- Five- and six-membered nitrogen-containing compounds as selective carbonic anhydrase activators
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It has been proven that specific isoforms of human carbonic anhydrase (hCA) are able to fine-tune physiological pathways connected to signal processing, and that decreased CAs expression negatively influences cognition, leading to mental retardation, Alzheimer’s disease, and aging-related cognitive dysfunctions. For this reason, a small library of natural and synthetic nitrogen containing cyclic derivatives was assayed as activators of four human isoforms of carbonic anhydrase (hCA I, II, IV and VII). Most of the compounds activated hCA I, IV and VII in the micromolar range, with KAs ranging between 3.46 and 80.5 μM, whereas they were not active towards hCA II (KAs > 100 μM). Two natural compounds, namely L-(+)-ergothioneine (1) and melatonin (2), displayed KAs towards hCA VII in the nanomolar range after evaluation by a CO2 hydration method in vitro, showing a rather efficient and selective activation profile with respect to histamine, used as a reference compound. Corroborated with the above in vitro findings, a molecular modelling in silico approach has been performed to correlate these biological data, and to elucidate the binding interaction of these activators within the enzyme active site.
- Mollica, Adriano,Macedonio, Giorgia,Stefanucci, Azzurra,Carradori, Simone,Akdemir, Atilla,Angeli, Andrea,Supuran, Claudiu T.
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- Phenylalanine-containing cyclic dipeptides-the lowest molecular weight hydrogelators based on unmodified proteinogenic amino acids
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Cyclic dipeptides (diketopiperazines-DKPs) that are based on the proteinogenic amino acid phenylalanine in combination with serine, cysteine, glutamate, histidine and lysine are described as simple and remarkable low molecular weight hydrogelators. Blends
- Kleinsmann, Alexander J.,Nachtsheim, Boris J.
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supporting information
p. 7818 - 7820
(2013/09/02)
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- Biomimetic catalysis of diketopiperazine and dipeptide syntheses
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Modular supramolecular catalysts with a coiled-coil peptide scaffold, designed to mimic nonribosomal peptide synthetases, catalyze the formation of diketopiperazines and linear dipeptides for several aminoacyl substrates (see scheme). The nature of the ac
- Huang, Zheng-Zheng,Leman, Luke J.,Ghadiri, M. Reza
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supporting information; experimental part
p. 1758 - 1761
(2009/02/06)
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- Thermodynamic and (1)H NMR Study of Proton Complex Formation of Histidine-containing Cyclodipeptides in Aqueous Solution
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A thermodynamic and (1)H NMR study of proton complex formation in aqueous solution of some L-histidine-containing cyclic L-dipeptides has been carried out.The enthalpic and entropic changes associated with protonation of the cyclodipeptides, obtained by potentiometric and calorimetric measurements, together with the (1)H NMR data and NOESY experiments, enable the role played by non-covalent interactions in proton complex formation to be assessed.In addition, a comparison with c(Gly-His) permits the influence of side-chain residues on the conformation of protonated species to be observed.
- Arena, Giuseppe,Impellizzeri, Giuseppe,Maccarrone, Giuseppe,Pappalardo, Giuseppe,Sciotto, Domenico,Rizzarelli, Enrico
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p. 371 - 376
(2007/10/02)
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- The Cyclic Dipeptide cyclo as a Catalyst for Asymmetric Addition of Hydrogen Cyanide to Aldehydes
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cyclo (cyclo, 1) catalyzes the addition of hydrogen cyanide to benzaldehyde in toluene at -20 deg C to afford (R)-mandelonitrile with enantiomeric excess of 97 percent in high yield. cyclo gives (S)-mandelonitrile. cyclo (1) exhibits a broad substrate specificity, and a variety of aldehydes (3a-r) such as m-methoxybenzaldehyde (3c), 6-methoxy-2-naphthaldehyde (3k), and isobutyraldehyde (3o) similarly afforded the corresponding cyanohydrins with high enantiopurities (97 percent ee for 3c, 93 percent ee for 3k, 71 percent ee for 3o). (R)-Mandelonitrile thus obtained was successfully converted to various chiral synthons such as mandelic acid (7), methyl mandelate (8), and 2-amino-1-phenylethanol (9) without any racemization.
- Tanaka, Kenzo,Mori, Atsunori,Inoue, Shohei
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p. 181 - 185
(2007/10/02)
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- Cyclo-((S)-leucyl-(S)-histidyl). A Catalyst for Asymmetric Addition of Hydrogen Cyanide to Aldehydes
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Asymmetric addition of hydrogen cyanide to various aldehydes in the presence of a catalytic amount of cyclo-((S)-leucyl-(S)-histidyl) affords the corresponding cyanohydrins in moderate to good optical yields.The reaction of benzaldehyde with hydrogen cyanide gives (S)-2-hydroxy-2-phenylacetonitrile (85percent, 55percent ee) whose stereochemistry is found to be opposite to our previous result using cyclo-((S)-phenylalanyl-(S)-histidyl).
- Mori, Atsunori,Ikeda, Yoshitaka,Kinoshita, Koichi,Inoue, Shohei
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p. 2119 - 2122
(2007/10/02)
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- A Mechanism for bitter Taste Sensibility in Peptides
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To estimate the steric distance between the bitter taste determinant sites in peptides, some cyclic dipeptides, amino acid anilides, amino acid cyclohexylamides, and benzoyl amino acids were synthesized and their tastes were evaluated.The diketopiperazine ring of cyclic dipeptides acted as a bitter taste determinant site due to its hydrophobicity.The steric distance between 2 sites was estimated as 4.1 Angstroem from the molecule models of cyclic dipeptides composed of typical amino acids in the bitter peptides.Due to the hypothesis of two bitter taste determinant sites, which bind with the bitter taste receptor via a "binding unit" and a "stimulating unit," a mechanism for the bitterness in peptides was postulated.
- Ishibashi, Norio,Kouge, Katsushige,Shinoda,Ichizo,Kanehisa, Hidenori,Okai, Hideo
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p. 819 - 828
(2007/10/02)
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- Hydrolysis of Active Esters of Aliphatic Carboxylic Acids with Cyclic Dipeptide Catalysts Consisting of L-Histidine and Different Aliphatic α-Amino Acids
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The hydrolyses of a series of p-nitrophenyl carboxylates with different acyl chains were investigated at 25 deg C, pH 7.8 using cyclic dipeptides as catalyst.Consequently, cyclo(-D-Leu-L-His) and cyclo(-D-Val-L-His-) were found to be specifically effective catalyst for the hydrolysis of p-nitrophenyl laurate.These trans (D-L-type) cyclic dipeptides were much more efficient catalysts than their diastereoisomers, and were more reactive than imidazole, despite the fact that the former are less basic than latter.The conformation of the cyclic peptides in solution was investigated using proton magnetic spectroscopy and the relationship between conformation and catalytic activity was investigated.Consequently, it was found that the hydrophobic interaction between a catalyst and a substrate and the stereochemical fit for the cooperation of functional groups in the intramolecular nucleophilic catalysis are very important in order to attain a highly efficient catalysis.It was also found that the functional groups should have a certain size and flexibility in order to realize an effective stereochemical fit between functional groups of catalysts and substrates.
- Masuda, Yoshihiko,Tanihara, Masao,Imanishi, Yukio,Higashimura, Toshinobu
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p. 497 - 504
(2007/10/02)
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