Laboratory-Scale Hydroxylation of Steroids by P450BM3 Variants.

This chapter describes the asymmetric hydroxylation of steroids on laboratory preparative scale, using engineered variants of P450BM3 (CYP102A1) as enzyme catalyst. The following protocol covers the creation of an Escherichia coli BL21-Gold (DE3) expression strain, including necessary control experiments like plasmid preparation, test expression, and creation of storage cultures, to verify successful experimental access to recombinant expressed P450BM3 variants. The recombinant expressed P450BM3 variants are obtained as cleared cell lysate and used in a biotransformation setup to hydroxylate 2.8 mg and up to 15 mg testosterone in the presented protocol. Since P450BM3 depends on NADPH as an electron source for the reaction, a glucose and glucose dehydrogenate based recycling system is added to the reaction. The protocol further includes liquid-liquid extraction of hydroxytestosterone and directs the experimenter to compound purification via column chromatography.

Revealing Additional Stereocomplementary Pairs of Old Yellow Enzymes by Rational Transfer of Engineered Residues.

Every year numerous protein engineering and directed evolution studies are published, increasing the knowledge that could be used by protein engineers. Here we test a protein engineering strategy that allows quick access to improved biocatalysts with very little screening effort. Conceptually it is assumed that engineered residues previously identified by rational and random methods induce similar improvements when transferred to family members. In an application to ene-reductases from the Old Yellow Enzyme (OYE) family, the newly created variants were tested with three compounds, revealing more stereocomplementary OYE pairs with potent turnover frequencies (up to 660 h-1 ) and excellent stereoselectivities (up to >99 %). Although systematic prediction of absolute enantioselectivity of OYE variants remains a challenge, "scaffold sampling" was confirmed as a promising addition to protein engineers' collection of strategies.

Bioorthogonal Enzymatic Activation of Caged Compounds.

Engineered cytochrome P450 monooxygenase variants are reported as highly active and selective catalysts for the bioorthogonal uncaging of propargylic and benzylic ether protected substrates, including uncaging in living E. coli. observed selectivity is supported by induced-fit docking and molecular dynamics simulations. This proof-of-principle study points towards the utility of bioorthogonal enzyme/protecting group pairs for applications in the life sciences.