Hot or not? Discovery and characterization of a thermostable alditol oxidase from Acidothermus cellulolyticus 11B

We describe the discovery, isolation and characterization of a highly thermostable alditol oxidase from Acidothermus cellulolyticus 11B. This protein was identified by searching the genomes of known thermophiles for enzymes homologous to Streptomyces coelicolor A3(2) alditol oxidase (AldO). A gene (sharing 48% protein sequence identity to AldO) was identified, cloned and expressed in Escherichia coli. Following 6xHis tag purification, characterization revealed the protein to be a covalent flavoprotein of 47 kDa with a remarkably similar reactivity and substrate specificity to that of AldO. A steady-state kinetic analysis with a number of different polyol substrates revealed lower catalytic rates but slightly altered substrate specificity when compared to AldO. Thermostability measurements revealed that the novel AldO is a highly thermostable enzyme with an unfolding temperature of 84 °C and an activity half-life at 75 °C of 112 min, prompting the name HotAldO. Inspired by earlier studies, we attempted a straightforward, exploratory approach to improve the thermostability of AldO by replacing residues with high B-factors with corresponding residues from HotAldO. None of these mutations resulted in a more thermostable oxidase; a fact that was corroborated by in silico analysis

Polyaniline supported cobalt(II) salen catalysed synthesis of pyrrolidine containing α-hydroxyamide core structures as inhibitors for HIV proteases

A novel synthesis of pyrrolidine containing α-hydroxyamide core structures as inhibitors for HIV protease is developed by employing polyaniline supported cobalt (II) salen catalysed formation of the epoxide from cinnamoylamides of L-proline followed by its opening with anilines at ambient condition

Cobalt catalysed allylic and benzylic oxidations with dioxygen in the presence of ethyl 2-oxocyclopentanecarboxylate

An efficient allylic and benzylic oxidation of various cyclic alkenes and benzylic compounds respectively can be achieved with dioxygen in the presence of ethyl 2-oxocyclopentanecarboxylate 2 and catalytic amount of cobalt(II) Schiff's base complex 1

Novel vanadium-catalyzed oxidation of alcohols to aldehydes and ketones under atmospheric oxygen

Oxidation of alcohols to aldehydes and ketones has been studied in high yields using atmospheric oxygen and a catalytic amount of V2O5 in toluene under heating (ca. 100 °C). Secondary alcohols can be chemoselectively converted into ketones in the presence of primary hydroxy groups

Cobalt(II)-catalyzed chemoselective synthesis of acetals from aldehydes

The acetalization of aldehydes has been studied with methanol, ethanol, and 2-propanol using CoCl<SUB>2</SUB> in high yields under reflux conditions. The reaction is simple, efficient, chemoselective and does not involve any other additive

Cobalt(II)-catalyzed oxidation of alcohols into carboxylic acids and ketones with hydrogen peroxide

The oxidation of aliphatic and aromatic alcohols into the corresponding carboxylic acid analogues and ketones has been carried out using 30% H2O2 and cobalt(II) complex 1 in good to high yields. The reaction is safe, clean and functions in the absence of additives

Asymmetric desymmetrization of meso-pyrrolidine derivatives by enantiotopic selective C−H hydroxylation using (salen)manganese(III) complexes

Chiral (salen)manganese(III) complexes 1 catalyzed the asymmetric desymmetrization of N-protectedmeso-pyrrolidine derivatives 3, 6–8, 15 and 18 by enantiotopic selective C-H oxidation in the presence of terminal oxidant iodosylbenzene. The oxidation occurred chemoselectively at the carbon α to the nitrogen atom to afford optically active hydroxypyrrolidine derivatives 9, 11, 13, 16, 19 and 21 that were further oxidized to chiral lactams with Jones reagent. The N-protecting groups of the meso-pyrrolidine derivatives have notable effect on the enantioselectivity