Effects of lipid fluidity on quenching characteristics of tryptophan fluorescence in yeast plasma membrane.
Fluorescence characteristics of tryptophan residues in yeast plasma membrane indicate that the residues are buried. The fluorescence is fully quenchable by iodide with similar quenching kinetics at temperatures from 8 to 37 degrees C in oleate-enriched membranes and from 25 to 37 degrees C in palmitelaidate-enriched membranes. Substantial increases in lipid microviscosity in palmitelaidate-enriched membranes reduce the fraction of quenchable tryptophan fluorescence by about 40% and increase the effective quenching constant 3-fold. These observations indicate that at above 25 degrees C, proteins in this membrane undergo transient conformational changes and that freedom of conformational changes of the proteins is regulated by lipid microviscosity.
D002462:Cell Membrane / Q000032:analysis*; D019791:Guanidine; D006146:Guanidines; D007700:Kinetics; D008560:Membrane Fluidity; D008565:Membrane Proteins / Q000032:analysis*; D012441:Saccharomyces cerevisiae / Q000032:analysis*; D013050:Spectrometry, Fluorescence; D013696:Temperature; D014364:Tryptophan / Q000032:analysis*
D006146:Guanidines; D008565:Membrane Proteins; D014364:Tryptophan; D019791:Guanidine