Shepherd, Mark and Hunter, C.N. (2004) Transient kinetics of the reaction catalysed by magnesium protoporphyrin IX methyltransferase. The Biochemical journal, 382 (Pt 3). pp. 1009-13. ISSN 1470-8728.
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Abstract
Magnesium protoporphyrin IX methyltransferase (ChlM), an enzyme in the chlorophyll biosynthetic pathway, catalyses the transfer of a methyl group to magnesium protoporphyrin IX (MgP) to form magnesium protoporphyrin IX monomethyl ester (MgPME). S-Adenosyl-L-methionine is the other substrate, from which a methyl group is transferred to the propionate group on ring C of the porphyrin macrocycle. Stopped-flow techniques were used to characterize the binding of porphyrin substrate to ChlM from Synechocystis PCC6803 by monitoring tryptophan fluorescence quenching on a millisecond timescale. We concluded that a rapid binding step is preceded by a slower isomerization of the enzyme. Quenched-flow techniques have been employed to characterize subsequent partial reactions in the catalytic mechanism. A lag phase has been identified that has been attributed to the formation of an intermediate. Our results provide a greater understanding of this catalytic process which controls the relative concentrations of MgP and MgPME, both of which are implicated in signalling between the plastid and nucleus in plants.
| Item Type: | Article |
|---|---|
| Subjects: | Q Science |
| Divisions: | Faculties > Science Technology and Medical Studies > School of Biosciences |
| Depositing User: | Mark Shepherd |
| Date Deposited: | 01 Sep 2011 16:11 |
| Last Modified: | 27 Jun 2012 09:21 |
| Resource URI: | http://kar.kent.ac.uk/id/eprint/28094 (The current URI for this page, for reference purposes) |
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