RESUMEN
Dynamic ligand layers on nanoparticle surfaces could prove to be critically important to enhance the functionality of individual materials. Such capabilities could complement the properties of the inorganic component to provide multifunctionality or the ability to be remotely actuated. Peptide-based ligands have demonstrated the ability to be remotely responsive to structural changes when adsorbed to nanoparticle surfaces via incorporation of photoswitches into their molecular structure. In this contribution, direct spectroscopic evidence of the remote actuation of a photoswitchable peptide adsorbed onto Au nanoparticles is demonstrated using X-ray absorption fine structure spectroscopic methods. From this analysis, Au-X (X = C or N) coordination numbers confirm the changes before and after photoswitching in the surface ligand conformation, which was correlated directly to variations in the catalytic application of the materials for nitrophenol reduction processes. In addition, the catalytic application of the materials was demonstrated to be significantly sensitive to the structure of the nitrophenol substrate used in the reaction, suggesting that changes in the reactivity are likely based upon the peptide conformation and substrate structure. Such results confirm that surface ligands can be remotely reconfigured on nanoparticle surfaces, providing pathways to apply such capabilities to a variety of applications beyond catalysis ranging from drug delivery to sensing.
Asunto(s)
Proteínas Inmovilizadas/química , Nanopartículas del Metal/química , Péptidos/química , Compuestos Azo/química , Compuestos Azo/efectos de la radiación , Catálisis , Oro/química , Proteínas Inmovilizadas/efectos de la radiación , Ligandos , Maleimidas/química , Maleimidas/efectos de la radiación , Nanopartículas del Metal/efectos de la radiación , Péptidos/efectos de la radiación , Conformación Proteica/efectos de la radiación , Propiedades de Superficie/efectos de la radiación , Rayos UltravioletaRESUMEN
A new series of pyrrole analogs were developed via the microwave irradiation synthesis. Consequently, got a high yield of the products. As pyrroles are familiar for showing various biological properties, all obtained compounds were screened for their antioxidant properties, most of the compounds showing significant activity. In fact, the motifs 5e, 5g, 5h and 5m showed outstanding antioxidant properties. Further, to enlighten the biologically energetic behavior underlying the antioxidant activity, compounds DFT studies were performed. Noteworthy results have been attained and the structure activity relationship (SAR) was discussed with the support of this results. It was found that highly biological active compounds exhibited a low HOMO-LUMO energy gap (Eg) and the high Eg value compounds show very low/negligible or inactive antioxidant activities. In other cases, compounds containing high HOMO energy levels also provide high antioxidant activity. The thought-provoking point of our results is that theoretical descriptors of the HOMO-LUMO energy gap and the highest occupied molecular orbital energy are important descriptors in the bioorganic research to support the biological experiments.
Asunto(s)
Depuradores de Radicales Libres/química , Maleimidas/química , Teoría Funcional de la Densidad , Depuradores de Radicales Libres/síntesis química , Depuradores de Radicales Libres/efectos de la radiación , Anhídridos Maleicos/química , Anhídridos Maleicos/efectos de la radiación , Maleimidas/síntesis química , Maleimidas/efectos de la radiación , Microondas , Modelos Químicos , Estructura Molecular , Fenilendiaminas/química , Fenilendiaminas/efectos de la radiación , Relación Estructura-ActividadRESUMEN
Relatively weak interactions between galectins and their potential ligands can hinder identification of physiological lectin ligands using conventional methods such as affinity purification. We have employed a combination of cysteine mutagenesis with chemical crosslinking using a photoactivatable sulfhydryl reagent benzophenone-4-maleimide to obtain a covalent complex between human galectin-1 and the model glycoprotein ligands asialofetuin and laminin which contain an N-acetyllactosamine structure. A crosslinked product was obtained only when galectin-1 with an introduced cysteine interacted with these glycoproteins via their carbohydrate moiety. This procedure should be useful for the detection of important, and as yet unidentified, ligands for galectins which cannot be currently detected because of their relatively weak interaction.
Asunto(s)
Amino Azúcares/química , Benzofenonas/química , Reactivos de Enlaces Cruzados/química , Cisteína/química , Galectina 1/química , Glicoproteínas/química , Maleimidas/química , Reactivos de Sulfhidrilo/química , Animales , Asialoglicoproteínas/química , Benzofenonas/efectos de la radiación , Bovinos , Cisteína/genética , Fetuínas , Galectina 1/genética , Humanos , Laminina/química , Lectinas , Maleimidas/efectos de la radiación , Procesos Fotoquímicos , Conejos , Reactivos de Sulfhidrilo/efectos de la radiación , alfa-Fetoproteínas/químicaRESUMEN
Azobenzene is a photochromic molecule that undergoes rapid and reversible isomerization between the cis- and trans-forms in response to ultraviolet (UV) and visible (VIS) light irradiation, respectively. Here, we introduced the sulfhydryl-reactive azobenzene derivative 4-phenylazophenyl maleimide (PAM) into the functional region of kinesin to reversibly regulate the ATPase activity of kinesin by photoirradiation. We prepared five kinesin motor domain mutants, A247C, L249C, A252C, G272C and S275C, which contained a single reactive cysteine residue in loops L11 and L12. These loops are considered to be key regions for the functioning of kinesin as a motor protein. PAM was stoichiometrically incorporated into the cysteine residues in the loops of the mutants. The PAM-modified S275C mutant exhibited reversible alterations in ATPase activity accompanied by cis-trans isomerization upon UV and VIS light irradiation. The ATPase activity exhibited by the cis-isomer of the PAM bound to the mutant was two times higher than that of the trans-isomer. Further, the PAM-modified L249C mutant exhibited reversible alterations in ATPase activity on UV-VIS light irradiation but exhibited the opposite effect on UV and VIS light irradiation. Using a photochromic azobenzene derivative, we have demonstrated that the ATPase activity of the motor protein kinesin is photoregulated.