Structure-fluorescence correlations in a single tryptophan mutant of carp parvalbumin: solution structure, backbone and side-chain dynamics

摘要: Abstract Heterogeneous fluorescence intensity decays of tryptophan in proteins are often rationalized using a model which proposes that different rotameric states the indole alanyl side-chain responsible for observed lifetime heterogeneity. We present here study mutant carp parvalbumin bearing single residue at position 102 (F102W) whose decay is heterogeneous and assess applicability rotamer to describe data. have determined solution structure F102W calcium ligated state multi-dimensional nuclear magnetic resonance (NMR) used minimum perturbation mapping technique explore possible existence multiple conformations moiety Trp102 and, comparison, Trp48 holo-azurin. The maps suggest two potential side-chain. high energy barrier rotational isomerization between these conformers implies interwell rotation would occur on time-scales milliseconds or greater suggests basis fluorescence. However, absence alternate NMR data (to within 3 % dominant species) may arise from mechanisms independent Trp map holo-azurin has only one conformation, not be required explain its decay. backbone dynamics 30 °C been characterized based an analysis 15 N relaxation we interpreted Lipari-Szabo formalism. High order parameter ( S 2 ) values were obtained both helical loop regions. Additionally, imply binding CD EF loops strictly equivalent. value fluorescence, consistent with motion restricted.