Mark Ruszczycky Degree: B.S., University of California, RiversideM.S., University of California, RiversideM.D./Ph.D. Case Westrern Reserve Entered Group: Summer, 2008 Research Projects: Mechanistic Studies of Novel Enzyme Catalysis Group Publications: Szu, P.; Ruszczucky, M.; Choi, S. H.; Yan, F.; Liu, H.-w. “Characterization and Mechanistic Studies of DesII: A Radical S-Adenosylmethionine Enzyme Involved in the Biosynthesis of TDP-D-Desosamine.” J. Am. Chem. Soc. 2009, 131, 14030-14042. Ruszczycky, M. W.; Choi, S. H.; Liu, H.-w. “Stoichiometry of the Redox Neutral Deamination and Oxidative Dehydrogenation Reactions Catalyzed by the Radical SAM Enzyme DesII.” J. Am. Chem. Soc.2010, 132, 2359-2369. Kim, H. J.; Ruszczycky, M. W.; Choi, S. H.; Liu, Y.-n.; Liu, H.-w. “An Enzyme-Catalyzed [4+2] Cycloaddition is a Key Step in the Biosynthesis of Spinosyn A.” Nature 2011, 473, 109-112. Ruszcycky, M. W.; Choi, S.-h.; Mansoorabadi, S. O.; Liu, H.-w. “Mechanistic Studies of the Radical SAM Enzyme DesII: EPR Characterization of a Radical Intermediate Generated During Its Catalyzed Dehydrogenation of TDP-D-Quinovose.” J. Am. Chem. Soc. 2011, 133, 7292-7295. Choi, S.-h.; Ruszcycky, M. W.; Zhang, H.; Liu, H.-w. “A Fluoro Analogue of UDP-α-D-Glucuronic Acid is an Inhibitor of UDP-α-D-Apiose/UDP-α-D-Xylose Synthase.” Chem. Comm. 2011, 10130-10132. Sun, H. G.; Ruszczycky, M. W.; Chang, W.-c.; Thibodeaux, C. J.; Liu, H.-w. “Nucleophilic Participation of the Reduced Flavin Cofactor in the Mechanism of UDP-Galactopyranose Mutase.” J. Biol. Chem. 2012,287, 4602-4608. Ruszczycky, M. W.; Ogasawara, Y.; Liu, H.-w. “Radical SAM Enzymes in the Biosynthesis of Sugar-Containing Natural Products.” Biochem. Biophys. Acta Proteins & Proteomics, 2012, 1824, 1231-1244. Kim, H. J.; Ruszczycky, M. W.; Liu, H.-w. “Current Development and Challenges in the Search of a Naturally Selected Diels-Alderase.” Cur. Opin. Chem. Biol. 2012, 16, 124-131. Ruszczycky, M. W.; Choi, S. H.; Liu, H.-w. “A Combined EPR-Kinetic Isotope Effect Study of Radical-Mediated Dehydrogenation of an Alcohol by the Radical SAM Enzyme DesII: Evidence for General Base Catalysis. ” Proc. Natl. Acad. Sci. USA 2013, 110, 2088-2093 Ko, Y.; Ruszczycky, M. W.; Liu, H.-w. “Mechanistic Studies of the Radical SAM Enzyme DesII with TDP-D-fucose.” Angew. Chem. Int. Ed. 2015, 54, 860-863. Ruszczycky, M. W.; Liu, H.-w. “Mechanistic Enzymology of the Radical SAM Enzyme DesII.” Israel. J. Chem. 2015, 55, 315-324. Lin, G.-M.; Choi, S.-h.; Ruszczycky, M. W.; Liu, H.-w. “Mechanistic Investigation of the Radical S-Adenosyl-methionine Enzyme DesII Using Fluorinated Analogs.” J. Am. Chem. Soc. 2015, 137, 4964-4967. Liu, C.