Articolo in rivista, 1992, ENG, 10.1111/j.1432-1033.1992.tb17345.x

CHARACTERIZATION OF TRYPTOPHAN PHOSPHORESCENCE OF ASPARTATE-AMINOTRANSFERASE FROM ESCHERICHIA-COLI

CIONI, P; ONUFFER, JJ; STRAMBINI, GB

Istituto di Biofisica CNR

The Trp phosphorescence spectrum, intensity and decay kinetics of apo-aspartate aminotransferase, pyridoxamine-5P-aspartate-aminotransferase and pyridoxal-5P-aspartate aminotransferase were measured over a temperature range 160-273 K. The fine structure of the phosphorescence spectra in low-temperature glasses, with 0-0 vibrational bands centered at 408, 415 and 417 nm, for both apoenzyme and pyridoxamine-5P-enzyme reveals a marked heterogeneity of the chromophore environments. Only for the pyridoxal-5P form of the enzyme is the triplet emission strongly quenched and, in this case, the spectrum displays a unique 0-0 vibrational band centered at 415 nm. Concomitant to quenching, there is Trp-sensitized delayed fluorescence of the Schiff base, an indication that quenching of the excited triplet state is due, at least in part, to a process of triplet singlet energy transfer to the ketoenamine tautomer.

European journal of biochemistry (Print) 209 (2), pp. 759–764

Keywords

Trp phosphorescence, aspartate aminotransferase

CNR authors

Strambini Giovanni Battista, Cioni Patrizia

CNR institutes

ID: 349629

Year: 1992

Type: Articolo in rivista

Creation: 2016-03-04 12:38:05.000

Last update: 2016-03-04 12:38:05.000

External links

OAI-PMH: Dublin Core

OAI-PMH: Mods

OAI-PMH: RDF

DOI: 10.1111/j.1432-1033.1992.tb17345.x

External IDs

CNR OAI-PMH: oai:it.cnr:prodotti:349629

DOI: 10.1111/j.1432-1033.1992.tb17345.x

ISI Web of Science (WOS): A1992JX22200033