title: Comparison of the time-resolved absorption and phosphorescence from the tryptophan triplet state in proteins in solution.
abstract: Measurement of the room temperature Trp triplet state lifetime in proteins by time-resolved phosphorescence can provide valuable information on the structure and dynamics of proteins in solution. Our time-resolved absorption measurements on the long-lived states resulting from electronic excitation of the chromophore demonstrate the presence of more complex behavior than revealed by time-resolved phosphorescence. To provide additional insight into this behavior, a comparative study of time-resolved transient absorption and time-resolved phosphorescence of proteins in solution was carried out. The results show that the time evolution of the long-lived states observed through transient absorption often differs considerably from that observed in time-resolved phosphorescence. In some proteins, the presence of competing reactions complicates the interpretation of the transient absorption measurements (which may affect the phosphorescence yield). A more complete characterization of these processes will likely prove useful in the study of protein structure and dynamics in solution.
authors.affiliation: Institute of Gerontology, University of Michigan, Ann Arbor 48109, USA.
authors.forename: A
authors.initials: A
authors.lastname: Gershenson
authors.forename: A
authors.initials: A
authors.lastname: Gafni
authors.forename: D
authors.initials: D
authors.lastname: Steel
mesh_terms: D000469:Alkaline Phosphatase / Q000737:chemistry; D000818:Animals; D001400:Azurin / Q000737:chemistry; D004798:Enzymes / Q000737:chemistry*; D007700:Kinetics; D049449:Luminescence; D010735:Phosphoglycerate Kinase / Q000737:chemistry; D011506:Proteins / Q000737:chemistry*; D012996:Solutions; D013053:Spectrophotometry / Q000295:instrumentation / Q000379:methods; D013997:Time Factors; D014364:Tryptophan / Q000737:chemistry*
chemical_list: D004798:Enzymes; D011506:Proteins; D012996:Solutions; D001400:Azurin; D014364:Tryptophan; D010735:Phosphoglycerate Kinase; D000469:Alkaline Phosphatase