Phototherapy is commonly used for the treatment of neonatal jaundice. Riboflavin is a photosensitizer that generates singlet oxygen, which promotes bilirubin photodecomposition. Metalloporphyrins are also effective photosensitizers. The effect of a combined dosing regimen of riboflavin and metalloporphyrins was studied, with the aim of increasing the efficiency of the phototherapeutic treatment of hyperbilirubinemia. It was envisaged that riboflavin and the metalloporphyrins, by promoting the photodecomposition of bilirubin, would thereby lead to a reduction of the toxic side effects associated with phototherapy. The results shows that a phototherapeutic treatment, in which riboflavin and metalloporphyrins were co-administered, was effective in reducing Heme Oxygenase activity. However, a comprehensive study of the possible side effects of metalloporphyrin treatment in the wavelength under consideration is essential prior to utilizing these compounds for any clinical applications.
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http://dx.doi.org/10.1081/bio-200066613 | DOI Listing |
J Biol Inorg Chem
September 2024
College of Pharmacy, University of New Mexico, Albuquerque, NM, 87131, USA.
Nitric oxide synthases (NOSs), a family of flavo-hemoproteins with relatively rigid domains linked by flexible regions, require optimal FMN domain docking to the heme domain for efficient interdomain electron transfer (IET). To probe the FMN-heme interdomain docking, the magnetic dipole interactions between the FMN semiquinone radical (FMNH) and the low-spin ferric heme centers in oxygenase/FMN (oxyFMN) constructs of neuronal and inducible NOS (nNOS and iNOS, respectively) were measured using the relaxation-induced dipolar modulation enhancement (RIDME) technique. The FMNH RIDME data were analyzed using the mesoscale Monte Carlo calculations of conformational distributions of NOS, which were improved to account for the native degrees of freedom of the amino acid residues constituting the flexible interdomain tethers.
View Article and Find Full Text PDFBiochemistry
June 2024
Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico, Albuquerque, New Mexico 87131, United States.
Nitric oxide synthase (NOS) in mammals is a family of multidomain proteins in which interdomain electron transfer (IET) is controlled by domain-domain interactions. Calmodulin (CaM) binds to the canonical CaM-binding site in the linker region between the FMN and heme domains of NOS and allows tethered FMN domain motions, enabling an intersubunit FMN-heme IET in the output state for NO production. Our previous cross-linking mass spectrometric (XL MS) results demonstrated site-specific protein dynamics in the CaM-responsive regions of rat neuronal NOS (nNOS) reductase construct, a monomeric protein [Jiang et al.
View Article and Find Full Text PDFNature
March 2024
State Key Laboratory of Membrane Biology, College of Future Technology, Institute of Molecular Medicine, Peking University, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Beijing, China.
Phagocyte NADPH oxidase, a protein complex with a core made up of NOX2 and p22 subunits, is responsible for transferring electrons from intracellular NADPH to extracellular oxygen. This process generates superoxide anions that are vital for killing pathogens. The activation of phagocyte NADPH oxidase requires membrane translocation and the binding of several cytosolic factors.
View Article and Find Full Text PDFJ Biol Chem
July 2023
Department of Chemistry, University of British Columbia, Kelowna, Canada. Electronic address:
Fusobacterium nucleatum is an opportunistic oral pathogen that is associated with various cancers. To fulfill its essential need for iron, this anaerobe will express heme uptake machinery encoded at a single genetic locus. The heme uptake operon includes HmuW, a class C radical SAM-dependent methyltransferase that degrades heme anaerobically to release Fe and a linear tetrapyrrole called anaerobilin.
View Article and Find Full Text PDFMicrob Cell Fact
September 2022
Institute for Bioengineering, School of Engineering, The University of Edinburgh, Edinburgh, EH9 3BF, UK.
Background: CYP725A4 catalyses the conversion of the first Taxol® precursor, taxadiene, to taxadiene-5α-ol (T5α-ol) and a range of other mono- and di-hydroxylated side products (oxygenated taxanes). Initially known to undergo a radical rebound mechanism, the recent studies have revealed that an intermediate epoxide mediates the formation of the main characterised products of the enzyme, being T5α-ol, 5(12)-oxa-3(11)-cyclotaxane (OCT) and its isomer, 5(11)-oxa-3(11)-cyclotaxane (iso-OCT) as well as taxadienediols. Besides the high side product: main product ratio and the low main product titre, CYP725A4 is also known for its slow enzymatic activity, massively hindering further progress in heterologous production of Taxol® precursors.
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