Recent investigations on imine reductases (IREDs) have enriched the toolbox of potential catalysts for accessing chiral amines, which are important building blocks for the pharmaceutical industry. Herein, we describe the characterization of 20 new IREDs. A C-terminal domain clustering of the bacterial protein-sequence space was performed to identify the novel IRED candidates. Each of the identified enzymes was characterized against a set of nine cyclic imine model substrates. A refined clustering towards putative active-site residues was performed and was consistent both with our screening and previously reported results. Finally, preparative scale experiments on a 100 mg scale with two purified IREDs, IR_20 from Streptomyces tsukubaensis and IR_23 from Streptomyces vidiochromogenes, were carried out to provide (R)-2-methylpiperidine in 98% ee (71% yield) and (R)-1-methyl-1,2,3,4-tetrahydroisoquinoline in >98% ee (82% yield).

A new poly(ethylene oxide)-tetraphenylalanine polymer-peptide conjugate has been prepared via a "click" reaction between an alkyne-modified peptide and an azide-terminated PEO oligomer. Self-assembled nanotubes are formed after dialysis of a THF solution of this polymer-peptide conjugate against water. The structure of these nanotubes has been probed by circular dichroism, IR, TEM, and SAXS. From these data, it is apparent that self-assembly involves the formation of antiparallel beta-sheets and pi-pi-stacking. Nanotubes are formed at concentrations between 2 and 10 mg mL(-1). Entanglement between adjacent nanotubes occurs at higher concentrations, resulting in the formation of soft hydrogels. Gel strength increases at higher polymer-peptide conjugate concentration, as expected.

A range of well-defined hydrophilic methacrylic macromonomers has been synthesized by the judicious combination of atom transfer radical polymerization (ATRP) and copper-catalyzed 1,3-dipolar cycloaddition (azide−alkyne click chemistry). An azido α-functionalized ATRP initiator was used to produce well-defined homopolymers with terminal azide functionality via ATRP in protic media at 20 °C, with generally good control being achieved over both target molecular weight and final polydispersity (M w/M n = 1.10−1.35). Suitable methacrylic monomers include 2-aminoethyl methacrylate hydrochloride, 2-(diethylamino)ethyl methacrylate, 2-(dimethylamino)ethyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-(methacryloyloxy)ethyl phosphorylcholine, glycerol monomethacrylate, potassium 3-sulfopropyl methacrylate, and quaternized 2-(dimethylamino)ethyl methacrylate. These homopolymer precursors were then efficiently clicked using either propargyl methacrylate or propargyl acrylate to yield near-monodisperse (meth)acrylate-capped macromonomers with either cationic, anionic, nonionic, or zwitterionic character. Moreover, this generic route to well-defined hydrophilic macromonomers is also suitable for “one-pot” syntheses, as exemplified for 2-hydroxyethyl methacrylate and glycerol monomethacrylate-based macromonomers.