1nbl
From Proteopedia
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NMR Structure of Hellethionin D
Overview
Thionins are relatively small-sized multiple-cystine peptides that are, probably involved in the plant defense against pathogens. As such, these, peptides constitute promising candidates for engineered plant resistance, in the agricultural industry. More recently, thionins have been proposed, as potential immunotoxins in tumor therapy. In the search for, pharmacologically active natural products, a new family of thionins was, recently discovered in the roots of Helleborus purpurascens that, accordingly were termed hellethionins. The structural characterization by, NMR of one representative member of this family, i.e., of hellethionin D, clearly reveals that thionins from different sources share a highly, conserved overall fold. In fact, the well-defined 3D structure of, hellethionin D is very similar to those reported so far for viscotoxins, purothionins, or crambin, although distinct differences could be detected, in the C-terminal portion, especially for loop 36-39. These differences, may derive from the unusual distribution of charged residues in the, C-terminal half of the peptide sequence compared to other thionins and, from the uncommon occurrence of four contiguous threonine residues in loop, 36-39. As expected, reduction of the disulfide bonds in hellethionin D, leads to complete unfolding, but upon oxidative refolding by air oxygen in, the presence of glutathione the correct isomer is recovered in high, yields, confirming the very robust fold of this class of bioactive cystine, peptides.
About this Structure
1NBL is a Protein complex structure of sequences from Helleborus purpurascens. Full crystallographic information is available from OCA.
Reference
Structural characterization of hellethionins from Helleborus purpurascens., Milbradt AG, Kerek F, Moroder L, Renner C, Biochemistry. 2003 Mar 4;42(8):2404-11. PMID:12600207
Page seeded by OCA on Tue Nov 20 22:07:16 2007
