Eering tuned the activity as well as the enantio- and diasteroselectivity of the reaction. Although free hemin shows strong trans selectivity, several mutant enzymes were found to be cis-selective, with up to 90 diastereoselectivity. [PubMed: 23258409] 37 . Coelho PS, Wang ZJ, Ener ME, Baril SA, Kannan A, Arnold FH, Brustad EM. A serinesubstituted P450 catalyzes highly efficient carbene transfer to olefins in vivo. Nat Chem Biol. 2013; 9(8):485?87. P450BM3 variants are shown to catalyze cyclopropanation efficiently in vivo. Mutation of the axial coordinating cysteine to serine strongly enhances this activity, leading to some of the most active and selective cyclopropanation catalysts yet reported. [PubMed: 23792734] 38? McIntosh JA, Coelho PS, Farwell CC, Wang ZJ, Lewis JC, Brown TR, Arnold FH. Enantioselective intramolecular C-H amination catalyzed by engineered cytochrome P450 enzymes in vitro and in vivo. Angew Chem Int Ed Engl. 2013; 52(35):9309?312. C-H amination is a challenging Hexanoyl-Tyr-Ile-Ahx-NH2 mechanism of action synthetic transformation with wide applicability in chemical synthesis. Here engineered P450 enzymes are shown to be highly active and enantioselective in the intramolecular formation of C-N bonds using unnatural sulfonyl azides as substrates. [PubMed: 23893546] 39. Ruppel JV, Kamble RM, Zhang XP. Cobalt-catalyzed intramolecular C-H amination with arylsulfonyl azides. Org Lett. 2007; 9(23):4889?892. [PubMed: 17935344] 40? Wang ZJ, Peck NE, Renata H, Arnold FH. Cytochrome P450 catalysed insertion of carbenoids into N-H bonds. Chem Sci. 2014 Epub ahead of print Here the scope of P450-catalyzed carbene transfer is expanded to include insertions into N-H bonds. The enzyme is selective for the singleinsertion secondary amine product, whereas hemin produces a mixture of single- and doubleinsertion products. 41. Lewis JC, Coelho PS, Arnold FH. Enzymatic functionalization of carbon-hydrogen bonds. Chem Soc Rev. 2011; 40(4):2003?021. [PubMed: 21079862] 42. Muller A, Sturmer R, Hauer B, Rosche B. Stereospecific alkyne reduction: Novel activity of old yellow enzymes. Angew Chem Int Ed Engl. 2007; 46 (18):3316?318. [PubMed: 17387664] 43. Hasnaoui-Dijoux G, Majeric Elenkov M, Lutje Spelberg JH, Hauer B, Janssen DB. Catalytic promiscuity of halohydrin Pamapimod biological activity dehalogenase and its application in enantioselective epoxide ring opening. Chem Bio Chem. 2008; 9(7):1048?051.NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author ManuscriptCurr Opin Chem Biol. Author manuscript; available in PMC 2015 April 01.McIntosh et al.Page44. Savile CK, Magloire VP, Kazlauskas RJ. Subtilisin-catalyzed resolution of N-acyl arylsulfinamides. J Am Chem Soc. 2005; 127(7):2104?113. [PubMed: 15713087] 45. Huisman GW, Collier SJ. On the development of new biocatalytic processes for practical pharmaceutical synthesis. Curr Opin Chem Biol. 2013; 17(2):284?92. [PubMed: 23462589] 46. Harris DC, Jewett MC. Cell-free biology: Exploiting the interface between synthetic biology and synthetic chemistry. Curr Opin Biotechnol. 