- Superactivity of MOF-808 toward Peptide Bond Hydrolysis
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MOF-808, a Zr(IV)-based metal-organic framework, has been proven to be a very effective heterogeneous catalyst for the hydrolysis of the peptide bond in a wide range of peptides and in hen egg white lysozyme protein. The kinetic experiments with a series of Gly-X dipeptides with varying nature of amino acid side chain have shown that MOF-808 exhibits selectivity depending on the size and chemical nature of the X side chain. Dipeptides with smaller or hydrophilic residues were hydrolyzed faster than those with bulky and hydrophobic residues that lack electron rich functionalities which could engage in favorable intermolecular interactions with the btc linkers. Detailed kinetic studies performed by 1H NMR spectroscopy revealed that the rate of glycylglycine (Gly-Gly) hydrolysis at pD 7.4 and 60 °C was 2.69 × 10-4 s-1 (t1/2 = 0.72 h), which is more than 4 orders of magnitude faster compared to the uncatalyzed reaction. Importantly, MOF-808 can be recycled several times without significantly compromising the catalytic activity. A detailed quantum-chemical study combined with experimental data allowed to unravel the role of the {Zr6O8} core of MOF-808 in accelerating Gly-Gly hydrolysis. A mechanism for the hydrolysis of Gly-Gly by MOF-808 is proposed in which Gly-Gly binds to two Zr(IV) centers of the {Zr6O8} core via the oxygen atom of the amide group and the N-terminus. The activity of MOF-808 was also demonstrated toward the hydrolysis of hen egg white lysozyme, a protein consisting of 129 amino acids. Selective fragmentation of the protein was observed with 55% yield after 25 h under physiological pH.
- Ly, Hong Giang T.,Fu, Guangxia,Kondinski, Aleksandar,Bueken, Bart,De Vos, Dirk,Parac-Vogt, Tatjana N.
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p. 6325 - 6335
(2018/05/14)
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- EPIDITHIODIOXOPIPERAZINE COMPOUND OR ITS DERIVATIVES, AND THE USE THEREOF
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The present invention relates to an epidithiodioxopiperazine derivative represented by the Chemical Formula 1 or its reduced derivative; a method for preparing a compound represented by Chemical Formula 1 having improved intracellular permeability and mim
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Paragraph 387; 392-394
(2014/12/12)
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- Method for Preparation of Piperazindione Derivatives
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A process for preparing piperazinedione derivatives of the formula I in which R1 is hydrogen, alkyl, alkenyl, alkynyl and alkylcarbonyl,R2 is hydrogen, alkyl, alkenyl, C3-C4-alkynyl and C(═O)R11,Rsup
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Page/Page column 9
(2011/06/26)
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- Cyclization-activated prodrugs. Synthesis, reactivity and toxicity of dipeptide esters of paracetamol
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Dipeptide esters of paracetamol were prepared in high yields. These compounds are quantitatively hydrolyzed to paracetamol and corresponding 2,5-diketopiperazines at pH 7.4 and 37°C. The reactivity is increased in sarcosine and proline peptides and decreased by bulky side chains at both the N- and C-terminal residues of the dipeptide carrier. Moreover, dipeptide esters of paracetamol did not affect the levels of hepatic glutathione. Thus, dipeptides seem promising candidates as carriers for cyclization-activated prodrugs.
- Santos, Cledir,Mateus, Maria Luisa,Dos Santos, Ana Paula,Moreira, Rui,De Oliveira, Eliandre,Gomes, Paula
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p. 1595 - 1598
(2007/10/03)
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- Comparative study of synthetic approaches to 1- arylmethylenepyrazino[2,1-b]quinazoline-3,6-diones
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The transformation of 3-arylmethylenepiperazine-2,5-diones (1) into 1- arylmethylene-2,4-dihydro-1H-pyrazino[2,1-b]quinazoline-3,6-diones (2) was studied. Four synthetic methods were compared, namely direct condensation with the product of the reaction be
- Cledera, Pilar,Avendano, Carmen,Menendez, J. Carlos
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p. 12349 - 12360
(2007/10/03)
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- THE "GAS-SOLID-PHASE" 2,5-DIOXOPIPERAZINE SYNTHESIS. CYCLIZATION OF VAPOROUS DIPEPTIDES ON SILICA SURFACE
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The "gas-solid-phase" method is used for the preparation of both symmetric and asymmetric 2,5-dioxopiperazines via cyclization of vaporous linear dipeptides in the presence of silica.
- Basiuk, Vladimir,Gromovoy, Taras Yu.