-H.; Wang, S.-A.; Ruszczycky, M. W.; Chen, H.; Li, K.; Murakami, K.; Liu, H.-w. “Studies of 1-Amino-2,2-difluorocyclopropane-1-carboxylate: Mechanism of Decomposition and Inhibition of ACC Deaminase.” Org. Lett. 2015, 17, 3342-3345. Jeon, B.-s.; Wang, S.-A.; Ruszczycky, M. W.; Liu, H.-w. “Natural [4+2]-Cyclases.” Chem. Review. 2017, 117, 5367-5388. Ko, Y.; Wang, S.-A.; Ogasawara, Y.; Ruszczycky, M. W.; Liu, H.-w. “Characterization of Enzyme-catalyzed Pyrazolopyrimidine Formation in the Biosynthesis of Formycin A.” Org. Lett. 2017, 19, 1426-1429. Jeon, B.-s.; Ruszczycky, M. W.; Russell, W. K.; Lin, G.-M.; Kim, N.; Choi, S.-h.; Wang, S-A.; Liu, Y.-n.; Patrick, J.; Russell, D. H.; Liu, H.-w. “Mechanistic Studies of the SpnF-Catalyzed [4+2]-Cycloaddition in the Biosynthesis of Spinosyn A.” Proc. Natl. Acad. Sci. USA 2017, 114, 10408-10413. Ruszczycky, M. W.; Liu, H.-w. “Theory and Application of the Relationship between Steady-State Isotope Effects on Enzyme Intermediate Concentrations and Net Rate Constants.” Meth. Enzymol. 2017, 596, 459-499. Ruszczycky, M. W.; Liu, H.-w. “The Surprising History of an Antioxidant.” Nature 2017, 551, 37-38. Ko, Y.; Lin, G.-M.; Ruszczycky, M. W.; Liu, H.-w. “Mechanistic Implications of the Deamination of TDP-4-amino-4-deoxy-fucose Catalyzed by the Radical SAM Enzyme DesII.” Biochemistry 2018, 57, 3130-3133. Ruszczycky, M. W.; Zhong, A.; Liu, H.-w. “Following the Electrons: Peculiarities in the Catalytic Cycles of Radical SAM Enzymes.” Nat. Prod. Rep. 2018, 35, 615-621. Ushimaru, R.; Ruszczycky, M. W.; Chang, W.-C.; Yan, F.; Liu, Y.-n.; Liu, H.-w. “Substrate Conformation Correlates with the Outcome of Hyoscyamine 6β-Hydroxylase Catalyzed Oxidation Reactions.” J. Am. Chem. Soc. 2018, 140, 7433-7436. Ushimaru, R.; Ruszczycky, M. W.; Liu, H.-w. “Changes in Regiospecificity of H-atom Abstraction During the Hydroxylation and Cyclization Reactions Catalyzed by Hyoscyamine 6β-Hydroxylase.” J. Am. Chem. Soc. 2019, 141, 1062-1066. Ruszczycky, M. W.; Liu, H.-w. “Measurement of Net Rate Constants from Enzyme Progress Curves without Numerical Curve Fitting.” Biochemistry. 2019, 58, 4950-4956. [PMC6910778] Ren, D.; Ruszczycky, M. W.; Ko, Y.; Wang, S.-A.; Ogasawara, Y.; Kim, M.; Liu, H.-w. “Characterization of the Coformycin Biosynthetic Gene Cluster in Streptomyces kaniharaensis.” Proc. Natl. Aca. Sci. USA. 2020, 117, 10265-10270. [PMC7229688] Ruszczycky, M. W.; Liu, H.-w. “Distinguishing Concerted versus Stepwise Mechanisms Using Isotope Effects on Isotope Effects.” Biochemistry. 