Tritium Labeling of Neuromedin S by Conjugation with [³H]N-Succinimidyl Propionate

Abstract

The human neuropeptide neuromedin S (NMS) consists of 33 amino acids. The introduction of tritium atoms into NMS has not been described so far. This represents a gap for using [ 3 H]NMS in radioreceptor binding assays or in tracking and monitoring their metabolic pathway. Two approaches for the incorporation of tritium into NMS were explored in this study: (1) halogenation at the His-18 residue followed by catalyzed iodine-127/tritium exchange and (2) conjugation of tritiated N -succinimidyl-[2,3- 3 H 3 ]propionate ([ 3 H]NSP) to at least one of the three available primary amines of amino acids Ile-1, Lys-15, and Lys-16 in the peptide sequence. Although iodination of histidine was achieved, subsequent iodine-127/deuterium exchange was unsuccessful. Derivatization at the three possible amino positions in the peptide using nonradioactive NSP resulted in a mixture of unconjugated NSM and 1- to 3-conjugations at different amino acids in the peptide sequence. Each labeling position in the mixture was assigned following detailed LC–MS/MS analysis. After separating the mixture, it was shown in an in vitro fluorometric imaging plate reader (FLIPR) and in a competitive binding assay that the propionyl-modified NMS derivatives were comparable to the unlabeled NMS, regardless of the degree of labeling and the labeling position(s). A molecular simulation with NMS in the binding pocket of the protein neuromedin U receptor 2 (NMUR 2 ) confirmed that the possible labeling positions are located outside the binding region of NMUR 2 . Tritium labeling was achieved at the N-terminal Ile-1 using [ 3 H]NSP in 7% yield with a radiochemical purity of >95% and a molar activity of 90 Ci/mmol. This approach provides access to tritiated NMS and enables new investigations to characterize NMS or corresponding NMS ligands.

A Study on Plasminogen-Ag Nanoparticles Interaction and its Application in Sensor Development

“…The interaction of Ag NPs with BSA has been studied using an electrochemical voltammetric approach, where BSA was found to enhance the dissolution rate of Ag NPs [9]. In addition, electrochemical techniques are known to be among the most facile, cost-effective, and sensitive analytical systems, and thus could be very promising for point-of-care Plg detection [18,24]. We studied the interaction between Ag NPs and Plg on a graphite working electrode in a citrate buffer at pH 4 using SWV, recoding the oxidation peak of Ag NPs at ~0.4 V (Figure 3a).…”

Crystal structure of 2,4-diamino-5-(4-hydroxy-3-methoxyphenyl)-8,8-dimethyl-6-oxo-6,7,8,9-tetrahydro-5H-chromeno[2,3-b]pyridine-3-carbonitrile–dimethylformamide–water (1/1/1)

“…Activated nitriles and �,�-unsaturated nitrile moieties are involved in a wide variety of natural plant products, drugs, colourants and agrochemicals (Fleming & Wang, 2003;Ahmed et al, 2022); they also represent versatile starting materials for the synthesis of a wide variety of therapeutically important heterocycles (Zhang et al, 2019;Metwally et al, 2023). The generally accepted importance of these functions (Wang et al, 2016;Hebishy et al, 2023) is reflected in the investment of much effort to synthesize them (Zhang et al, 2023;Elgemeie et al, 1998a,b).…”

Antibacterial Evolution of ZnO Nanoparticles Synthesized via Wet-Chemical Method

“…Thus, the as-synthesized powder was calcined in Muffle furnace at 600 °C for 2 h and furnace cooled. The resulting product was characterized by XRD, SEM and EDAX [20][21][22].…”

“…Hence, new plans of actions are needed to know and execute the next level of drugs to control microorganisms, which must be effective and affordable therapeutic approaches [17][18][19][20]. In this connection researchers have shown interest in nano ZnO due to its extensive physical, and chemical properties, which offer a wide range of applications, such as energy storage, catalysis, molecular adsorption, ion exchange, water treatment, chemical and biological sensing, photo catalysis, manufacturing of solar cells, sensors, electrical devices and optical coatings and imaging contrast agents [21][22][23][24][25]. In this article we have reported the synthesis of nano ZnO by a wet chemical process and subjected it to characterization to know the morphology and physical properties by Fourier Transform Infrared (FTIR), Xray Diffraction (XRD), Scanning Electron Microscope-Energy Dispersive X-ray (SEM-EDX), and Transmission Electron Microscopy (TEM) analysis.…”