Trapping specific quaternary states of the allosteric enzyme aspartate transcarbamoylase in silica matrix sol-gels.
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.
West
Jay M
JM
Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, MA 02467, USA.
Kantrowitz
Evan R
ER
D001221:Aspartate Carbamoyltransferase / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D003570:Cytidine Triphosphate / Q000737:chemistry; D004800:Enzymes, Immobilized / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology; D005782:Gels; D007700:Kinetics; D011487:Protein Conformation; D012542:Scattering, Radiation; D012996:Solutions; D013050:Spectrometry, Fluorescence; D014544:Uridine Triphosphate / Q000737:chemistry; D014965:X-Rays
D004800:Enzymes, Immobilized; D005782:Gels; D012996:Solutions; D003570:Cytidine Triphosphate; D001221:Aspartate Carbamoyltransferase; D014544:Uridine Triphosphate