Mechanism of the conformational transition of melittin.


It is known that, while melittin at micromolar concentrations is unfolded under conditions of low ionic strength at neutral pH, it adopts a tetrameric alpha-helical structure under conditions of high ionic strength, at alkaline pH, or at high peptide concentrations. To understand the mechanism of the conformational transition of melittin, we examined in detail the conformation of melittin under various conditions by far-UV circular dichroism at 20 degrees C. We found that the helical conformation is also stabilized by strong acids such as perchloric acid. The effects of various acids varied largely and were similar to those of the corresponding salts, indicating that the anions are responsible for the salt- or acid-induced transitions. The order of effectiveness of various monovalent anions was consistent with the electroselectivity series of anions toward anion-exchange resins, indicating that the anion binding is responsible for the salt- or acid-induced transitions. From the NaCl-, HCl-, and alkaline pH-induced conformational transitions, we constructed a phase diagram of the anion- and pH-dependent conformational transition. The phase diagram was similar in shape to that of acid-denatured apomyoglobin [Goto, Y., & Fink, A.L. (1990) J. Mol. Biol. 214, 803-805] or that of the amphiphilic Lys, Leu model polypeptide [Goto, Y., & Aimoto, S. (1991) J. Mol. Biol. 218, 387-396], suggesting a common mechanism of the conformational transition. The anion-, pH-, and peptide concentration-dependent conformational transition of melittin was explained on the basis of an equation in which the conformational transition is linked to proton and anion binding to the titratable groups. Study holds ProTherm entries: 3971 Extra Details: alpha-helical structure; conformational transition ;,electroselectivity; phase diagram; anion binding

Submission Details

ID: gnbto9Q53

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:23 p.m.

Version: 1

Publication Details
Goto Y;Hagihara Y,Biochemistry (1992) Mechanism of the conformational transition of melittin. PMID:1731930
Additional Information

Study Summary

Number of data points 1
Proteins Melittin ; Melittin
Unique complexes 1
Assays/Quantities/Protocols Experimental Assay: dG
Libraries Mutations for sequence GIGAVLKVLTTGLPALISWIKRKRQQ

Structure view and single mutant data analysis

Study data

No weblogo for data of varying length.
Colors: D E R H K S T N Q A V I L M F Y W C G P

Data Distribution

Studies with similar sequences (approximate matches)

Correlation with other assays (exact sequence matches)

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
100.0 Melittin P01501 MEL_APIME
100.0 Melittin P59262 MEL_VESMC
98.6 Melittin P0DPR9 MELN_APICE
100.0 Melittin P68407 MEL_APICC
100.0 Melittin P68408 MEL_VESMG
100.0 Melittin P68409 MEL_VESVN
95.8 Melittin P59261 MEL_POLHE
100.0 Melittin Q8LW54 MELS_APICE