Cellular and Molecular Basis of Human Biology
Lawrence S. Chan, William C. Tang in Engineering-Medicine, 2019
Structural proteins are responsible for creating a functional frameworks of human structure and function, like muscles, tendon, bone, cartilage, skin, hair, nail, etc. Although the major skeletal muscle proteins include common contractile proteins of slow type 1 and fast types 2A and 2X myosins, actins, tropomyosins, troponin complexes, and metabolic proteins, there is a high variability in terms of relative composition since muscle protein types vary with age, activity type and level, and gender (Gelfi et al. 2011). In bone, about 90% of protein is in the form of type I collagen (Lammi et al. 2006). In cartilage, type II collagen and aggrecans (large aggregating chondroitin sulfate proteoglycan) predominate (Lammi et al. 2006). In tendon, the major proteins are type I (most abundant), II, and III collagens (Buckley et al. 2013). For the skin, collagen is one of the major protein components. Hair and nail proteins are primarily keratins.
Dietary treatment of overweight and obesity
G. Michael Steelman, Eric C. Westman in Obesity, 2016
Protein is the major structural component of the human body. Dietary protein is the source of amino acids to provide the building blocks to make proteins, and when used for energy, burned in a bomb calorimeter, contains 4 kcal/g. Protein is required in the human diet because there are nine essential amino acids that the body cannot manufacture by itself (“essential” means that the body is unable to synthesize the nutrient). Although maintenance dietary protein needs are estimated to be from 0.7 to 1.0 mg/kg/day, 1.2 to 1.5 g/kg lean body weight of dietary protein is needed for preservation of lean body mass and physical performance during weight loss (12). Picking the value of 1.5 g/kg/day, for adults with reference weights ranging from 60 to 80 kg, this translates into total daily protein intakes between 90 and 120 g/day. When expressed in the context of total daily energy expenditures of 2000 to 3000 kcal/day, about 15% of an individual’s daily energy expenditure (or intake if the diet is eucaloric) needs to be provided as protein. During weight loss, especially if strenuous exercise is a component of the process, more dietary protein may be advantageous.
Effects of Loading and Nutrition on Fascia
David Lesondak, Angeli Maun Akey in Fascia, Function, and Medical Applications, 2020
Connective tissues including bone, cartilage, tendon, ligaments, and fascia, are critical components of a functioning musculoskeletal system. These tissues serve to absorb, transmit, and dissipate the forces applied to the body during movement. Each one is specialized for one or more mechanical functions based on the location in the body and the resulting amount and type of force applied to the cells within the tissue. Tendons, ligaments, and fascia function primarily to transfer force within the musculoskeletal system. Fascia has the added function of facilitating movements by lubricating the interface between tissues. To facilitate the transfer of force, these connective tissues are composed of an extracellular matrix (ECM) composed of structural proteins, which give them a high tensile strength,1 and ground substance. The primary structural proteins are collagen, laminin, and elastin, with collagen contributing ~80% of the total protein. There are 28 different collagen proteins.2 Within the musculoskeletal connective tissues, type I collagen makes up more than 90% of the collagen fraction, with type III collagen comprising much of the remaining fraction. Therefore, types I and III collagen are the major fibrillar collagens that provide tensile strength to the musculoskeletal connective tissues.1
Serum and plasma amino acids as markers of prediabetes, insulin resistance, and incident diabetes
Published in Critical Reviews in Clinical Laboratory Sciences, 2018
C. Gar, M. Rottenkolber, C. Prehn, J. Adamski, J. Seissler, A. Lechner
Protein provides the most important structural and functional components of the human body. Muscle protein in particular also serves as an energy store. Protein-derived amino acids are constantly turned over and transported between organs and the blood stream. In anabolic phases, dietary amino acids are added to the body’s protein pool. These phases alternate with catabolic states, which occur with energy deprivation or when dietary protein is available in excess of structural requirements. Then energy is provided by the breakdown of endogenous protein and amino acids can be used for gluconeogenesis [16]. Over-activation of gluconeogenesis occurs in most cases of prediabetes and T2D [17,18]. Glucagon stimulates this process in the liver and, to a lower extent, in the kidneys [16]. After deamination, amino acids form keto acids like acetyl-CoA (derived from leucine, isoleucine, lysine, and tryptophan), alpha-ketoglutarate (derived from glutamate, glutamine, arginine, proline, and histidine), succinyl-CoA (derived from valine), and fumarate (derived from aspartate, asparagine, tyrosine, and phenylalanine), which are further metabolized to oxaloacetate in the Krebs-cycle (Figure 1) [16,19]. Deamination of asparagine and aspartate directly forms oxaloacetate and alanine; the deamination of cysteine, glycine, serine, and tryptophan form pyruvate. Oxaloacetate and pyruvate feed gluconeogenesis [16,19]. Among the amino acids, alanine and glutamine are the most important gluconeogenic precursors in liver (major site of gluconeogenesis) [20–22].
Novel strategies for the development of hand, foot, and mouth disease vaccines and antiviral therapies
Published in Expert Opinion on Drug Discovery, 2022
Structural biology is the study of molecular structure of biological macromolecules (e.g. RNA, DNA, amino acids, protein, lipids, membranes, viral particles, and antibodies), and understanding how they are constructed, how their structure changes, how their structures affect their functions, and how they affect their interactions are discussed [121]. Macromolecules perform most of the functions in cells, and the formation of specific three-dimensional (3D) structures is required to perform their functions. In the past years, many of studies of X-ray diffraction, Cryo-EM (cryogenic electron microscopy), and computer simulations have established the high-precision physical molecular models for the study of viral structure and function. It has become feasible using highly accurate physical molecular models in in silico study of biological structures. Many 3D models of macromolecules and simulation tools can be found in the Protein Data Bank of NCBI, which all contribute for bioinformatics.
Anti-photoaging effects of flexible nanoliposomes encapsulated Moringa oleifera Lam. isothiocyanate in UVB-induced cell damage in HaCaT cells
Published in Drug Delivery, 2022
Yijin Wang, Qianqian Ouyang, Xuefei Chang, Min Yang, Junpeng He, Yang Tian, Jun Sheng
Proteolytic enzymes such as MMPs and elastases are produced by epidermal keratinocytes and fibroblasts in the mediation of ECM remodeling (Philips et al., 2011). The MMPs initiate the photoaging of the skin by acting as collagenases (Mu et al., 2021). Collagen and elastin are the major structural proteins in the ECM. The basal levels of the enzymes increase under various conditions such as aging; however, they increase considerably more under environmental pollutants and UV radiation. The UV radiation induces high expressions of MMP-1, MMP-3, and MMP-9. MMP-1 is the most important enzyme for degrading the components of the ECM and breaking the normal structure of collagen fibers and elastic fibers; MMP-3 is a stromelysin; and MMP-9 degrades denatured collagens (Quan et al., 2009). The changes of MMP1, MMP3, and MMP9 were not obvious when drugs were stored for one day (Fig. S3), five days (Fig. S4), and 10 days (Figure 10). MMP-1 is the most important enzyme for degrading the components of the ECM and breaking the normal structure of collagen and elastic fibers; MMP-3 is a stromelysin; and MMP-9 degrades denatured collagens. The expressions of MMP-1, MMP-3, and MMP-9 are significantly higher than those of the normal group (p < .05). Further, when treated with HACE/MITC NPs, the expressions were significantly decreased compared with those for the UVB group (p < .05).