Synthesis of the functionalizable methionine surrogate azidohomoalanine using Boc-homoserine as precursor.

This protocol describes a synthetic route to the non-canonical amino acid azidohomoalanine (AHA) using protected homoserine as a starting material. An alternative route to AHA is presented in a companion paper. This synthesis can be completed in 5 days.

Preparation of the functionalizable methionine surrogate azidohomoalanine via copper-catalyzed diazo transfer.

The azide functional group has assumed a prominent role in chemical biology efforts in recent years. Azides may be readily introduced into proteins upon replacement of methionine residues with the non-canonical amino acid azidohomoalanine (AHA). This protocol describes a synthetic route to AHA based on the copper-catalyzed conversion of amines to azides.

Nitrile hydrolysis activity of Rhodococcus erythropolis NCIMB 11540 whole cells.

The nitrile hydrolyzing properties of the bacterium strain Rhodococcus erythropolis NCIMB 11540 have been investigated. Using whole cells of the microorganism, a wide variety of aromatic and aliphatic cyanide-containing substrates was successfully hydrolyzed to the corresponding amide or acid. In the case of dicyanides, selective monohydrolysis took place, which was further explored in the desymmetrization of malononitriles resulting in the corresponding cyano amides in enantiomeric excesses of up to 98%.

Discovery of aminoacyl-tRNA synthetase activity through cell-surface display of noncanonical amino acids.

The incorporation of noncanonical amino acids into recombinant proteins in Escherichia coli can be facilitated by the introduction of new aminoacyl-tRNA synthetase activity into the expression host. We describe here a screening procedure for the identification of new aminoacyl-tRNA synthetase activity based on the cell surface display of noncanonical amino acids. Screening of a saturation mutagenesis library of the E.

Presentation and detection of azide functionality in bacterial cell surface proteins.

An improved protocol for copper-catalyzed triazole formation on the bacterial cell surface is described. Addition of highly pure CuBr to cells treated with azidohomoalanine (2) leads to ca. 10-fold more extensive cell surface labeling than previously observed.

A stereodivergent approach to substituted 4-hydroxypiperidines.

A stereodivergent route toward both diastereomeric forms of functionalized 4-hydroxypiperidines has been successfully developed. This route involves biocatalytic generation of the enantiopure starting materials followed by functionalization via N-acyliminium ion-mediated CC-bond formation.