Green Oxidation of Amines by a Novel Cold-Adapted Monoamine Oxidase MAO P3 from Psychrophilic Fungi Pseudogymnoascus sp. P3

The use of monoamine oxidases (MAOs) in amine oxidation is a great example of how biocatalysis can be applied in the agricultural or pharmaceutical industry and manufacturing of fine chemicals to make a shift from traditional chemical synthesis towards more sustainable green chemistry. This article reports the screening of fourteen Antarctic fungi strains for MAO activity and the discovery of a novel psychrozyme MAOP3 isolated from the Pseudogymnoascus sp. P3. The activity of the native enzyme was 1350 ± 10.5 U/L towards a primary (n-butylamine) amine, and 1470 ± 10.6 U/L towards a secondary (6,6-dimethyl-3-azabicyclohexane) amine. MAO P3 has the potential for applications in biotransformations due to its wide substrate specificity (aliphatic and cyclic amines, pyrrolidine derivatives). The psychrozyme operates at an optimal temperature of 30 °C, retains 75% of activity at 20 °C, and is rather thermolabile, which is beneficial for a reduction in the overall costs of a bioprocess and offers a convenient way of heat inactivation. The reported biocatalyst is the first psychrophilic MAO; its unique biochemical properties, substrate specificity, and effectiveness predispose MAO P3 for use in environmentally friendly, low-emission biotransformations.

Analysis of Sequence Divergence in Mammalian ABCGs Predicts a Structural Network of Residues That Underlies Functional Divergence

The five members of the mammalian G subfamily of ATP-binding cassette transporters differ greatly in their substrate specificity. Four members of the subfamily are important in lipid transport and the wide substrate specificity of one of the members, ABCG2, is of significance due to its role in multidrug resistance. To explore the origin of substrate selectivity in members 1, 2, 4, 5 and 8 of this subfamily, we have analysed the differences in conservation between members in a multiple sequence alignment of ABCG sequences from mammals. Mapping sets of residues with similar patterns of conservation onto the resolved 3D structure of ABCG2 reveals possible explanations for differences in function, via a connected network of residues from the cytoplasmic to transmembrane domains. In ABCG2, this network of residues may confer extra conformational flexibility, enabling it to transport a wider array of substrates.

Reshaping the Active Pocket of Esterase Est816 for Resolution of Economically Important Racemates

One of the most important industrial applications of bacterial esterases is the production of optically pure compounds. However, the contradiction between the wide substrate specificity and high enantioselectivity of natural...

Covalent Immobilization of Thiol Proteinases on Chitosan

Plant enzymes such as ficin (EC 3.4.22.3), papain (EC 3.4.22.2) and bromelain (EC 3.4.22.4) are obtained from tropical plants. These biocatalysts belong to thiol proteases, in the active center of which cysteine is contained. Ficin, papain and bromelain have a wide substrate specificity, which provides a demand for their use in various industries. Enzymes in the free state are less commonly used; immobilized biocatalysts are the preferred form. The aim of this work was to determine the optimal concentration of a crosslinking agent in the covalent immobilization of ficin, papain and bromelain on a chitosan matrix. Ficin, papain and bromelain (Sigma) were chosen as objects of study. An acid-soluble chitosan (350 kDa, Bioprogress CJSC) was used as an immobilization carrier. The concentration range of glutaraldehyde (crosslinking agent) ranged from 1 to 25%. Suitable concentrations of glutaraldehyde for covalent immobilization were identified by the optimal ratio of protein content (mg per g of carrier), total activity (in units per ml of solution) and specific activity (in units per mg of protein). It was shown that for covalent immobilization of ficin and bromelain on a chitosan matrix, it is most promising to use 10% glutaraldehyde. For immobilization of papain on chitosan by covalent means, the concentration of glutaraldehyde equal to 20% is optimal.

Sir Howard Dalton. 8 February 1944 — 12 January 2008

Howard Dalton was an outstanding microbiologist who, after his remarkably productive DPhil work in the Nitrogen Fixation Laboratory at the University of Sussex, and a short period in the USA, spent his research career at the University of Warwick. He devoted himself to the elucidation of the process of methane oxidation by bacteria that use this relatively inert gas as their sole source of carbon and energy. He discovered two completely novel multicomponent monooxygenase enzymes responsible for the initial oxidation of methane to methanol. He then continued to elucidate their functions, mechanisms, regulation and structures. Their wide substrate specificity led to his interest in using these and related enzymes for biocatalysis, biological transformations and bioremediation. While remaining at Warwick University he also acted as a highly appreciated Chief Scientific Advisor to the UK Government at the Department for the Environment and Rural Affairs (Defra). Howard was a highly effective scientist, a down-to-earth, self-effacing man, outgoing and witty, an inspirational colleague who above all else made science fun.