2012; 23 (5):672?78. [PubMed: 22483202]NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author ManuscriptCurr Opin Chem Biol. Author manuscript; available in PMC 2015 April 01.McIntosh et al.PageHighlights ????Discovering enzymes for new reactions is important but challenging Cytochrome P450 enzymes catalyze many different chemical reactions in nature P450s can be engineered to catalyze reactions first discovered by synthetic chemists Engineering enhances the activity and se.Eering tuned the activity as well as the enantio- and diasteroselectivity of the reaction. Although free hemin shows strong trans selectivity, several mutant enzymes were found to be cis-selective, with up to 90 diastereoselectivity. [PubMed: 23258409] 37 . Coelho PS, Wang ZJ, Ener ME, Baril SA, Kannan A, Arnold FH, Brustad EM. A serinesubstituted P450 catalyzes highly efficient carbene transfer to olefins in vivo. Nat Chem Biol. 2013; 9(8):485?87. P450BM3 variants are shown to catalyze cyclopropanation efficiently in vivo. Mutation of the axial coordinating cysteine to serine strongly enhances this activity, leading to some of the most active and selective cyclopropanation catalysts yet reported. [PubMed: 23792734] 38? McIntosh JA, Coelho PS, Farwell CC, Wang ZJ, Lewis JC, Brown TR, Arnold FH. Enantioselective intramolecular C-H amination catalyzed by engineered cytochrome P450 enzymes in vitro and in vivo. Angew Chem Int Ed Engl. 2013; 52(35):9309?312. C-H amination is a challenging synthetic transformation with wide applicability in chemical synthesis. Here engineered P450 enzymes are shown to be highly active and enantioselective in the intramolecular formation of C-N bonds using unnatural sulfonyl azides as substrates. [PubMed: 23893546] 39. Ruppel JV, Kamble RM, Zhang XP. Cobalt-catalyzed intramolecular C-H amination with arylsulfonyl azides. Org Lett. 2007; 9(23):4889?892. [PubMed: 17935344] 40? Wang ZJ, Peck NE, Renata H, Arnold FH. Cytochrome P450 catalysed insertion of carbenoids into N-H bonds. Chem Sci. 2014 Epub ahead of print Here the scope of P450-catalyzed carbene transfer is expanded to include insertions into N-H bonds. The enzyme is selective for the singleinsertion secondary amine product, whereas hemin produces a mixture of single- and doubleinsertion products. 41. Lewis JC, Coelho PS, Arnold FH. Enzymatic functionalization of carbon-hydrogen bonds. Chem Soc Rev. 2011; 40(4):2003?021. [PubMed: 21079862] 42. Muller A, Sturmer R, Hauer B, Rosche B. Stereospecific alkyne reduction: Novel activity of old yellow enzymes. Angew Chem Int Ed Engl. 2007; 46 (18):3316?318. [PubMed: 17387664] 43. Hasnaoui-Dijoux G, Majeric Elenkov M, Lutje Spelberg JH, Hauer B, Janssen DB. Catalytic promiscuity of halohydrin dehalogenase and its application in enantioselective epoxide ring opening. Chem Bio Chem. 2008; 9(7):1048?051.NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author ManuscriptCurr Opin Chem Biol. Author manuscript; available in PMC 2015 April 01.McIntosh et al.Page44. Savile CK, Magloire VP, Kazlauskas RJ. Subtilisin-catalyzed resolution of N-acyl arylsulfinamides. J Am Chem Soc. 2005; 127(7):2104?113. [PubMed: 15713087] 45. Huisman GW, Collier SJ. On the development of new biocatalytic processes for practical pharmaceutical synthesis. Curr Opin Chem Biol. 2013; 17(2):284?92. [PubMed: 23462589] 46. Harris DC, Jewett MC. Cell-free biology: Exploiting the interface between synthetic biology and synthetic chemistry. Curr Opin Biotechnol. 2012; 23 (5):672?78. [PubMed: 22483202]NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author ManuscriptCurr Opin Chem Biol. Author manuscript; available in PMC 2015 April 01.McIntosh et al.PageHighlights ????Discovering enzymes for new reactions is important but challenging Cytochrome P450 enzymes catalyze many different chemical reactions in nature P450s can be engineered to catalyze reactions first discovered by synthetic chemists Engineering enhances the activity and se.