A small molecule enhances arrestin-3 binding to the β-adrenergic receptor.

G protein-coupled receptor (GPCR) signaling is terminated by arrestin binding to a phosphorylated receptor. Binding propensity has been shown to be modulated by stabilizing the pre-activated state of arrestin through point mutations or C-tail truncation. Here, we hypothesize that pre-activated rotated states can be stabilized by small molecules, and this can promote binding to phosphorylation-deficient receptors, which underly a variety of human disorders.

Functional Characterization and Synthetic Application of Is2-SDR, a Novel Thermostable and Promiscuous Ketoreductase from a Hot Spring Metagenome.

In a metagenome mining-based search of novel thermostable hydroxysteroid dehydrogenases (HSDHs), enzymes that are able to selectively oxidize/reduce steroidal compounds, a novel short-chain dehydrogenase/reductase (SDR), named Is2-SDR, was recently discovered. This enzyme, found in an Icelandic hot spring metagenome, shared a high sequence similarity with HSDHs, but, unexpectedly, showed no activity in the oxidation of the tested steroid substrates, e.g.

Selective Supercritical CO Extraction and Biocatalytic Valorization of L. Industrial Residuals.

The valorization of biomass residuals constitutes a key aspect of circular economy and thus a major challenge for the scientific community. Among industrial wastes, plant residuals could represent an attractive source of bioactive compounds. In this context, a residue from the industrial extraction of L.

Stereoselective Biocatalyzed Reductions of Ginger Active Components Recovered from Industrial Wastes.

Ginger is among the most widespread and widely consumed traditional medicinal plants around the world. Its beneficial effects, which comprise e. g.

Studies on the Catalytic Promiscuity of Limonene Epoxide Hydrolases in the Non-hydrolytic Ring Opening of 1,2-Epoxides.

The non-hydrolytic ring opening of 1,2-epoxides in the presence of limonene epoxide hydrolases (LEHs) and different nucleophiles has been investigated. Lyophilized, wild-type LEHs were tested in selected water-saturated organic solvents in the presence of cyclohexene oxide as substrate and different alcohols, thiols and primary amines as nucleophiles. Although the LEHs retained an appreciable catalytic activity under different reaction conditions, formation of the desired 1,2-substituted cyclohexanols was not observed.

Stereoselectivity Switch in the Reduction of α-Alkyl-β-Arylenones by Structure-Guided Designed Variants of the Ene Reductase OYE1.

Ene reductases from the Old Yellow Enzyme (OYE) family are industrially interesting enzymes for the biocatalytic asymmetric reduction of alkenes. To access both enantiomers of the target reduced products, stereocomplementary pairs of OYE enzymes are necessary, but their natural occurrence is quite limited. A library of wild type ene reductases from different sources was screened in the stereoselective reduction of a set of representative α-alkyl-β-arylenones to investigate the naturally available biodiversity.

New Thermophilic α/β Class Epoxide Hydrolases Found in Metagenomes From Hot Environments.

Two novel epoxide hydrolases (EHs), Sibe-EH and CH65-EH, were identified in the metagenomes of samples collected in hot springs in Russia and China, respectively. The two α/β hydrolase superfamily fold enzymes were cloned, over-expressed in , purified and characterized. The new EHs were active toward a broad range of substrates, and in particular, Sibe-EH was excellent in the desymmetrization of -2,3-epoxybutane producing the (2,3)-diol product with exceeding 99%.

Novel thermostable amine transferases from hot spring metagenomes.

Hot spring metagenomes, prepared from samples collected at temperatures ranging from 55 to 95 °C, were submitted to an in silico screening aimed at the identification of novel amine transaminases (ATAs), valuable biocatalysts for the preparation of optically pure amines. Three novel (S)-selective ATAs, namely Is3-TA, It6-TA, and B3-TA, were discovered in the metagenome of samples collected from hot springs in Iceland and in Italy, cloned from the corresponding metagenomic DNAs and overexpressed in recombinant form in E. coli.

Structural and biochemical insights into 7β-hydroxysteroid dehydrogenase stereoselectivity.

Hydroxysteroid dehydrogenases are of great interest as biocatalysts for transformations involving steroid substrates. They feature a high degree of stereo- and regio-selectivity, acting on a defined atom with a specific configuration of the steroid nucleus. The crystal structure of 7β-hydroxysteroid dehydrogenase from Collinsella aerofaciens reveals a loop gating active-site accessibility, the bases of the specificity for NADP(+) , and the general architecture of the steroid binding site.

Discovery and characterization of thermophilic limonene-1,2-epoxide hydrolases from hot spring metagenomic libraries.

The epoxide hydrolases (EHs) represent an attractive option for the synthesis of chiral epoxides and 1,2-diols which are valuable building blocks for the synthesis of several pharmaceutical compounds. A metagenomic approach has been used to identify two new members of the atypical EH limonene-1,2-epoxide hydrolase (LEH) family of enzymes. These two LEHs (Tomsk-LEH and CH55-LEH) show EH activities towards different epoxide substrates, differing in most cases from those previously identified for Rhodococcus erythropolis (Re-LEH) in terms of stereoselectivity.

Substrate scope and synthetic applications of the enantioselective reduction of α-alkyl-β-arylenones mediated by Old Yellow Enzymes.

The ene-reductases mediated bioreduction of a selection of open-chain α-alkyl-β-aryl enones afforded the corresponding saturated α-chiral ketones in high yield and optical purity in several cases. The stereo-electronic requirements of the reaction have been investigated, considering the nature and location of substituents on the aromatic ring as well as the steric hindrance at the α-position and adjacent to the carbonyl functionality. The general considerations drawn allow us to guide the design of α,β-unsaturated ketones to be employed as substrates of ene-reductases in future preparative applications.

In search of sustainable chemical processes: cloning, recombinant expression, and functional characterization of the 7α- and 7β-hydroxysteroid dehydrogenases from Clostridium absonum.

Nicotinamide adenine dinucleotide phosphate-dependent 7α-hydroxysteroid dehydrogenase (7α-HSDH) and 7β-hydroxysteroid dehydrogenases (7β-HSDH) from Clostridium absonum catalyze the epimerization of primary bile acids through 7-keto bile acid intermediates and may be suitable as biocatalysts for the synthesis of bile acids derivatives of pharmacological interest. C. absonum 7α-HSDH has been purified to homogeneity and the N-terminal sequence has been determined by Edman sequencing.

Purification and characterization of the enantioselective esterase from Kluyveromyces marxianus CBS 1553.

An intracellular esterase from the yeast Kluyveromyces marxianus CBS 1553 with interesting enantioselective hydrolytic activity towards racemic esters of 1,2-O-isopropylidene glycerol (IPG) was purified and characterized. Optimal culture conditions for the obtainment of the enantioselective esterase on a 5 l-fermentation scale were investigated. Two esterase activities (EST1 and EST2) in the crude cell extract were identified by native PAGE with specific activity staining and separated from each other by anion-exchange chromatography.