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Bioenergetics
Published in Michael H. Stone, Timothy J. Suchomel, W. Guy Hornsby, John P. Wagle, Aaron J. Cunanan, Strength and Conditioning in Sports, 2023
Michael H. Stone, Timothy J. Suchomel, W. Guy Hornsby, John P. Wagle, Aaron J. Cunanan
Beta-oxidation is a process of extracting energy from FFA. Beta-oxidation is primarily a function of the mitochondrial trifunctional protein. The MTFP is an enzyme complex associated with the inner mitochondrial membrane, although especially long-chain FA are oxidized in oxidative organelles, the peroxisomes. The peroxisomes use a similar oxidative enzyme group as found in the inner mitochondrial membrane. Free fatty acids undergoing β-oxidation result in the accumulation of acetyl-CoA, and H+. The acetyl-CoA can enter the Krebs cycle and the protons, which are carried to the ETS by nicotinic adenine dinucleotide (NAD) and flavin adenine dinucleotide (FAD), can enter the electron transport system (ETS) (see Figure 2.5). Type I muscle fibers generally contain high concentrations of oxidative enzymes compared to type II, thus the process of FFA oxidation is quite important for these fibers (35, 79). Fat use during exercise becomes increasingly important with duration (108).
Neonatal adrenoleukodystrophy/disorders of peroxisomal biogenesis
Published in William L. Nyhan, Georg F. Hoffmann, Aida I. Al-Aqeel, Bruce A. Barshop, Atlas of Inherited Metabolic Diseases, 2020
William L. Nyhan, Georg F. Hoffmann, Aida I. Al-Aqeel, Bruce A. Barshop
Peroxisomal biogenesis requires the synthesis of proteins on cytosolic polyribosomes and post-translational import to pre-existing peroxisomes, which enlarge until they divide and form new peroxisomes. Matrix proteins include catalase, the bifunctional hydratase-dehydrogenase enzyme, the thiolase, and acylCoA oxidase [6]. Peroxisomal matrix proteins carrying either a carboxy terminal peroxisomal targeting sequence (PTS1) or a cleavable amino terminal sequence (PTS2) are translocated across the peroxisomal membrane [58–60]. A defect in a peroxin, caused by mutation in a PEX gene leads to failure of protein import via either the PTS1 or PTS2 import pathway and, as a consequence, to functional deficiency of the peroxisomes.
Mulibrey Nanism
Published in Dongyou Liu, Handbook of Tumor Syndromes, 2020
Being single-membrane–bound subcellular organelles, peroxisomes participate in numerous metabolic processes (e.g., β-oxidation of long- and very-long-chain fatty acids; biosynthesis of plasmalogens, cholesterol, and bile acid; and the degradation of amino acids and purine). Mutations in genes encoding peroxisomal proteins may result in single peroxisomal enzyme defect as well as defective biogenesis of the peroxisome (i.e., peroxisome biogenesis disorders). Not surprisingly, many clinical features of mulibrey nanism (e.g., prenatal-onset growth failure, facial dysmorphism, hepatomegaly, pigmentary changes in retina, and muscular weakness) are also found in other peroxisome biogenesis disorders, including Zellweger syndrome, neonatal adrenoleukodystrophy, infantile Refsum disease, and rhizomelic chondrodysplasia punctata type 1. However, compared to other peroxisomal disorders, mulibrey nanism tends to have a mild course and does not induce neurological symptoms. The life span of patients with mulibrey nanism is largely influenced by accompanying cardiopathy.
Dual transcriptome of Streptococcus mutans and Candida albicans interplay in biofilms
Published in Journal of Oral Microbiology, 2023
Yan Zeng, Elena Rustchenko, Xinyan Huang, Tong Tong Wu, Megan L. Falsetta, Jin Xiao
Most studies have focused on the effect of C. albicans on S. mutans virulence and biofilm formation. Therefore, we also focused on the molecular changes in C. albicans during duo-species interactions. We found that the transcriptomic profile of C. albicans was significantly altered when co-cultured with S. mutans in duo-species biofilms. Compared to C. albicans single species-biofilms, we identified 92 C. albicans DEGs (with over 3-fold Log2 fold change) in the duo-species biofilms. The majority of C. albicans DEGs that related to metabolism pathways were up-regulated, such as ARG3, PXP2, and CAT1. ARG3 is related to arginine biosynthesis. The critical roles of the C. albicans arginine biosynthesis pathway in its cross-kingdom interactions with Actinomyces viscosus in root caries were identified recently, and the study results indicated that targeting this pathway was a practical way to treat root caries caused by multiple species [34]. PXP2 relates to fatty acid degradation and the peroxisome pathway. The peroxisome plays an essential role in eukaryotic cellular metabolism, including beta-oxidation of fatty acids and detoxification of hydrogen peroxide [35]. CAT1 is a catalase-specific inhibitor that can suppress the hyphal growth of wild-type cells, and it is also involved in C. albicans peroxisome, MAPK signaling, and longevity regulating pathways.
Putative adjunct therapies to target mitochondrial dysfunction and oxidative stress in phenylketonuria, lysosomal storage disorders and peroxisomal disorders
Published in Expert Opinion on Orphan Drugs, 2020
Nadia Turton, Tricia Rutherford, Dick Thijssen, Iain P Hargreaves
Peroxisomes are membrane-bound organelles which contain around 50 different enzymes to fulfil their critical roles in a range of metabolic processes including catabolism of polyamines, prostaglandins, purines and eicosanoids, ether phospholipid biosynthesis, fatty acid oxidation, peroxide and ROS metabolism, glyoxylate clearing, and possibly the biosynthesis of isoprenoids [64]. Peroxisomal disorders are heterogeneous metabolic diseases that result from either mutations in genes that encode peroxisomal enzymes (Refsum disease and adrenoleucodystrophy: ALD) [65,66] or occur as the result of defects in peroxisome biogenesis (Zellweger syndrome spectrum disorders and Rhizomelic chondrodysplasia punctate: RCDP) [67]. Peroxisome biogenesis disorders encompass two phenotypic groups: 1. Zellweger syndrome, neonatal ALD, and infantile Refsum disease, which all belong to the Zellweger syndrome spectrum of diseases, and 2. RCDP1 [67].
A conjunctive lipidomic approach reveals plasma ethanolamine plasmalogens and fatty acids as early diagnostic biomarkers for colorectal cancer patients
Published in Expert Review of Proteomics, 2020
Tong Liu, Zhirong Tan, Jing Yu, Feng Peng, Jiwei Guo, Wenhui Meng, Yao Chen, Tai Rao, Zhaoqian Liu, Jingbo Peng
PlsEtns are peroxisome-derived glycerophospholipids, in which the ether bond is attached at the sn-1 position of the glycerol backbone [32]. Seven steps are essential for plasmalogen synthesis; the first two steps take place in the peroxisomes [33]. The resident enzymes of a peroxisome are imported into the organelle by a transport system that consists of many proteins. The peroxisomal enzymes, alkylglycerone-phosphate synthase (AGPS), fatty alcohol reductase (FAR), and glyceronephosphate O-acyltransferase (GNPAT), as rate-limiting steps for plasmalogen biosynthesis, catalyze the key steps in the synthesis of 1-alkyl-dihydroxyacetone phosphate. In a colorectal cancer study, mRNA levels of the key peroxisomal enzymes (FAR2, AGPS, and GNPAT) were downregulated in adenomatous polyps and were increased in colon carcinoma compared with those in healthy patients [34]. In addition, elevated mRNA expression levels of FAR1, AGPS, and GNPAT were reported in lymphoma cells [35].