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p. 461 - 466
(2007/10/02)
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- N-Hydroxy Amides. Part 6. Synthesis and Spectroscopic Properties of 1-Hydroxypiperazine-2,5-diones
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1-Hydroxypiperazine-2,5-diones (3a-f) are prepared in good yields, starting with Boc-L-amino acids and N-benzyloxyglycine methyl ester.The rate of cyclisation for N-hydroxy and N-benzyloxydipeptide methyl esters are 38-77 times as large as that of phenyla
- Akiyama, Masayasu,Katoh, Akira,Tsuchiya, Yuko
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p. 235 - 239
(2007/10/02)
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- First-Order Rate Constans for the Racemization of Each Component in a Mixture of Isomeric Dipeptides and their Diketopiperazines
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L-Alanylglycine (L-Ala-Gly), glycyl-L-alanine (Gly-L-Ala), and c-L-Ala-Gly were racemized at 120 deg C in aqueous phosphate-buffered solutions at pH 8.0, a pH value near maximum racemization.The kinetics were followed by regression analysis.The racemization of Ala-Gly and Gly-Ala closelly followed reversible first-order kinetics.The initial rate of racemisation of DKP was fast but soon slowed, likely because of hydrolysis to the dipeptides.The resulting rate was similar to that of the dipeptides.The observed racemization rate constans of the dipeptides and DKP were shown to be independent of the concentration of the peptides and the concetration of buffer.Component isolation studies using preparative TLC and chiral-phase GC analysis, coupled with computer analysis, showed an equilibrium existing between Ala-Gly, Gly-Ala, and DKP and the individual rates of racemization.At equilibrium, the mole fractions are as follows: Ala-Gly, 0.57; DKP, 0.22; Gly-Ala, 0.21.The rate constant for racemization of DKP was only 2 times that of Gly-Ala and 7 times the rate of Ala-Gly.Ala-Gly racemized 20 times and Gly-Ala 66 times faster than free alanine.The results support the influence of neighboring groups in the racemization of dipeptides.Factors that contribute to the rapid racemization (epimerization) are discussed.
- Smith, Grant Gill,Baum, Rocky
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p. 2248 - 2255
(2007/10/02)
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- Neighboring Residue Effects: Evidence for Intramolecular Assistance to Racemization or Epimerization of Dipeptide Residues
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Dipeptides, their methyl esters, diketopiperazines (DKP), and N-substituted derivatives were racemized at high temperatures (approximately 120 deg C) in aqueous phosphate buffered solutions at pH values close to pH of maximum racemization (approximately 8).The racemization of the dipeptides Ala-Gly and Gly-Ala followed reversible first-order kinetics.The initial rate of racemization of DKP was very fast but soon slowed down, supposedly due to hydrolysis.The resulting rate was similar to that of the dipeptides.Esters of dipeptides followed racemization patterns similar to DKP.The racemization rate constants of the dipeptides studied were shown to be independent of the concentration of the dipeptide and the concentration of buffer.A carboxy-terminal proline residue greatly increased the rate of racemization (epimerization) of the amino-terminal residue.Increasing the basicity of the N-terminal amino acid residue increased the rate of racemization (or epimerization) of the C-terminal residue unless the C-terminal was sterically hindered as the Ile and Val.Decreasing the basicity of the N-terminal amino acid residue decreased racemization or epimerization for nonhindered C-terminal amino acids.These results support the influence of neighboring groups in the racemization or epimerization of dipeptides.DKP formation is a competing reaction allowing racemization or epimerization in dipeptides.Dipeptide racemization or epimerization is proposed to be the result of combination of intramolecular base assistance and DKP formation.
- Smith, Grant Gill,Evans, Robert C.,Baum, Rocky
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p. 7327 - 7332
(2007/10/02)
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- The Absolute Configurations of (+)- and (-)-2-Methylpiperazines and their N-Methyl Derivatives.
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S(-)-2-Methylpiperazinium dichloride was prepared by reduction of S(-)-3-methyl-2,5-dioxopiperazine (from glycyl-S-alanine) which established its absolute configuration.This dichloride and its enantiomer, R(+)-2-methylpiperazinium dichloride, were obtained in less optically pure forms by recrystallization of the diastereomeric RS-2-methylpiperazinium 2R,3R-di-O-benzoyltartrate salts followed by decomposition with a base.They were converted into S(+)- and R(-)-1,2,4-trimethylpiperazinium dichloride, S(+)- and R(-)-1,2,4,4-tetramethylpiperazinium iodide and S(+)- and R(-)-1,1,2,4,4-pentamethylpiperazinium diiodide.
- Armarego, Wilfred L. F.,Schou, Henning,Waring, Paul
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p. 1951 - 1966
(2007/10/02)
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