Publications

• Large-scale domain motions and pyridoxal-5'-phosphate assisted radical catalysis in coenzyme B12-dependent aminomutases.

  Maity A.N., Chen Y.H., Ke S.C.

  Lysine 5,6-aminomutase (5,6-LAM) and ornithine 4,5-aminomutase (4,5-OAM) are two of the rare enzymes that use assistance of two vitamins as cofactors. These enzymes employ radical generating capability of coenzyme B12 (5'-deoxyadenosylcobalamin, dAdoCbl) and ability of pyridoxal-5'-phosphate (PLP, ... >> More

  Lysine 5,6-aminomutase (5,6-LAM) and ornithine 4,5-aminomutase (4,5-OAM) are two of the rare enzymes that use assistance of two vitamins as cofactors. These enzymes employ radical generating capability of coenzyme B12 (5'-deoxyadenosylcobalamin, dAdoCbl) and ability of pyridoxal-5'-phosphate (PLP, vitamin B6) to stabilize high-energy intermediates for performing challenging 1,2-amino rearrangements between adjacent carbons. A large-scale domain movement is required for interconversion between the catalytically inactive open form and the catalytically active closed form. In spite of all the similarities, these enzymes differ in substrate specificities. 4,5-OAM is highly specific for D-ornithine as a substrate while 5,6-LAM can accept D-lysine and L-β-lysine. This review focuses on recent computational, spectroscopic and structural studies of these enzymes and their implications on the related enzymes. Additionally, we also discuss the potential biosynthetic application of 5,6-LAM. << Less

  Int J Mol Sci 15:3064-3087(2014) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.

• Pathway of lysine degradation in Fusobacterium nucleatum.

  Barker H.A., Kahn J.M., Hedrick L.

  Lysine was fermented by Fusobacterium nucleatum ATCC 25586 with the formation of about 1 mol each of acetate and butyrate. By the use of [1-14C]lysine or [6-14C]lysine, acetate and butyrate were shown to be derived from both ends of lysine, with acetate being formed preferentially from carbon atom ... >> More

  Lysine was fermented by Fusobacterium nucleatum ATCC 25586 with the formation of about 1 mol each of acetate and butyrate. By the use of [1-14C]lysine or [6-14C]lysine, acetate and butyrate were shown to be derived from both ends of lysine, with acetate being formed preferentially from carbon atoms 1 and 2 and butyrate being formed preferentially from carbon atoms 3 to 6. This indicates that the lysine carbon chain is cleaved between both carbon atoms 2 and 3 and carbon atoms 4 and 5, with the former predominating [1-14C]acetate was also extensively incorporated into butyrate, preferentially into carbon atoms 3 and 4. Cell-free extracts of F. nucleatum were shown to catalyze the reactions of the 3-keto,5-aminohexanoate pathway of lysine degradation, previously described in lysine-fermenting clostridia. The 3-keto,5-aminohexanoate cleavage enzyme was partially purified and shown to have properties much like those of the clostridial enzyme. We conclude that both the pathway and the enzymes of lysine degradation are similar in F. nucleatum and lysine-fermenting clostridia. << Less

  J. Bacteriol. 152:201-207(1982) [PubMed] [EuropePMC]

  This publication is cited by 4 other entries.

• Radical stabilization is crucial in the mechanism of action of lysine 5,6-aminomutase: role of tyrosine-263alpha as revealed by electron paramagnetic resonance spectroscopy.

  Chen Y.H., Maity A.N., Pan Y.C., Frey P.A., Ke S.C.

  Adenosylcobalamin- and pyridoxal-5'-phosphate-dependent lysine 5,6-aminomutase utilizes free radical intermediates to mediate 1,2-amino group rearrangement, during which an elusive high-energy aziridincarbinyl radical is proposed to be central in the mechanism of action. Understanding how the enzy ... >> More

  Adenosylcobalamin- and pyridoxal-5'-phosphate-dependent lysine 5,6-aminomutase utilizes free radical intermediates to mediate 1,2-amino group rearrangement, during which an elusive high-energy aziridincarbinyl radical is proposed to be central in the mechanism of action. Understanding how the enzyme participates in stabilizing any of the radical intermediates is fundamentally significant. Y263F mutation abolished the enzymatic activity. With isotope-edited EPR methods, the roles of the Tyr263α residue in the putative active site are revealed. The Tyr263α residue stabilizes a radical intermediate, which most likely is the aziridincarbinyl radical, either by acting as a spin-relay device or serving as an anchor for the pyridine ring of pyridoxal-5'-phosphate through aromatic π-stacking interactions during spin transfer. The Tyr263α residue also protects the radical intermediate from interception by molecular oxygen. This study supports the proposed reaction mechanism, including the aziridincarbinyl radical, which has eluded detection for more than two decades. << Less

  J Am Chem Soc 133:17152-17155(2011) [PubMed] [EuropePMC]