Trapping specific quaternary states of the allosteric enzyme aspartate transcarbamoylase in silica matrix sol-gels |
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Authors: | West Jay M Kantrowitz Evan R |
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Affiliation: | Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, MA 02467, USA. |
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Abstract: | The extreme T and R quaternary structures of the allosteric enzyme aspartate transcarbamoylase have been trapped by encapsulation in a silica sol-gel matrix. Detection of the specific quaternary structure present in the sol-gel was accomplished using a pyrene-labeled version of the enzyme that exhibited monomer fluorescence in the T quaternary structure and excimer fluorescence in the R quaternary structure. Using thin films of the encapsulated enzyme, kinetics of the T and R states could be determined without interconversion of the states. Using a monolith form of the encapsulated enzyme, the transition from the T or the R structure was monitored. Within the sol-gel matrix, the rate of the transition was slowed approximately 105 over that observed in solution. |
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