Structural and functional characterization of second-coordination sphere mutants of soybean lipoxygenase-1.Tomchick, D.R., Phan, P., Cymborowski, M., Minor, W., Holman, T.R.
(2001) Biochemistry 40: 7509-7517
- PubMed: 11412104
- Primary Citation of Related Structures:  1F8N, 1FGM, 1FGQ, 1FGR, 1FGT
- PubMed Abstract:
- NATURE OF THE RATE-LIMITING STEPS IN THE SOYBEAN LIPOXYGENASE-1 REACTION
GLICKMAN, M.H.,KLINMAN, J.P.
(1995) Biochemistry 34: 14077
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MINOR, W.,STECZKO, J.,BOLIN, J.T.,OTWINOWSKI, Z.,AXELROD, B.
(1993) Biochemistry 32: 6320
- CRYSTAL STRUCTURE OF SOYBEAN LIPOXYGENASE L-1 AT 1.4 A RESOLUTION
MINOR, W.,STECZKO, J.,STEC, B.,OTWINOWSKI, Z.,BOLIN, J.T.,WALTER, R.,AXELROD, B.
(1996) Biochemistry 35: 10687
- THE STRUCTURE AND FUNCTION OF LIPOXYGENASE
NELSON, M.J.,SEITZ, S.P.
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- CRYSTALLIZATION AND PRELIMINARY X-RAY INVESTIGATION OF LIPOXYGENASE 1 FROM SOYBEANS
STECZKO, J.,MUCHMORE, C.R.,L SMITH, J.,AXELROD, B.
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- THE THREE-DIMENSIONAL STRUCTURE OF AN ARACHIDONIC ACID 15-LIPOXYGENASE
BOYINGTON, J.C.,GAFFNEY, B.J.,AMZEL, L.M.
(1993) Science 260: 1482
- EXPERIMENTAL EVIDENCE FOR EXTENSIVE TUNNELING OF HYDROGEN IN THE LIPOXYGENASE REACTION: IMPLICATIONS FOR ENZYME CATALYSIS
JONSSON, T.,GLICKMAN, M.H.,SUN, S.,KLINMAN, J.P.
(1996) J.Am.Chem.Soc. 118: 10319
Lipoxygenases are an important class of non-heme iron enzymes that catalyze the hydroperoxidation of unsaturated fatty acids. The details of the enzymatic mechanism of lipoxygenases are still not well understood. This study utilizes a combination of ...
Lipoxygenases are an important class of non-heme iron enzymes that catalyze the hydroperoxidation of unsaturated fatty acids. The details of the enzymatic mechanism of lipoxygenases are still not well understood. This study utilizes a combination of kinetic and structural probes to relate the lipoxygenase mechanism of action with structural modifications of the iron's second coordination sphere. The second coordination sphere consists of Gln(495) and Gln(697), which form a hydrogen bond network between the substrate cavity and the first coordination sphere (Asn(694)). In this investigation, we compared the kinetic and structural properties of four mutants (Q495E, Q495A, Q697N, and Q697E) with those of wild-type soybean lipoxygenase-1 and determined that changes in the second coordination sphere affected the enzymatic activity by hydrogen bond rearrangement and substrate positioning through interaction with Gln(495). The nature of the C-H bond cleavage event remained unchanged, which demonstrates that the mutations have not affected the mechanism of hydrogen atom tunneling. The unusual and dramatic inverse solvent isotope effect (SIE) observed for the Q697E mutant indicated that an Fe(III)-OH(-) is the active site base. A new transition state model for hydrogen atom abstraction is proposed.
Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia 22908, USA.