PubMed Health⌕ Search

Biomedical subjects

Marlen Schmidt

Publications and source records attributed to Marlen Schmidt.

6 recordsLinked to original sources
PubMed2007

A versatile esterase from Bacillus subtilis: cloning, expression, characterization, and its application in biocatalysis.

An esterase from Bacillus subtilis DSM402 (BS2) was cloned and functionally expressed in E. coli. The enzyme is active up to 50 degrees C, and the V(max) (1449 mM/min) and K(M) values (119 mM) were determined using p-nitrophenyl acetate as substrate. BS2 belongs to the few hydrolases that can act on tertiary alcohols and was therefore used to resolve racemic acetates of selected tertiary alcohols, but also to selectively remove the tert-butyl ester protecting group from peptides. In addition, the enzyme shows promiscuous amidase activity.

Alcohols↗
PubMed2006

Directed evolution of an esterase from Pseudomonas fluorescens yields a mutant with excellent enantioselectivity and activity for the kinetic resolution of a chiral building block.

A triple mutant of an esterase from Pseudomonas fluorescens (PFE) that was created by directed evolution exhibited high enantioselectivity (E=89) in a kinetic resolution and yielded the building block (S)-but-3-yn-2-ol. Surprisingly, a mutation close to the active site caused the formation of inclusion bodies, but remote mutations were found to be responsible for the high selectivity. Back mutations gave a variant (double mutant PFE Ile76Val/Val175Ala) that showed excellent selectivity (E=96) and activity (20 min for 50% conversion, which corresponds to 1.25 U per mg of protein).

Alkynes↗
PubMed2005

Enzymatic removal of carboxyl protecting groups. 1. Cleavage of the tert-butyl moiety.

[reaction: see text] A recent discovery that a certain amino acid motif (GGG(A)X-motif) in lipases and esterases determines their activity toward tertiary alcohols prompted us to investigate the use of these biocatalysts in the mild and selective removal of tert-butyl protecting groups in amino acid derivatives and related compounds. An esterase from Bacillus subtilis (BsubpNBE) and lipase A from Candida antarctica (CAL-A) were identified as the most active enzymes, which hydrolyzed a range of tert-butyl esters of protected amino acids (e.g., Boc-Tyr-O(t)Bu, Z-GABA-O(t)Bu, Fmoc-GABA-O(t)Bu) in good to high yields and left Boc, Z, and Fmoc-protecting groups intact.

Amino Acid Sequence↗
PubMed2005

High-throughput assays for lipases and esterases.

In the past few years a considerable number of high-throughput screening (HTS) systems have been developed, especially for lipases and esterases. In this review, a range of HTS methods for the directed evolution of these hydrolases are covered. This includes spectrophotometric and fluorimetric formats as well as other approaches to allow for fast, efficient and reliable identification of desired enzyme variants within large mutant libraries. In addition, methods for library creation and application of lipases and esterases are briefly covered.

Directed Molecular Evolution↗