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Innovations in Noninvasive Instrumentation and Measurements
Published in Robert B. Northrop, Non-Invasive Instrumentation and Measurement in Medical Diagnosis, 2017
It is known that certain cancer cells produce an excess of a class of molecule known as pteridines. Figure 17.6 illustrates the structural formulas of three common pteridines (pteridine, pterin, and biopterin). Pteridines are a class of bicyclic heterocyclic molecules, the more important of which are folic acid, biopterin, and their derivatives. Biopterin in its tetrahydro form participates in the enzymatic conversion of the AAs phenylalanine, tyrosine, and tryptophan by various hydroxylation reactions to different members of the catecholamine family, important neurotransmitters. Tetrahydrobiopterin (THBP) is also an essential factor in the three forms of nitric oxide (NO) synthase. NO is an important cell-signaling substance.
Thin-Layer Chromatography in the Study of Entomology
Published in Bernard Fried, Joseph Sherma, Practical Thin-Layer Chromatography, 2017
The detection of pteridine pigments is made by UV light at 366 nm. Ommochromes can be detected by their natural color or by UV absorption at 254 or 375 nm.126 Carotenoids can also be detected by their natural color (typically yellow to red). The spots of the retinal chromophores can be detected by exposure of plates to iodine vapors or by spraying the plates with SbCl3.124
Modelling of growth kinetics of isolated Pseudomonas sp. and optimisation of parameters for enhancement of xanthine oxidoreductase production by statistical design of experiments
Published in Journal of Environmental Science and Health, Part A, 2019
Xanthine oxidoreductase (XOR) is an iron-sulphur containing metalloflavoprotein that catalyses the hydroxylation of purine, pyrimidine, pterin, pteridine and aldehydes.[1] NAD+ dependent Xanthine dehydrogenase (XDH, D-form; EC1.1.1.204; xanthine-NAD oxidoreductase) is a precursor of xanthine oxidase (XOD, o-form; EC 1.1.3.22; xanthine: oxygen oxidoreductase) that may be formed either by conversion of proteolytic cleavage of –SH (thiol)Cys535 located in the long peptide chain between FAD centre and molybdoprterin domains or by oxidation of sulfhydryl residues of protein molecule.[2] Corte and Stirpe[3] reported XDH as a native form of XOD and both are responsible to control the rate limiting step of nucleic acid oxidation. XOR is gaining interest due to its use in food processing industries and medical diagnostics to monitor xanthine (XN) and hypoxanthine (HX) using enzyme-based analytical methods such as biosensor, spectrophotometric and immunologic analyses. Quantification of XN and HX is useful to detect freshness of fish/meat derivatives in food processing industries.[4] XOR has potential to treat many diseases, e.g., hyperuricemia, gout, xanthinuria and renal failure. Hence, large scale production of XOR is important for low cost monitoring of XN in biological samples. Commercial enzyme production is achieved by overproducing biomass of selective strains that synthesise desired enzyme at optimal fermentation parameters. Separation and purification of the enzyme from an organism involve few crucial steps such as screening of microorganism, enrichment in media, optimisation of fermentation conditions, disruption of the cells, removal of cell debris and nucleic acids, precipitation of proteins, ultrafiltration and chromatographic purification of the desired enzyme.
Biomolecules of Similar Charge Polarity Form Hybrid Gel
Published in Soft Materials, 2022
Pankaj Pandey, Vinod Kumar Aswal, Joachim Kohlbrecher, Himadri B. Bohidar
FA is the synthetic form of folate, an important member of vitamin B family. Structurally, FA is in an extended conformation with the pteridine ring (fused pyrimidine and pyrazine rings) in the keto form where the C(4) oxygen and N(10) atoms are located on the same side of the molecule.[7] Very often the FA pteridine and phenyl rings interact in a stacking manner which lead to the of association these groups to form a complex of folate, dihydrofolate reductase, and reduced nicotinamide adenine dinucleotide phosphate. FA with the molecular formula of C19H19, has a nominal molecular weight of ≈ 441 Da. The crystal and molecular structure of FA has been determined by x-ray diffraction.[8] Because of the intrinsic hydrophobicity of FA, its water dispersibility is marginal. By the manipulation of hydrophobicity, native FA, which behaves as a super-gelator in DMSO–water binary solvent, can be made to generate a supramolecular gel. FA supramolecular gels made in water-organic solvent binary mixtures have been reported.[9] It has been realized that native FA can serve as an efficient molecular building block, and as a super-gelator to produce multi-responsive soft materials.[10,11] Folate plays an important role for a range of regulatory functions in the human body. It is required for the synthesis and repair of DNA and other genetic material, production and maintenance of new cells including RBCs, and it is also necessary for cell division. Folate deficiency can lead to severe anemia, and during pregnancy, to neural tube irregularities, such as spina bifida and anencephaly. FA derived hydrogel enhances the survival and promotes therapeutic efficacy of iPS Cells for acute myocardial infarction.[12] The hierarchical self-assembly of FA supramolecular hydrogels offer robust mechanical elastic modulus comparable to synthetic double-network polymer gels.[13]