Ultrafast Polarized Fluorescence Measurements on Monomeric and Self-Associated Melittin

Pandit, Anjali; Larsen, Olaf F. A.; Stokkum, Ivo H. M. van; Grondelle, Rienk van; Kraayenhof, Ruud; Amerongen, Herbert van

doi:10.1021/jp021757a

Cited by 12 publications

(13 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, the fast rotational correlation time we find (155 ps) is much faster than the isotropic ∼500 ps; no correlation between the isotropic decay times and the anisotropic decay times as suggested by Lakowicz is found. Similar results have been found for ultrafast fluorescence studies on the single-Trp peptide melittin …”

Section: Discussionsupporting

confidence: 87%

See 1 more Smart Citation

Ultrafast Polarized Fluorescence Measurements on Tryptophan and a Tryptophan-Containing Peptide

et al. 2003

Self Cite

View full text Add to dashboard Cite

In this work polarized picosecond fluorescence measurements were performed on isolated tryptophan and tryptophan in a small 22-mer peptide using a streak camera coupled to a spectrograph as a detection system. In both cases the fluorescence decay was multiexponential with decay times of ∼500 ps and ∼4 ns. Surprisingly, also a short-lived (∼16 ps) isotropic fluorescence component was found for both tryptophan and the peptide which, to our knowledge, has never been observed before. Fluorescence anisotropy data showed rotational correlation times of 155 ps and 1.5 ns for the peptide, reflecting local and overall peptide dynamics, respectively. Recently it was argued [Lakowicz, J. R. Photochem. Photobiol. 2000, 72, 421] that the nonexponential fluorescence decay of tryptophan in proteins is mainly due to spectral relaxation, whereas for isolated tryptophan it is due to different rotamers. Our results do not support this view. In contrast we conclude in both cases that the different fluorescence decay times should be ascribed to different rotameric states.

show abstract

Section: Discussionsupporting

confidence: 87%

“…Similar results have been found for ultrafast fluorescence studies on the singleTrp peptide melittin. 29 …”

Section: Discussionmentioning

confidence: 99%

Ultrafast Polarized Fluorescence Measurements on Tryptophan and a Tryptophan-Containing Peptide

et al. 2003

Self Cite

View full text Add to dashboard Cite

show abstract

“…3 and are shown in Table 2. As can be seen from the table, the mean fluorescence lifetime of monomeric melittin in aqueous solution is 3.5 ns, in agreement with previous literature (McDowell et al 1985;Pandit et al 2003). The mean fluorescence lifetimes of melittin in micelles of various surface charges are different, indicating that the local environment experienced by the tryptophan residue is different in these cases.…”

Section: Fluorescence Polarization Of Micelle-bound Melittinsupporting

confidence: 91%

Effect of micellar charge on the conformation and dynamics of melittin

Raghuraman

Chattopadhyay

2004

Eur Biophys J

View full text Add to dashboard Cite

Electrostatic interactions play a crucial role in modulating and stabilizing molecular interactions in membranes and membrane-mimetic systems such as micelles. We have monitored the change in the conformation and dynamics of the cationic hemolytic peptide melittin bound to micelles of various charge types, utilizing fluorescence and circular dichroism (CD) spectroscopy. The sole tryptophan of melittin displays a red-edge excitation shift (REES) of 3-6 nm when bound to anionic, nonionic, and zwitterionic micelles. This suggests that melittin is localized in a restricted environment, probably in the interfacial region of the micelles, and this region offers considerable restriction to the reorientational motion of the solvent dipoles around the excited state tryptophan in melittin. Further, the rotational mobility of melittin is considerably reduced in these micelles and is found to be dependent on the surface charge of micelles. Interestingly, our results show that melittin does not partition into cetyltrimethylammonium bromide (CTAB) micelles owing to electrostatic repulsion between melittin and CTAB micelles, both of which carry a positive charge. In addition, the fluorescence lifetime of melittin is modulated in micelles of different charge types. The lowest mean fluorescence lifetime is observed in the case of melittin bound to anionic sodium dodecyl sulfate (SDS) micelles. CD spectroscopy shows that micelles induce significant helicity to melittin, with maximum helicity being induced in the case of melittin bound to SDS micelles. Fluorescence quenching measurements using the neutral aqueous quencher acrylamide show differential accessibility of melittin in various types of micelles. Taken together, our results show that micellar surface charge can modulate the conformation and dynamics of melittin. These results could be relevant to understanding the role of the surface charge of membranes in the interaction of membrane-active, amphiphilic peptides with membranes.

show abstract

“…The lifetime of the tryptophan residue of the monomeric melittin in buffer is * 2.9 ns, similar to previously reported values. 13,40,41 As shown in the figure, there is a sharp decrease in the mean fluorescence lifetime of the tryptophan residue(s) of melittin upon increasing the NaCl to 0.8 M. In general, a decrease in polarity of the tryptophan environment is known to increase the fluorescence lifetime of tryptophans due to fast deactivating processes in polar environments. 36 …”

Section: Fluorescence Polarization and Lifetime Measurements Of Melitmentioning

confidence: 91%

Effect of ionic strength on folding and aggregation of the hemolytic peptide melittin in solution

Raghuraman

Chattopadhyay

2006

Biopolymers

View full text Add to dashboard Cite

Melittin is a cationic, amphipathic, hemolytic peptide composed of 26 amino acid residues. It is intrinsically fluorescent due to the presence of a single tryptophan residue, which has been shown to be crucial for its hemolytic activity. It undergoes a structural transition from a random coil monomer to an alpha-helical tetramer at high ionic strength. Although the aggregation behavior of melittin in solution is well characterized, dynamic information associated with the aggregation of melittin is lacking. In this paper, we have monitored the effect of ionic strength on the dynamics and aggregation behavior of melittin in aqueous solution by utilizing sensitive fluorescence approaches, which include the red edge excitation shift (REES) approach. Importantly, we demonstrate that REES is sensitive to the self-association of melittin induced by ionic strength. The change in environment experienced by melittin tryptophan(s) is supported by changes in fluorescence emission maximum, polarization, and lifetime. In addition, the accessibility of the tryptophan residue was probed by fluorescence quenching experiments using acrylamide and trichloroethanol as soluble and hydrophobic quenchers, respectively. Circular dichroism studies confirm the ionic strength-induced change in the secondary structure of melittin. Taken together, these results constitute the first report showing that REES could be used as a sensitive tool to monitor the aggregation behavior of melittin in particular and other proteins and peptides in general.

show abstract

Ultrafast Polarized Fluorescence Measurements on Monomeric and Self-Associated Melittin

Cited by 12 publications

References 30 publications

Ultrafast Polarized Fluorescence Measurements on Tryptophan and a Tryptophan-Containing Peptide

Ultrafast Polarized Fluorescence Measurements on Tryptophan and a Tryptophan-Containing Peptide

Effect of micellar charge on the conformation and dynamics of melittin

Effect of ionic strength on folding and aggregation of the hemolytic peptide melittin in solution

Contact Info

Product

Resources

About