2021, 60, 3416-3418. [PMC 8612942] Besandre, R.; Chen, Z.; David, I.; Zhang, J.; Ruszczycky, M. W.; Liu, A.; Liu, H.-w. “HygY is a Twitch Radical SAM Epimerase with Latent Dehydrogenase Activity Revealed upon Mutation of a Single Cysteine Residue.” J. Am. Chem. Soc. 2021, 143, 15152-15158. [PMC8611816] Choi, S.-h.; Jeon, B.; Kim, N.; Wu, H.-H.; Ko, T.-P.; Ruszczycky, M. W.; Isiorho, E. A.; Liu, Y.-n.; Keatinge-Clay, A. T.; Tsai, M.-D.; Liu, H.-w. “Evidence for an Enzyme Catalyzed Rauhut-Currier Reaction during the Biosynthesis of Spinosyn A.” J. Am. Chem. Soc. 2021, 143, 20291-20295. [PMC8665079] Joen, B.-s.; Huang, T.-Y.; Ruszczycky, M. W.; Choi, S.-h.; Kim, N.; Franklin, J. L.; Hung, S.-C.; Liu, H.-w. “Byproduct Formation During the Biosynthesis of Spinosyn A and Evidence for an Enzymatic Interplay to Prevent its Formation.” Tetrahedron 2021, in press. [NIHMSID1759956] Lee, Y.-H.; Hou, X.; Chen, R.; Feng, J.; Liu, X.; Ruszczycky, M. W.; Guo, J.-M.; Wang, B.; Zhou, J.; Liu, H.-w. “Radical S-Adenosyl Methionine Enzyme BlsE Catalyzes a Radical Mediated 1,2-Diol Dehydration during the Biosynthesis of Blasticidin S.” J. Am. Chem. Soc. 2022, 4478-4486.[PMC8934444] Zhang, J.; Hou, X.; Chen, Z.; Ko, Y.; Ruszczycky, M. W.; Chen, Y.; Zhou, J,; Liu, H.-w. “Dioxane Bridge Formation in the Biosynthesis of Spectinomycin Involves a Twitch Radical SAM Dehydrogenase that Appears to Have Evolved from an Epimerase.” J. Am. Chem. Soc. 2022, 144, 9910-9919. [PMC9204835] De, B. C.; Zhang, W.; Yang, C.; Mándi, A.; Huang, C.; Zhang, L.; Liu, W.; Ruszczycky, M. W.; Zhu, Y.; Ma, M.; Bashiri, G.; Kurtán, T.; Liu, H.-w.; Changsheng Zhang, C. “Flavin-Enabled Reductive and Oxidative Epoxide Ring Opening Reactions.” Nature Commun. 2022, 11, 1-13. Lee, Y.-H.; Yeh, Y.-C.; Fan, P.-H.; Zhong, A.; Ruszczycky, M. W.; Liu, H.-w. “Changing Fates of the Substrate Radicals Generated in the Active Sites of the B12-dependent Radical SAM Enzymes OxsB and AlsB.” J. Am. Chem. Soc. 2023, 145, 3656-3664. [PMC9940012] Zheng, Z.; Lee, Y.-H.; Ruszczycky, M. W.; Ushimaru, R.; Liu, H.-w. “Twitch Radical S-Adenosyl L-Methionine Alcohol Dehydrogenases.” Encyclopedia Inorg. Bioinorg. Chem. 2024, eibc2869. [NIHMSID2015061] Ruszczycky, M. W.; Liu, H.-w. “Initiation, Propagation and Termination in the Chemistry of Radical SAM Enzymes.” Biochemistry, 2024, 63, 3161-3183. [PMC11878213] Ma, B.; Lee, Y.-H.; Ruszczycky, M. W.; Ren, D.; Engstrom, A.; Liu, H.-w.; Tao, L. “EPR Characterization of the BlsE Substrate Radical Offers Insight into the Determinants of Reaction Outcome that Distinguish Radical SAM Dioldehydratases from Dehydrogenases.” J. Am. Chem. Soc. 2025, 147, 4111-4119. [PMC11826333]
