China
Africa
Explore chapters and articles related to this topic
Cell Biology for Bioprocessing
Published in Wei-Shou Hu, Cell Culture Bioprocess Engineering, 2020
Lysosomes are small organelles where the degradation of many cellular materials takes place. Its lumen is a low pH environment (pH ~4.5) and it contains many enzymes that hydrolyze proteins, nucleic acids, and lipids (Panel 2.13). It has proton pumps in the membrane to maintain a low interior pH. It is the site of degradation of both ingested materials and cellular materials that are no longer needed by the cell. Most cellular materials have a finite life span, regardless of whether they are catalyzing chemical reactions or playing structural or mechanical roles. Over time, any cellular material can be oxidized or chemically modified in other ways in some part of its structure. The accumulation of such “damages” may render a protein non-functional. Thus, most proteins and other cellular materials, such as RNAs and lipids, are turned over after a finite period of time. Many of such processes occur in lysosomes. For some proteins, this occurs in proteasomes. Proteasomes are complexes of proteolytic enzymes that are capable of degrading proteins. Proteins that need to be turned over are tagged by ubiquitin and sent to the proteasome for degradation. Lysosomes are not trash cans, but rather more like recycling centers. They play an important role in lipid homeostasis. Lipids taken up from the extracellular environment and other organelles are processed and then redistributed to maintain the proper lipid composition in the membranes of different organelles.
General Introductory Topics
Published in Vadim Backman, Adam Wax, Hao F. Zhang, A Laboratory Manual in Biophotonics, 2018
Vadim Backman, Adam Wax, Hao F. Zhang
Lysosomes are the main centers of catabolism. Old organelles are delivered to the lysosomes for degradation. Lysosomes are filled with acid hydrolases (about 40 different enzymes) such as proteases (for protein degradation), nucleases, lipases (digestion of lipids), etc. Proteasomes are large protein complexes. Each proteasome is a cylinder-like structure composed of several different proteases. These are responsible for degradation of misfolded proteins. The latter are tagged by protein ubiquitin and fed to a proteasome. The role of peroxisomes is β-oxidation of fatty acids. Much like mitochondria, peroxisomes are self-replicating. The main difference is that peroxisomes lack their own DNA and ribosomes and depend entirely on the availability of proteins free-floating in the cytosol.
Outdoor Emissions
Published in William J. Rea, Kalpana D. Patel, Reversibility of Chronic Disease and Hypersensitivity, Volume 4, 2017
William J. Rea, Kalpana D. Patel
Degradation according to Mostafalou et al.876 of misfolded, damaged, or unneeded proteins is a fundamental biological process which has a crucial role in maintenance and regulation of cellular function. There are two major cellular mechanisms for protein degradation; ubiquitin-proteasome system (UPS) that mainly targets short-lived proteins by proteases, and autophagy that at most clears long-lived and poorly soluble proteins through the lysosomal machinery.885 UPS is composed of ubiquitin for tagging and proteasomes for proteolysis of proteins, which are to be degraded. Deregulation of this system has been implicated in the pathogenesis of several chronic diseases, mostly neurodegeneration and cancers evidenced by decreased and increased proteasome activity, respectively.886
Exenatide promotes the autophagic function in the diabetic hippocampus: a review
Published in Egyptian Journal of Basic and Applied Sciences, 2022
Eman Mohammed Elsaeed, Ahmed Gamal Abdelghafour Hamad, Omnia S. Erfan, Mona A. El-Shahat, Fathy Abd Elghany Ebrahim
The degradation of cellular components can be achieved by two major systems: the ubiquitin-proteasome system and autophagy. The ubiquitin-proteasome system is concerned with the degradation of the short-lived proteins, as they are tagged by ubiquitin, and recognized and degraded by the proteasome. Autophagy is the process by which eukaryotic cells get rid of intracellular organelles and protein aggregates that cannot be degraded by the proteasome. It degrades long-lived proteins, lipids, and cytoplasmic organelles via a lysosome-driven process [15, 16]. It occurs at a basal level in all cells, and it helps maintain cellular homeostasis. Also, it is proven to have a role in development and disease [17].
Zinc(II)-Schiff base complex functionalized on gold nanospheres: synthesis, characterization, anticancer study and interaction with proteins
Published in Journal of Coordination Chemistry, 2022
Yin Zhuang Ng, Kong Wai Tan, Lip Yong Chung, Fatimah Salim, May Lee Low, Ing Hong Ooi, Foo Win Yip, Chew Hee Ng
Related to their potential toxicity and application in biological system in the fields of drug delivery, biosensing, biological imaging, gene therapy, and photothermal therapy is the interaction of nanoparticles and surface-functionalized nanoparticles, that is, nanoparticle conjugates, with various biomolecules [23–25]. As the NP particles enter the biological system, they interact with many proteins of different size and quantity; it is important to understand the nature of such interaction and fate of the NP-protein complexes formed which are the active species that determine the response in the biological system [26–28]. For AuNPs, factors, such as size and shape, have been identified to affect their permeability and cellular uptake [23]. The conformations of proteins are important to their biological activities and their interaction with nanoparticles can alter their conformation or structure to varying degree [29]. In turn, proteins may affect the properties of AuNPs [30]. Among the proteins, serum albumins are of particular importance as they are the main soluble protein constituents of the blood circulatory system, and bovine serum albumin (BSA) has been one of the most extensively studied of this group of proteins because of its structural homology with human serum albumin (HSA) [31, 32]. Another ubiquitous biomolecule of interest is proteasome, a multiprotein complex responsible for degradation of misfolded, damaged, unnecessary and short-lived regulatory proteins involved in various biological processes [33]. Nanomaterials, with potential of higher binding affinity because of their higher surface free energy, have been established to bind to proteasome and regulate its proteolytic activity [34]. Herein, we report the preparation and characterization of the nanogold conjugated with N,N’-bis(salicylidene)-1,2-phenylenediamine (salenphen) via thioctic acid linker, and its anticancer property, cell membrane permeability and interaction with BSA and proteasome.