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Long-lived tryptophan fluorescence in phosphoglycerate mutase
1Institute of Gerontology, University of Michigan, Ann Arbor 48109.
Biochemistry
|May 2, 1989
Summary
Phosphoglycerate mutase (PGM) from rabbit muscle exhibits a unique long-lived fluorescence from a tryptophan residue. This unusual fluorescence is sensitive to protein environment but absent in yeast PGM.
Area of Science:
- Biochemistry
- Biophysics
- Enzymology
Background:
- Phosphoglycerate mutase (PGM) is a crucial enzyme in glycolysis.
- Mammalian PGM exhibits unique fluorescence properties not observed in other species.
Purpose of the Study:
- To investigate the source and characteristics of the unusually long-lived fluorescence in rabbit muscle PGM.
- To compare the fluorescence properties of mammalian PGM with its yeast counterpart.
Main Methods:
- Time-resolved tryptophan fluorescence spectroscopy
- Enzyme activity assays
- Fluorescence quenching studies with ions and acrylamide
Main Results:
- A 16.4 ns fluorescence lifetime component was identified in rabbit muscle PGM, attributed to a tryptophan in an unusual environment.
- This long-lived fluorescence is red-shifted and sensitive to denaturation and refolding.
- Yeast PGM lacks this long-lived fluorescence component.
- The tryptophan is marginally solvent-accessible and quenched by specific ions.
Conclusions:
- The long-lived fluorescence in rabbit muscle PGM originates from a tryptophan residue in a unique protein microenvironment.
- This fluorescence is not due to covalent modification and is dependent on the protein's native structure.
- Differences in fluorescence properties may reflect structural or functional variations between mammalian and yeast PGM.