scholarly journals Catalytic Hydrolysis of Phosphate Monoester by Supramolecular Complexes Formed by the Self-Assembly of a Hydrophobic Bis(Zn2+-cyclen) Complex, Copper, and Barbital Units That Are Functionalized with Amino Acids in a Two-Phase Solvent System

Micromachines ◽  
2019 ◽  
Vol 10 (7) ◽  
pp. 452
Author(s):  
Yuya Miyazawa ◽  
Akib Bin Rahman ◽  
Yutaka Saga ◽  
Hiroki Imafuku ◽  
Yosuke Hisamatsu ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Amino Acids ◽  
Active Site ◽  
Self Assembly ◽  
Hydrolytic Activity ◽  
Solvent System ◽  
Supramolecular Complexes ◽  
Artificial System ◽  
Two Phase ◽  
Hydrolysis Of

We previously reported on the preparation of supramolecular complexes by the 2:2:2 assembly of a dinuclear Zn2+-cyclen (cyclen = 1,4,7,10-tetraazacyclododecane) complex having a 2,2′-bipyridyl linker equipped with 0~2 long alkyl chains (Zn2L1~Zn2L3), 5,5-diethylbarbituric acid (Bar) derivatives, and a copper(II) ion (Cu2+) in aqueous solution and two-phase solvent systems and their phosphatase activities for the hydrolysis of mono(4-nitrophenyl) phosphate (MNP). These supermolecules contain Cu2(μ-OH)2 core that mimics the active site of alkaline phosphatase (AP), and one of the ethyl groups of the barbital moiety is located in close proximity to the Cu2(μ-OH)2 core. The generally accepted knowledge that the amino acids around the metal center in the active site of AP play important roles in its hydrolytic activity inspired us to modify the side chain of Bar with various functional groups in an attempt to mimic the active site of AP in the artificial system, especially in two-phase solvent system. In this paper, we report on the design and synthesis of new supramolecular complexes that are prepared by the combined use of bis(Zn2+-cyclen) complexes (Zn2L1, Zn2L2, and Zn2L3), Cu2+, and Bar derivatives containing amino acid residues. We present successful formation of these artificial AP mimics with respect to the kinetics of the MNP hydrolysis obeying Michaelis–Menten scheme in aqueous solution and a two-phase solvent system and to the mode of the product inhibition by inorganic phosphate.

Enzymatic hydrolysis of β-lactam antibiotics at low pH in a two-phase "aqueous solution - water-immiscible organic solvent" system

2002 ◽  
Vol 80 (6) ◽  
pp. 699-707 ◽  
Author(s):  
Ghermes G Chilov ◽  
Vytas K Švedas
Keyword(s):  
Aqueous Solution ◽  
Enzymatic Hydrolysis ◽  
Organic Solvent ◽  
Solvent System ◽  
Low Ph ◽  
Thermodynamic Evaluation ◽  
Two Phase ◽  
Suggested Approach ◽  
Hydrolysis Of ◽  
Organic Solvent System

The application of the two-phase "aqueous solution – water-immiscible organic solvent" system is suggested not for effective biocatalytic synthesis, but for hydrolytic purposes. Enzymatic hydrolysis of benzylpenicillin and N-phenylacetamidodesacetoxycephalosporanic acid to corresponding antibiotic nuclei 6-aminopenicillanic and 7-aminodesacetoxycephalosporanic acids in a two-phase water–butylacetate system at pH 3–4 is proposed as an alternative to the biocatalytic hydrolysis in an alkaline medium. An experimental study has been performed and a model has been developed, which describes the influence of pH, phase volume ratio, thermodynamic constants, and initial antibiotic concentration on the effectiveness of their hydrolysis in a two-phase "aqueous solution – water-immiscible organic solvent" system. The thermodynamic evaluation of penicillin G and 7-phenylacetamidodesacetoxycephalosporanic acid hydrolysis at low pH in a two-phase aqueous solution – water-immiscible organic solvent system has demonstrated high practical potential. The suggested approach allows for the exclusion of several technological steps during the transformation of natural β-lactam antibiotics to their semi-synthetic analogues: alkaline extraction of the biosynthetic antibiotic from butylacetate followed by its enzymatic hydrolysis at pH 7.5–8.0 and further acidification of the reaction mixture, which results in the precipitation of the antibiotic nucleus. Experimental observations also revealed a specific feature of this process: the kinetic supersaturation of the antibiotic nucleus slows down the attainment of the equilibrium, which should be taken into account when further developing this approach.Key words: enzymatic hydrolysis, β-lactam antibiotic nuclei, two-phase systems, supersaturation, penicillin acylase.

