α-Chymotrypsin-Induced Acetalization of Aldehydes and Ketones with Alcohols

There is emerging evidence that biocompatible zwitterionic materials can prevent nonspecific interactions within protein systems and increase protein stability. Here, a zwitterionic microgel was synthesized from poly (carboxybetaine methyl methacrylate) (pCB) using an inverse emulsion, free radical polymerization reaction technique. The microgel was loaded with a model enzyme, α‐chymotrypsin (ChT), using a post‐fabrication loading technique. A reaction scheme was developed and studied for covalent immobilization of ChT within the microgel. Confocal laser microscopy studies showed that immobilized ChT (i‐ChT) was distributed within the hydrogel. The enzyme‐immobilized microgels showed excellent reusability (72% of its initial activity after 10 uses) and could undergo several freezing/drying/rehydration cycles while retaining enzymatic activity. The i‐ChT activity, half‐life, and conformational stability were studied at varying pH and temperatures with results compared to free ChT in buffer. ChT immobilized within pCB hydrogel showed increased enzymatic stability as observed by a 13°C increase in the temperature at which i‐ChT loses activity compared to free ChT. Furthermore, enzyme half‐life increased up to seven‐fold for the pCB immobilized ChT, and the increased stability resulted in higher activity at elevated pH. The i‐ChT was most active at pH of 8.5 and was partially active up to the pH of 10.2.

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Zwitterionic poly(carboxybetaine) microgels for enzyme (chymotrypsin) covalent immobilization with extended stability and activity

Erfani

Zarrintaj

Seaberg

et al. 2021

J of Applied Polymer Sci

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Homologation of Alkyl Acetates, Alkyl Ethers, Acetals, and Ketals by Formal Insertion of Diazo Compounds into a Carbon–Carbon Bond

Wang

Nishimoto

et al. 2021

Synthesis

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We have accomplished homologation of alkyl acetates, alkyl ethers, acetals, and ketals via formal insertion of diazo esters into carbon-carbon σ-bonds. The combined Lewis acid of InI3 with Me3SiBr catalyzed the homologation of alkyl acetates and alkyl ethers. That of acetals and ketals was catalyzed solely by the use of InBr3. The key point of the homologation mechanism is that the indium-based Lewis acids have the appropriate amount of Lewis acidity to achieve both the abstraction and release of leaving groups. The abstraction of a leaving group by an indium-based Lewis acid, the electrophilic addition of carbocation or oxonium intermediates to diazo esters followed by the rearrangement of carbon substituents provides the corresponding cation intermediates. Finally, the leaving group that is captured by the Lewis acid bonds with cation intermediates to furnish the homologated products.

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α-Chymotrypsin-Induced Acetalization of Aldehydes and Ketones with Alcohols

Cited by 2 publications

References 39 publications

Zwitterionic poly(carboxybetaine) microgels for enzyme (chymotrypsin) covalent immobilization with extended stability and activity

Zwitterionic poly(carboxybetaine) microgels for enzyme (chymotrypsin) covalent immobilization with extended stability and activity

Homologation of Alkyl Acetates, Alkyl Ethers, Acetals, and Ketals by Formal Insertion of Diazo Compounds into a Carbon–Carbon Bond

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