Conformations of Macrocyclic Peptides Sampled by Nuclear Magnetic Resonance: Models for Cell-Permeability.

The biological activities and pharmacological properties of peptides and peptide mimetics are determined by their conformational states. Therefore, a detailed understanding of the conformational landscape is crucial for rational drug design. Nuclear magnetic resonance (NMR) is the only method for structure determination in solution.

Promiscuity of Omphalotin A Biosynthetic Enzymes Allows de novo Production of Non-Natural Multiply Backbone N-Methylated Peptide Macrocycles in Yeast.

Multiple backbone N-methylation and macrocyclization improve the proteolytic stability and oral availability of therapeutic peptides. Chemical synthesis of such peptides is challenging, in particular for the generation of peptide libraries for screening purposes. Enzymatic backbone N-methylation and macrocyclization occur as part of both non-ribosomal and ribosomal peptide biosynthesis, exemplified by the fungal natural products cyclosporin A and omphalotin A, respectively.

Enzyme-mediated backbone N-methylation in ribosomally encoded peptides.

Backbone N-methylation as a posttranslational modification was recently discovered in a class of ribosomally encoded peptides referred to as borosins. The founding members of the borosins are the omphalotins (A-I), backbone N-methylated, macrocyclic dodecapeptides produced by the mushroom Omphalotus olearius. Omphalotins display a strong and selective toxicity toward the plant parasitic nematode Meloidogyne incognita.

Identification, heterologous production and bioactivity of lentinulin A and dendrothelin A, two natural variants of backbone N-methylated peptide macrocycle omphalotin A.

Backbone N-methylation and macrocyclization improve the pharmacological properties of peptides by enhancing their proteolytic stability, membrane permeability and target selectivity. Borosins are backbone N-methylated peptide macrocycles derived from a precursor protein which contains a peptide α-N-methyltransferase domain autocatalytically modifying the core peptide located at its C-terminus. Founding members of borosins are the omphalotins from the mushroom Omphalotus olearius (omphalotins A-I) with nine out of 12 L-amino acids being backbone N-methylated.

Selecting cells expressing high levels of recombinant proteins using the GPI-anchored protein with selenocysteine system.

Most biopharmaceutical proteins are produced in mammalian cells because they have the advantageous capacity for protein folding, assembly, and posttranslational modifications. To satisfy the increasing demand for these proteins for clinical purposes and studies, traditional methods to improve protein productivity have included gene amplification, host cell engineering, medium optimization, and screening methods. However, screening and selection of high-producing cell lines remain complex and time consuming.

Substrate Plasticity of a Fungal Peptide α--Methyltransferase.

The methylation of amide nitrogen atoms can improve the stability, oral availability, and cell permeability of peptide therapeutics. Chemical -methylation of peptides is challenging. Omphalotin A is a ribosomally synthesized, macrocylic dodecapeptide with nine backbone -methylations.

The current strategies and parameters for the enhanced microbial production of 2,3-butanediol.

2,3-Butanediol (2,3-BD) is a propitious compound with many industrial uses ranging from rubber, fuels, and cosmetics to food additives. Its microbial production has especially attracted as an alternative way to the petroleum-based production. However, 2,3-BD production has always been hampered by low yields and high production costs.

Current Immunoassay Methods for the Rapid Detection of Aflatoxin in Milk and Dairy Products.

The presence of mycotoxins in foodstuff causes serious health problems to consumers and economically affects the food industry. Among the mycotoxins, aflatoxins are very toxic and highly carcinogenic contaminants which affect the safety of many foods, and therefore endanger human health. Aflatoxin M (AFM ) found in milk results from the biotransformation of aflatoxin B .

Molecular switching system using glycosylphosphatidylinositol to select cells highly expressing recombinant proteins.

Although many pharmaceutical proteins are produced in mammalian cells, there remains a challenge to select cell lines that express recombinant proteins with high productivity. Since most biopharmaceutical proteins are secreted by cells into the medium, it is difficult to select cell lines that produce large amounts of the target protein. To address this issue, a new protein expression system using the glycosylphosphatidylinositol (GPI)-anchor was developed.