Iron(III) complexes of DL-methionine

1972 ◽  
Vol 25 (2) ◽  
pp. 421 ◽  
Author(s):  
EJ Halbert ◽  
MJ Rogerson
Keyword(s):  
Aqueous Solution ◽  
Amino Acids ◽  
Large Excess ◽  
Ph Titration ◽  
Oxidation Reduction ◽  
Infrared Studies ◽  
Rapid Hydrolysis ◽  
Iron Analysis ◽  
Hydrolysis Of ◽  
Made In

Few iron(111) complexes of amino acids have been isolated although attempts have been made to measure their stabilities in solution. Iron(111) in the presence of various amino acids showed no complex formation during pH titration in aqueous solution. Using oxidation-reduction and spectrophotometric techniques Perrin measured the stabilities of 1 : 1 complexes of iron(111) with different amino acids in solutions of low pH. Rapid hydrolysis of iron(111) occurred when the pH was increased even in the presence of a large excess of amino acids. Bielig and Bayer reported the isolation of a bis-complex of iron(111) and methionine prepared in aqueous solution. McAuliffe, Quagliano, and Vallarinoe reported a tris-complex made in ethanol, though their iron analysis was not consistent with the required structure. In both cases magnetic and infrared studies were used to characterize the products. Our attempts to repeat these preparations were unsuccessful. This paper describes the preparation of two 1 : 1 complexes of methionine and iron(111) and an investigation of their properties by analysis of infrared, magnetic, and N.M.R. measurements.

scholarly journals Substituent Effects on Carbon Acidity in Aqueous Solution and at Enzyme Active Sites

Synlett ◽  
2017 ◽  
Vol 28 (12) ◽  
pp. 1407-1421 ◽  
Author(s):  
John Richard ◽  
Tina Amyes
Keyword(s):  
Aqueous Solution ◽  
Amino Acids ◽  
Active Site ◽  
Active Sites ◽  
Substituent Effects ◽  
Imidazolium Cations ◽  
Enzyme Active Sites ◽  
Iminium Cations ◽  
Carbon Acids

Methods are described for the determination of pK as for weak carbon acids in water. The application of these methods to the determination of the pK as for a variety of carbon acids including nitriles, imidazolium cations, amino acids, peptides and their derivatives and, α-iminium cations is presented. The substituent effects on the acidity of these different classes of carbon acids are discussed, and the relevance of these results to catalysis of the deprotonation of amino acids by enzymes and by pyridoxal 5′-phosphate is reviewed. The procedure for estimating the pK a of uridine 5′-phosphate for C-6 deprotonation at the active site of orotidine 5′-phosphate decarboxylase is described, and the effect of a 5-F substituent on carbon acidity of the enzyme-bound substrate is discussed.1 Introduction2 The Carbon Acidity of Ethyl Thioacetate3 The Carbon Acidity of Carboxylic Acid Derivatives4 The Carbon Acidity of Imidazolium Cations5 The α-Carbon Acidity of Amino Acids, Peptides and Their Derivatives6 Electrophilic Catalysis of Deprotonation of Amino Acids: The α-Carbon Acidity of Iminium Cations7 pK as for Carbon Acids at Enzyme Active Sites8 Concluding Remarks

Hydrolysis of Cinnamaldehyde in Aqueous Solution at Room Temperature Catalyzed by Amino Acids

2012 ◽  
Vol 512-515 ◽  
pp. 2361-2365 ◽  
Author(s):  
Lu Lu Huang ◽  
Xing Dong Yao ◽  
Yong Peng An ◽  
Cai Hua Peng
Keyword(s):  
Aqueous Solution ◽  
Amino Acids ◽  
Reaction Time ◽  
Room Temperature ◽  
Spectroscopic Analysis ◽  
Buffer Concentration ◽  
Hydrolysis Of

The hydrolysis of cinnamaldehyde in aqueous solution catalyzed by amino acids has been investigated. Eight amino acids e.g. glycine, proline etc. have been employed as the small molecular organocatalysts. The effect of reaction time, temperature, buffer concentration on the reaction has been studied. Spectroscopic analysis indicated the reaction product is 3-hydroxy-3-phenylpropanal.

scholarly journals Molecular and Physiological Role of the Trehalose-Hydrolyzing α-Glucosidase from Thermus thermophilus HB27

2008 ◽  
Vol 190 (7) ◽  
pp. 2298-2305 ◽  
Author(s):  
Susana Alarico ◽  
Milton S. da Costa ◽  
Nuno Empadinhas
Keyword(s):  
Amino Acids ◽  
Minimal Medium ◽  
Thermus Thermophilus ◽  
Physiological Role ◽  
Hydrolytic Activity ◽  
Recombinant Enzyme ◽  
New Feature ◽  
Hydrolysis Of ◽  
Reciprocal Replacement

