6o4m
Racemic melittin
Structural highlights
FunctionMEL_APIME Melittin: Main toxin of bee venom with strong hemolytic activity. Forms a pore in the cell membrane by inserting into lipid bilayers in an alpha-helical conformation and has multiple effects, probably, as a result of its interaction with negatively charged phospholipids. It inhibits well known transport pumps such as the Na(+)-K(+)-ATPase and the H(+)-K(+)-ATPase. It increases the permeability of cell membranes to ions, particularly Na(+) and indirectly Ca(2+), because of the Na(+)-Ca(2+)-exchange. It acts synergistically with phospholipase A2.[1] Melittin-S: 1.4-fold less hemolytic and adopts a less organized secondary structure than melittin.[2] Publication Abstract from PubMedRacemic crystallography has been used to elucidate the secondary and tertiary structures of peptides and small proteins that are recalcitrant to conventional crystallization. It is unclear, however, whether racemic crystallography can capture native quaternary structure, which could be disrupted by heterochiral associations. We are exploring the use of racemic crystallography to characterize the self-assembly behavior of membrane-associated peptides, very few of which have been crystallized. We report a racemic crystal structure of the membrane-active peptide melittin; the new structure allows comparison with a previously reported crystal structure of L-melittin. The tetrameric assembly observed in crystalline L-melittin has been proposed to represent the tetrameric state detected in solution for this peptide. This tetrameric assembly is precisely reproduced in the racemic crystal, which strengthens the conclusion that the tetramer is biologically relevant. More broadly, these findings suggest that racemic crystallography can provide insight on native quaternary structure. Retention of Native Quaternary Structure in Racemic Melittin Crystals.,Kurgan KW, Kleman AF, Bingman CA, Kreitler DF, Weisblum B, Forest KT, Gellman SH J Am Chem Soc. 2019 May 15;141(19):7704-7708. doi: 10.1021/jacs.9b02691. Epub, 2019 May 6. PMID:31059253[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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