Optically detected magnetic resonance study of tyrosine residues in point-mutated bacteriophage T4 lysozyme

Abstract

Two spectroscopically distinct types of tyrosine (Tyr) residues in triply point mutated bacteriophage T4 lysozyme, which contains no tryptophan (Trp), have been detected by optical detection of triplet-state magnetic resonance (ODMR) spectroscopy. Their triplet states are characterized by similar E but different D values. The Tyr site which exhibits the lower D value and has the red-shifted phosphorescence origin is quenched by energy transfer to Trp and has D and E values comparable to previously studied Tyr residues. The blue-shifted Tyr site, which is not quenched by Trp, exhibits a larger D value that has been found previously. Calculation of energy-transfer efficiencies of Tyr-Trp pairs based on the crystal structure of the native enzyme provides a possible assignment of Tyr sites to the two different spectral types.

Characterization of the Tryptophan Residues of Human Placental Ribonuclease Inhibitor and Its Complex with Bovine Pancreatic Ribonuclease A by Steady-State and Time-Resolved Emission Spectroscopy

“…This is consistent with very small ASA values of Trp109 in both the chains. Optically detected magnetic resonance (ODMR) studies in AP 23 and T4 lysozyme 22,23 also support the correlation of the position of the (0,0) bands with solvent exposure.…”

“…The quenching may be due to (i) energy transfer to another residue, (ii) interaction with a neighboring residue, for instance, the formation of a charge-transfer complex, or (iii) electron transfer from the excited state. However, several proteins containing more than one Trp residue are known to exhibit multiple (0,0) bands [21][22][23][24]45,46 arising from different Trp residues. The observation of multiple (0,0) bands is usually possible when the Trp residues in a protein are in widely different environments and photoinduced energy transfer among the emitting Trp residues is prevented.…”

A Comparative Study of Interaction of Tetracycline with Several Proteins Using Time Resolved Anisotropy, Phosphorescence, Docking and FRET

“…[20] In the case of free serum albumins and their complexes with TC, an unstructured underlying emission originating near 350 nm was observed in the spectrum, which is assigned to Tyr residues. [41] For AP-TC complex the contribution of tyrosine phosphorescence appearing below 400 nm was found to be diminished considerably. [20] This result thus indicates that Tyr residues are not involved in the ET process in the interaction between serum albumins and TC.…”

“…The tyrosine (Tyr) residues in proteins also exhibit a broad phosphorescence spectra within 350–450 nm region with λ exc  = 280 nm provided Tyr-Trp intramolecular energy transfer within the protein is prevented. [41].…”

Study ofl-tryptophan corepressor binding to mutatedE. coli tryptophan repressor proteins by optically detected triplet-state magnetic resonance

“…There are a number of cases, however, where individual Trp residues within a protein molecule exhibit resolved phosphorescence emission spectra [20][21][22][23]. In some situations of unresolved phosphorescence emission from two or more Trp residues, a technique of monitoring the ODMR frequency as a function of 0,0 band emission wavelength using narrow-bandpass conditions has been used successfully to distinguish multiple Trp sites [24][25][26][27].…”