Plasmalogen structure. Influence of ester and ether linkage in phospholipids on the environment and dynamics of the membrane interface: a wavelength-selective fluorescence approach. Benzoate and acetate derivatives of alkylglycerols, alk-1-enylglycerols, alkylacylglycerols, and alk-1-enylacyl-glycerols have proven to be especially useful for analysis by high-performance liquid and gas-liquid chromatography. Phospholipids are amphipathic compounds in a way that the ‘head’ is hydrophilic and the lipophilic ‘tail’ is hydrophobic. Whereas most diacyl-type phospholipids are synthesized in the endoplasmic reticulum, ether phospholipids are synthesized in peroxisomes and changes in levels of ether lipids are associated with peroxisomal disorders. Transfer of electrons resulting from various metabolic pathways in peroxisomes results in hydrogen peroxide generation. Benzoates or other chromophoric derivatives (nitrobenzoates, dinitrobenzoates, and dinitrophenylurethanes) offer an advantage over acetates for analysis because they can be quantitated on the basis of their UV-absorbing properties. However, now, a broad heterogeneity of these has been identified between species, individuals, and organs. Lipids is a broad category of organic compounds that vary greatly in their structure and properties. Although miltefosine has the advantage of being an oral agent, its use predominantly has been evaluated against New World leishmanial strains (i.e., cutaneous and mucosal) and Old World visceral L. donovani, and it may be less effective than other agents. Neural membranes are also enriched in ether phospholipids (i.e., phospholipids with alkyl or alkenyl linkage in the sn-1 position). Fred Snyder, in New Comprehensive Biochemistry, 1996. NCI CPTC Antibody Characterization Program. The complex amino alcohols include choline, … Sterols are the next most abundant lipid, resulting in a cholesterol/phospholipid molar ratio of about 0.12.73 The total cholesterol/total phospholipid ratio, the choline/ethanolamine glycerophospholipid ratio, and the proportion of plasmalogens within these two classes, were much larger in the head than in the tail in the rat.74 It was suggested that the high cholesterol to phospholipid ratio accounts for the lack of thermotropic phase transitions in the plasma membrane of live human sperm detected by Laurdan fluorescence spectroscopy.75 The amount of sterol is much higher in the anterior acrosome than in the postacrosomal region in mammalian sperm (Figure 3.4). 2006 Sep-Oct;23(5):430-41. doi: 10.1080/09687860600803223. They are essential for the normal development of major organs (heart, kidney, brain, lung, liver) and their deficiency causes major malformations of these organs as exemplified by the patients with peroxisomal biogenesis disorders (PBDs) and rhizomelic chondrodysplasia punctate (RCDP).87 In addition, they appear to be important in postnatal life as their secondary deficiency is linked to various age-related diseases. 2014 Jan 21;47(1):12-9. doi: 10.1021/ar400006z. 16). | Synthetic PLs are prepared by attaching both polar and apolar moieties to a glycerol backbone via formation of an ester or ether bond linkage. The protein contains three domains: an FAD-binding domain, a cap domain, and an N-terminal domain. Additionally, the synthesis of sphingomyelins is more complex than that for the glycerophospholipids. Isopropylidenes or trimethyl-silyl ethers of alkylglycerols are also valuable derivatives for gas-liquid chromatographic analysis, especially when combined with mass spectrometry. Stimulation of many G-protein-coupled receptors (GPCRs) leads to activation of phospholipase C (PLC) which hydrolyzes PIP2 to form diacylglycerol (DG), a second messenger for activation of protein kinase C (PKC) and inositol trisphosphate (IP3), a second messenger for mobilization of intracellular Ca2+ stores. Although PI comprises only 4% of total phospholipid, it is metabolically active and is converted to phosphatidylinositol-4-phosphate (PIP) and phosphatidylinositol-4,5-bisphosphates (PIP2) by kinases. Find NCBI SARS-CoV-2 literature, sequence, and clinical content: https://www.ncbi.nlm.nih.gov/sars-cov-2/. Ether glycerophospholipids (also known as plasmalogens) have ether (platelet activating factors, PAF) or vinyl-ether (plasmalogens) bond at the sn-1 position of glycerol linking it with an aliphatic group (R1/FA1) such as C16:0 (palmitic acid), C18:0 (stearic acid), or C18:1 (oleic acid). Five genetically distinct, but clinically indistinguishable, groups exist, three of which are single enzyme defects (types 2, 3, and 4) and the other two of which are peroxisomal biogenesis defects (types 1 and 5) (Waterham et al., 2016). When incorporated in membranes formed by DPPC and DHPC, 2-AS exhibits red edge excitation shift (REES) of 14 and 8 nm, respectively. In contrast, the phospholipid subclasses of ether and ester lipids are not easily separated by adsorption chromatography, although it is sometimes possible to isolate some subclasses of phospholipids and individual molecular species by reverse phase high-performance liquid chromatography. USA.gov. Peroxisomes, identified in 1954 by Rhodin, are single-membrane-bounded organelles. Metabolic diseases, like the Zellweger syndrome, are relying on peroxisomal metabolic impairment and exhibit severe clinical phenotypes. 1997 Apr;72(4):1695-700. doi: 10.1016/S0006-3495(97)78815-5. Acid hydrolysis of the alk-1-enyl linkage produces the corresponding fatty aldehyde. Edward T. Ryan, in Principles and Practice of Pediatric Infectious Diseases (Fifth Edition), 2018. Rebecca L. Fagan, Bruce A. Palfey, in Comprehensive Natural Products II, 2010. Acc Chem Res. This biosynthetic pathway starts in the peroxisome utilizing the first two peroxisomal enzymes, “Dihydroxyacetone phosphate acyltransferase/GNPAT; Alkyl dihydroxyacetone phosphate synthase/AGPS then Acyl/alkyl dihydroxyacetone reductase,” and ends in the ER with the formation of 1-alkenyl-2-acyl-glycerophosphocholine.83–85 The flavoenzyme alkyl dihydroxyacetone phosphate synthase (ADHAPS) carries out the critical step of formation of the vinyl ether bond through an intermediate imino compound.86 While the exact function of plasmalogens is still not fully understood, they are considered to be essential for membrane fluidity and their function(s) may vary in different tissues and organs, and in various metabolic processes and developmental stages. Clipboard, Search History, and several other advanced features are temporarily unavailable. These diradylglycerol derivatives can then be easily resolved into their subclasses and specific molecular species of each subclass by normal adsorption and reverse phase chromatography, respectively. The isoalloxazine of FAD is at this opening with its si face exposed to solvent due to the disordered loop (Figure 9). The structure shows a long tunnel that is covered by a disordered loop at one end. However products of metabolism generated in peroxisomes are transported to different organelles by vesicular transport and diffusion as well. It is proposed that an active site base deprotonates the C1′-position of acyl-DHAP forming an enolate intermediate (Scheme 27). Steady-state analysis490,491 shows that ADPS uses a ping-pong mechanism with a turnover number of ∼1 s−1. Found in major organs (brain, heart, kidney), brain myelin has a high content of phosphatidylethanolamine while myocardium contains phosphatidylcholine. J Membr Biol. Different phospholipids have different structures, properties, and importance in the human body. In addition, the fluorescence polarization values of 2-AS are found to be higher in DHPC membranes than in DPPC membranes. PEpl is especially enriched in myelin, comprising more than 60% of total ethanolamine phospholipids. 11.5), of which the vinyl-ethers constitute a class of ether phospholipids called plasmalogens.
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