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Synthesis of Oligomeric and Monomeric Functionalized Graphene Oxides and a Comparison of Their Abilities to Perform as Protein Ligands and Enzyme Inhibitors.

ABSTRACT: Graphene oxide (GO) is a versatile, monomolecular layered nanomaterial that possesses various oxygen-containing functionality on its large surface. These characteristics allow GO to interact with a variety of materials and to be applied towards a number of areas. The strength and selectivity of these interactions can be improved significantly through further functionalization. In this paper, we describe the functionalization of GO and its application as a protein ligand and an enzyme inhibitor. The work reported in this paper details how chymotrypsin inhibition can be improved using GO functionalized with a monomeric and oligomer layer of tyrosine. The results indicated that the mono- and oligo-functionalized systems performed extremely well, with Ki values nearly four times better than GO alone. Our original premise was that the oligomeric system would bind better because of the length of the oligomeric arms and potential for a high degree of flexibility. However, the results clearly showed that the shorter monomeric system was the better ligand/inhibitor. This was due to weaker intramolecular interactions between the aromatic side chains of tyrosine and the aromatic surface of GO. Although these are possible for both systems, they are cooperative and therefore stronger for the oligomeric functionalized GO. As such, the protein must compete and overcome these cooperative intramolecular interactions before it can bind to the functionalized GO, whereas the tyrosines on the surface of the monomeric system interact with the surface of GO through a significantly weaker monovalent interaction, but interact cooperatively with the protein surface.

SUBMITTER: Aziz AA

PROVIDER: S-EPMC7007006 | biostudies-literature | 2019 Dec

REPOSITORIES: biostudies-literature

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Synthesis of Oligomeric and Monomeric Functionalized Graphene Oxides and a Comparison of Their Abilities to Perform as Protein Ligands and Enzyme Inhibitors.

Aziz Azrah Abdul AA Twyman Lance J LJ

ACS applied materials & interfaces 20191119 48

Graphene oxide (GO) is a versatile, monomolecular layered nanomaterial that possesses various oxygen-containing functionality on its large surface. These characteristics allow GO to interact with a variety of materials and to be applied towards a number of areas. The strength and selectivity of these interactions can be improved significantly through further functionalization. In this paper, we describe the functionalization of GO and its application as a protein ligand and an enzyme inhibitor. ...[more]

PMID: 31697476

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Project description:Background: In a recent intervention study, the daily supplementation with 200mg monomeric and oligomeric flavanols (MOF) from grape seeds for 8 weeks revealed a vascular health benefit in male smokers. The objective of the present study was to determine the impact of MOF consumption on the gene expression profile of leukocytes and to assess changes in DNA methylation. Methodology/Principal Findings: Gene expression profiles were determined using whole genome microarrays (Agilent) and DNA methylation was assessed using HumanMethylation450 BeadChips (Illumina). MOF significantly modulated the expression of 869 genes. The majority of the affected genes are involved in chemotaxis, cell adhesion, cell infiltration or cytoskeleton organisation, suggesting lower immune cell adhesion to endothelial cells. This was corroborated by in vitro experiments showing that MOF exposure of monocytes attenuates their adhesion to TNFα-stimulated endothelial cells. Nuclear factor-kappa B reporter gene assays confirmed that MOF decrease the activity of NF-κB. Strong inter-individual variability in the leukocytes DNA methylation was observed. As a consequence, on group level, changes due to MOF supplementation could not be found. However, in individuals, significant changes in DNA methylation of genes involved in leukocyte rolling, adhesion and cytoskeleton remodelling were seen. At the group level, the variation in DNA methylation related to life style and clinical parameters appeared to overrule the magnitude of effects of supplementation with MOF. Conclusion: Our study revealed that regular consumption of MOF modulates the expression of genes in immune cells which, however, cannot be correlated to alterations in the DNA methylome. Remarkably, at the individual level, genes related to leukocyte adhesion pathways present complex variation in DNA methylation. As such, the individual transcriptional and epigenetic modulation of genes involved in early manifestation of cardiovascular diseases constitutes important subcellular mechanisms by which MOF promote vascular health in humans.

Project description:Background: In a recent intervention study, the daily supplementation with 200mg monomeric and oligomeric flavanols (MOF) from grape seeds for 8 weeks revealed a vascular health benefit in male smokers. The objective of the present study was to determine the impact of MOF consumption on the gene expression profile of leukocytes and to assess changes in DNA methylation. Methodology/Principal Findings: Gene expression profiles were determined using whole genome microarrays (Agilent) and DNA methylation was assessed using HumanMethylation450 BeadChips (Illumina). MOF significantly modulated the expression of 869 genes. The majority of the affected genes are involved in chemotaxis, cell adhesion, cell infiltration or cytoskeleton organisation, suggesting lower immune cell adhesion to endothelial cells. This was corroborated by in vitro experiments showing that MOF exposure of monocytes attenuates their adhesion to TNFM-NM-1-stimulated endothelial cells. Nuclear factor-kappa B reporter gene assays confirmed that MOF decrease the activity of NF-M-NM-:B. Strong inter-individual variability in the leukocytes DNA methylation was observed. As a consequence, on group level, changes due to MOF supplementation could not be found. However, in individuals, significant changes in DNA methylation of genes involved in leukocyte rolling, adhesion and cytoskeleton remodelling were seen. At the group level, the variation in DNA methylation related to life style and clinical parameters appeared to overrule the magnitude of effects of supplementation with MOF. Conclusion: Our study revealed that regular consumption of MOF modulates the expression of genes in immune cells which, however, cannot be correlated to alterations in the DNA methylome. Remarkably, at the individual level, genes related to leukocyte adhesion pathways present complex variation in DNA methylation. As such, the individual transcriptional and epigenetic modulation of genes involved in early manifestation of cardiovascular diseases constitutes important subcellular mechanisms by which MOF promote vascular health in humans. Two-colors experiment, 7 volunteers : blood samples of 7 men, before and after an intervention of 8 weeks with daily intake of MOF (14 samples).

Dataset Information

Synthesis of Oligomeric and Monomeric Functionalized Graphene Oxides and a Comparison of Their Abilities to Perform as Protein Ligands and Enzyme Inhibitors.

Publications

Synthesis of Oligomeric and Monomeric Functionalized Graphene Oxides and a Comparison of Their Abilities to Perform as Protein Ligands and Enzyme Inhibitors.

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