cartilage tissue engineering: a review
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2018
Nahideh Asadi, Effat Alizadeh, Roya Salehi, Bahar Khalandi, Soodabeh Davaran, Abolfazl Akbarzadeh
Chitosan/glycerophosphate (CS/GP) hydrogel, a thermosensitive hydrogel due to its sol–gel-phase transition in body temperature is an important applicable biological substance. Chitosan in complex with other materials such as silk have been studied for biomedical applications. Silk fibroin is a natural fibrous protein and due to its excellent biological compatibility and mechanical strength has been used as a biomaterial for some biomedical applications such as tissue engineering. Fereshteh Mirahmadi and coworkers used degummed chopped silk fibres and electrospun silk fibres to the thermosensitive chitosan/glycerophosphate hydrogels. Their aim was to reinforce the hydrogel constructs for cartilage tissue engineering. They showed that hybrid of hydrogel with two layers of electrospun silk fibres improvesignificantlymechanical properties of them. The expression of GAG and collagen type II indicated the chondrogenic phenotype for chondrocytes with a significant increase in degummed silk fibre-hydrogel composite for GAG content and in two-layer electrospun fibre-hydrogel composite for Col II [23].
Proteomic analysis of pancreatic ductal adenocarcinoma
Published in Expert Review of Proteomics, 2020
Paula Meleady, Rozana Abdul Rahman, Michael Henry, Michael Moriarty, Martin Clynes
PDAC is one of the most stroma-rich cancers, which accounts for 50–80% of the tumor volume. The PDAC stroma supports tumor growth and promotes metastasis; it simultaneously serves as a physical barrier to drug delivery, and is highly resistant to conventional therapies. Activated pancreatic stellate cells (PSCs)/proliferating myofibroblasts are responsible for the production of stromal collagen of the extracellular matrix (ECM) including type 1 collagen and hyaluronic acid, and its function is influenced by pancreatic cancer cells [9]. Other ECM components include fibrous proteins like collagens, laminin and fibronectin and non-collagenous proteins like glycoproteins, proteoglycans and glycosaminoglycans. The ECM also contains components thought to influence stromal-cancer cell interactions, including growth factors, osteopontin, periostin, and serine protein acidic and rich in cysteine (SPARC). The cellular components of the stroma includes immune cells such as lymphocytes, macrophages, mast cells and myeloid derived suppressor cells along with vascular and neural elements (endothelial cells and neurons) [10].
Glaucoma – ‘A Stiff Eye in a Stiff Body’
Published in Current Eye Research, 2023
Sarah Powell, Mustapha Irnaten, Colm O’Brien
At a cellular level, the ECM plays a critical role in aging, stiffness and their downstream pathological consequences. Biologically, stiffness is defined as the ability of a tissue to resist deformation.62 The ECM, an extremely complex yet highly organized structure under constant tight regulatory control, provides a great deal of support-both biochemically and biomechanically- to cellular tissues and also acts as a substrate for cellular processes such as adhesion, differentiation and migration.63 The ECM is fundamentally composed of water, an array of fibrous proteins including collagen, vitronectin and fibronectin, proteoglycans, glycosaminoglycans and polysaccharides.64 Under normal circumstances, dynamic remodeling of ECM following cellular insult or injury functions as a protective cellular mechanism, one that restores tissue function and integrity. The level of ECM stiffness thus plays a central effector role in cellular behaviour.63,65
Related Knowledge Centers
- Globular Protein
- Membrane Protein
- Molecular Biology
- Peptide
- Tendon
- Connective Tissue
- Muscle Cell
- Protein Fold Class
- Protein Structure
- Protein Superfamily