Aqueous Solution Equilibria and Spectral Features of Copper Complexes with Tripeptides Containing Glycine or Sarcosine and Leucine or Phenylalanine

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dc.contributor.authorVicatos, Giselle M
dc.contributor.authorHammouda, Ahmed N
dc.contributor.authorAlnajjar, Radwan
dc.contributor.authorBonomo, Raffaele P
dc.contributor.authorValora, Gabriele
dc.contributor.authorBourne, Susan A
dc.contributor.authorJackson, Graham E
dc.date.accessioned2022-04-05T10:40:16Z
dc.date.available2022-04-05T10:40:16Z
dc.date.issued2022-01-10
dc.date.updated2022-01-20T15:24:25Z
dc.description.abstractCopper(II) complexes of glycyl-L-leucyl-L-histidine (GLH), sarcosyl-L-leucyl-L-histidine (Sar-LH), glycyl-L-phenylalanyl-L-histidine (GFH) and sarcosyl-L-phenylalanyl-L-histidine (Sar-FH) have potential anti-inflammatory activity, which can help to alleviate the symptoms associated with rheumatoid arthritis (RA). From pH 2&ndash;11, the MLH, ML, MLH<sub>-1</sub> and MLH<sub>-2</sub> species formed. The combination of species for each ligand was different, except at the physiological pH, where CuLH<sub>-2</sub> predominated for all ligands. The prevalence of this species was supported by EPR, ultraviolet-visible spectrophotometry, and mass spectrometry, which suggested a square planar CuN<sub>4</sub> coordination. All ligands have the same basicity for the amine and imidazole-N, but the methyl group of sarcosine decreased the stability of MLH and MLH<sub>-2</sub> by 0.1&ndash;0.34 and 0.46&ndash;0.48 log units, respectively. Phenylalanine increased the stability of MLH and MLH<sub>-2</sub> by 0.05&ndash;0.29 and 1.19&ndash;1.21 log units, respectively. For all ligands, <sup>1</sup>H NMR identified two coordination modes for MLH, where copper(II) coordinates via the amine-N and neighboring carbonyl-O, as well as via the imidazole-N and carboxyl-O. EPR spectroscopy identified the MLH, ML and MLH<sub>-2</sub> species for Cu-Sar-LH and suggested a CuN<sub>2</sub>O<sub>2</sub> chromophore for ML. DFT calculations with water as a solvent confirmed the proposed coordination modes of each species at the B3LYP level combined with 6-31++G**.
dc.identifierdoi: 10.3390/inorganics10010008
dc.identifier.apacitationVicatos, G. M., Hammouda, A. N., Alnajjar, R., Bonomo, R. P., Valora, G., Bourne, S. A., & Jackson, G. E. (2022). Aqueous Solution Equilibria and Spectral Features of Copper Complexes with Tripeptides Containing Glycine or Sarcosine and Leucine or Phenylalanine. <i>Inorganics</i>, 10(1), http://hdl.handle.net/11427/36268en_ZA
dc.identifier.chicagocitationVicatos, Giselle M, Ahmed N Hammouda, Radwan Alnajjar, Raffaele P Bonomo, Gabriele Valora, Susan A Bourne, and Graham E Jackson "Aqueous Solution Equilibria and Spectral Features of Copper Complexes with Tripeptides Containing Glycine or Sarcosine and Leucine or Phenylalanine." <i>Inorganics</i> 10, 1. (2022) http://hdl.handle.net/11427/36268en_ZA
dc.identifier.citationVicatos, G.M., Hammouda, A.N., Alnajjar, R., Bonomo, R.P., Valora, G., Bourne, S.A. & Jackson, G.E. 2022. Aqueous Solution Equilibria and Spectral Features of Copper Complexes with Tripeptides Containing Glycine or Sarcosine and Leucine or Phenylalanine. <i>Inorganics.</i> 10(1) http://hdl.handle.net/11427/36268en_ZA
dc.identifier.ris TY - Journal Article AU - Vicatos, Giselle M AU - Hammouda, Ahmed N AU - Alnajjar, Radwan AU - Bonomo, Raffaele P AU - Valora, Gabriele AU - Bourne, Susan A AU - Jackson, Graham E AB - Copper(II) complexes of glycyl-L-leucyl-L-histidine (GLH), sarcosyl-L-leucyl-L-histidine (Sar-LH), glycyl-L-phenylalanyl-L-histidine (GFH) and sarcosyl-L-phenylalanyl-L-histidine (Sar-FH) have potential anti-inflammatory activity, which can help to alleviate the symptoms associated with rheumatoid arthritis (RA). From pH 2&ndash;11, the MLH, ML, MLH<sub>-1</sub> and MLH<sub>-2</sub> species formed. The combination of species for each ligand was different, except at the physiological pH, where CuLH<sub>-2</sub> predominated for all ligands. The prevalence of this species was supported by EPR, ultraviolet-visible spectrophotometry, and mass spectrometry, which suggested a square planar CuN<sub>4</sub> coordination. All ligands have the same basicity for the amine and imidazole-N, but the methyl group of sarcosine decreased the stability of MLH and MLH<sub>-2</sub> by 0.1&ndash;0.34 and 0.46&ndash;0.48 log units, respectively. Phenylalanine increased the stability of MLH and MLH<sub>-2</sub> by 0.05&ndash;0.29 and 1.19&ndash;1.21 log units, respectively. For all ligands, <sup>1</sup>H NMR identified two coordination modes for MLH, where copper(II) coordinates via the amine-N and neighboring carbonyl-O, as well as via the imidazole-N and carboxyl-O. EPR spectroscopy identified the MLH, ML and MLH<sub>-2</sub> species for Cu-Sar-LH and suggested a CuN<sub>2</sub>O<sub>2</sub> chromophore for ML. DFT calculations with water as a solvent confirmed the proposed coordination modes of each species at the B3LYP level combined with 6-31++G**. DA - 2022-01-10 DB - OpenUCT DP - University of Cape Town IS - 1 J1 - Inorganics LK - https://open.uct.ac.za PY - 2022 T1 - Aqueous Solution Equilibria and Spectral Features of Copper Complexes with Tripeptides Containing Glycine or Sarcosine and Leucine or Phenylalanine TI - Aqueous Solution Equilibria and Spectral Features of Copper Complexes with Tripeptides Containing Glycine or Sarcosine and Leucine or Phenylalanine UR - http://hdl.handle.net/11427/36268 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/36268
dc.identifier.urihttps://doi.org/10.3390/inorganics10010008
dc.identifier.vancouvercitationVicatos GM, Hammouda AN, Alnajjar R, Bonomo RP, Valora G, Bourne SA, et al. Aqueous Solution Equilibria and Spectral Features of Copper Complexes with Tripeptides Containing Glycine or Sarcosine and Leucine or Phenylalanine. Inorganics. 2022;10(1) http://hdl.handle.net/11427/36268.en_ZA
dc.publisherMultidisciplinary Digital Publishing Institute
dc.rights.licensehttps://creativecommons.org/licenses/by/4.0/
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/
dc.sourceInorganics
dc.source.journalissue1
dc.source.journalvolume10
dc.source.urihttps://www.mdpi.com/journal/inorganics
dc.titleAqueous Solution Equilibria and Spectral Features of Copper Complexes with Tripeptides Containing Glycine or Sarcosine and Leucine or Phenylalanine
dc.typeJournal Article
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