Enzymatic hydrolysis of β-lactam antibiotics at low pH in a two-phase "aqueous solution - water-immiscible 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 waterbutylacetate system at pH 34 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 7.58.0 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.

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Enzymatic hydrolysis of starch in water-immiscible organic solvent, two-phase systems

Applied Biochemistry and Biotechnology ◽

10.1007/bf02783550 ◽

1995 ◽

Vol 55 (2) ◽

pp. 75-86 ◽

Cited By ~ 6

Author(s):

Takashi Morita ◽

Isao Karube

Keyword(s):

Enzymatic Hydrolysis ◽

Organic Solvent ◽

Two Phase ◽

Phase Systems ◽

Hydrolysis Of

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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 ◽

10.3390/mi10070452 ◽

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.

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Liquid-phase hydrodechlorination of chlorobenzene by molecular hydrogen: The influence of reaction medium on process efficiency

Pure and Applied Chemistry ◽

10.1351/pac-con-08-10-12 ◽

2009 ◽

Vol 81 (11) ◽

pp. 2107-2114 ◽

Cited By ~ 4

Author(s):

Valentina I. Simagina ◽

Elena S. Tayban ◽

Ekaterina D. Grayfer ◽

Anna G. Gentsler ◽

Oksana V. Komova ◽

...

Keyword(s):

Organic Solvent ◽

Catalyst Deactivation ◽

Catalyst Activity ◽

Secondary Alcohol ◽

Reaction Medium ◽

Solvent System ◽

Chloride Ions ◽

Process Efficiency ◽

Two Phase ◽

Organic Solvent System

Catalytic hydrodechlorination (HDCl) of chlorobenzene was carried out in a two-phase aqueous–organic solvent system and a single-phase solvent composed of saturated KOH solution in a secondary alcohol over Pd-based catalysts at 50 °C and atmospheric pressure of H2. It was shown that an aqueous–organic solvent system containing propan-2-ol and aqueous KOH increases catalyst activity by promoting mass transfer of the formed chloride ions to water phase that prevents catalyst deactivation. It is inferred that propan-2-ol favors hydrogen activation during the HDCl process. Use of the Pd catalysts based on hydrophobic carbon support enables chlorobenzene HDCl to proceed in a two-phase solvent at a satisfactory rate, even in the absence of phase-transfer catalysts.

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Generation of highly amenable cellulose-Iβ via selective delignification of rice straw using a reusable cyclic ether-assisted deep eutectic solvent system

Scientific Reports ◽

10.1038/s41598-020-80719-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Chiranjeevi Thulluri ◽

Ravi Balasubramaniam ◽

Harshad Ravindra Velankar

Keyword(s):

Enzymatic Hydrolysis ◽

Rice Straw ◽

Deep Eutectic Solvent ◽

Solvent System ◽

Cyclic Ether ◽

Cellulolytic Enzymes ◽

Ammonium Bromide ◽

Selective Delignification ◽

Cellulose Iβ ◽

Hydrolysis Of

AbstractCellulolytic enzymes can readily access the cellulosic component of lignocellulosic biomass after the removal of lignin during biomass pretreatment. The enzymatic hydrolysis of cellulose is necessary for generating monomeric sugars, which are then fermented into ethanol. In our study, a combination of a deep eutectic (DE) mixture (of 2-aminoethanol and tetra-n-butyl ammonium bromide) and a cyclic ether (tetrahydrofuran) was used for selective delignification of rice straw (RS) under mild conditions (100 °C). Pretreatment with DE-THF solvent system caused ~ 46% delignification whereas cellulose (~ 91%) and hemicellulose (~ 67%) recoveries remained higher. The new solvent system could be reused upto 10 subsequent cycles with the same effectivity. Interestingly, the DE-THF pretreated cellulose showed remarkable enzymatic hydrolysability, despite an increase in its crystallinity to 72.3%. Contrary to conventional pretreatments, we report for the first time that the enzymatic hydrolysis of pretreated cellulose is enhanced by the removal of lignin during DE-THF pretreatment, notwithstanding an increase in its crystallinity. The current study paves way for the development of newer strategies for biomass depolymerization with DES based solvents.

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Tape Casting of Silicon Nitride

MRS Proceedings ◽

10.1557/proc-287-265 ◽

1992 ◽

Vol 287 ◽

Cited By ~ 2

Author(s):

Young-Wook Kim ◽

June-Gunn Lee

Keyword(s):

Silicon Nitride ◽

Organic Solvent ◽

Rheological Properties ◽

Tape Casting ◽

Solvent System ◽

Nitride Powder ◽

Closed Porosity ◽

Silicon Nitride Powder ◽

Polymeric Dispersant ◽

Organic Solvent System

ABSTRACTTape casting behavior of submicron silicon nitride powder(UBE SN–E1O) with Al2O3 and Y2O3 as sintering additives was studied. It was found that Hypermer KD1(polymeric dispersant) is effective dispersant for submicron silicon nitride in organic solvent system.Optimization of the rheological properties of the slurries allows the homogeneous green tapes with green densities of 45–50% theoretical. The cast tapes could be sintered to closed porosity with densities of higher than 96% theoretical.

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