ABSTRACT Trehalose supports the growth of Thermus thermophilus strain HB27, but the absence of obvious genes for the hydrolysis of this disaccharide in the genome led us to search for enzymes for such a purpose. We expressed a putative α-glucosidase gene (TTC0107), characterized the recombinant enzyme, and found that the preferred substrate was α,α-1,1-trehalose, a new feature among α-glucosidases. The enzyme could also hydrolyze the disaccharides kojibiose and sucrose (α-1,2 linkage), nigerose and turanose (α-1,3), leucrose (α-1,5), isomaltose and palatinose (α-1,6), and maltose (α-1,4) to a lesser extent. Trehalose was not, however, a substrate for the highly homologous α-glucosidase from T. thermophilus strain GK24. The reciprocal replacement of a peptide containing eight amino acids in the α-glucosidases from strains HB27 (LGEHNLPP) and GK24 (EPTAYHTL) reduced the ability of the former to hydrolyze trehalose and provided trehalose-hydrolytic activity to the latter, showing that LGEHNLPP is necessary for trehalose recognition. Furthermore, disruption of the α-glucosidase gene significantly affected the growth of T. thermophilus HB27 in minimal medium supplemented with trehalose, isomaltose, sucrose, or palatinose, to a lesser extent with maltose, but not with cellobiose (not a substrate for the α-glucosidase), indicating that the α-glucosidase is important for the assimilation of those four disaccharides but that it is also implicated in maltose catabolism.

scholarly journals Vanadium(III) binding strengths of small biomolecules

2005 ◽  
Vol 77 (9) ◽  
pp. 1583-1594 ◽  
Author(s):  
Péter Buglyó ◽  
Eszter Márta Nagy ◽  
Imre Sóvágó
Keyword(s):  
Aqueous Solution ◽  
Amino Acids ◽  
Ionic Strength ◽  
Metal Ion ◽  
Donor Ligands ◽  
Spectroscopic Techniques ◽  
Hydroxo Complexes ◽  
Similarities And Differences ◽  
Small Biomolecules ◽  
Hydrolysis Of

The hydrolysis of vanadium(III) and the complex formation reactions between V(III) and weakly coordinating [glycine (GLY), DL-aspartic acid (ASP), D-penicillamine (PEN), DL-histidine (HIS)] or strongly coordinating [N,O] donor [picolinic (PIC) or 6-methylpicolinic acid (MePIC)] and [O,O] donor [maltol (MALT), 1,2-dimethyl-3-hydroxy-4-(1H)-pyridinone (DHP), tiron (TIR)] ligands were studied at 25.0 °C and an ionic strength of 0.20 M (KCl) in aqueous solution using combined pH-potentiometric and UV-vis spectroscopic techniques. Although some interaction between the amino acids and V(III) was found, we could not obtain reliable models for these systems owing to the intensive hydrolysis of the metal ion and the formation of polynuclear hydroxo complexes. With pyridine carboxylates or [O,O] donor ligands 1:1, 1:2 (in the latter case, also 1:3 species) were found to be present as major complexes in solution. The similarities and differences in binding V(III) by these ligands are discussed.

A designed supramolecular protein assembly with in vivo enzymatic activity

Science ◽  
2014 ◽  
Vol 346 (6216) ◽  
pp. 1525-1528 ◽  
Author(s):  
Woon Ju Song ◽  
F. Akif Tezcan
Keyword(s):  
Active Site ◽  
First Principles ◽  
Self Assembly ◽  
Protein Structures ◽  
Three Dimensional ◽  
In Vivo Screening ◽  
Hydrolysis Of ◽  
Catalytic Zinc ◽  
Tetrameric Assembly

The generation of new enzymatic activities has mainly relied on repurposing the interiors of preexisting protein folds because of the challenge in designing functional, three-dimensional protein structures from first principles. Here we report an artificial metallo-β-lactamase, constructed via the self-assembly of a structurally and functionally unrelated, monomeric redox protein into a tetrameric assembly that possesses catalytic zinc sites in its interfaces. The designed metallo-β-lactamase is functional in the Escherichia coli periplasm and enables the bacteria to survive treatment with ampicillin. In vivo screening of libraries has yielded a variant that displays a catalytic proficiency [(kcat/Km)/kuncat] for ampicillin hydrolysis of 2.3 × 106 and features the emergence of a highly mobile loop near the active site, a key component of natural β-lactamases to enable substrate interactions.

scholarly journals Higher-order interfiber interactions in the self-assembly of benzene-1,3,5-tricarboxamide-based peptides in water

2021 ◽  
Author(s):  
Oleksandr Zagorodko ◽  
Tetiana Melnyk ◽  
Olivier Rogier ◽  
Vicent J. Nebot ◽  
María J. Vicent
Keyword(s):  
Aqueous Solution ◽  
Amino Acids ◽  
Self Assembly ◽  
Higher Order ◽  
The Self ◽  
Order Structures

Benzene-1,3,5-tricarboxamide-based di- and tripeptide derivatives can form various higher-order structures in aqueous solution depending on the order, hydrophobicity, and bulkiness of the amino acids in the substituent.

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