1bh4

<StructureSection load='1bh4' size='340' side='right'caption='[[1bh4]], [[NMR_Ensembles_of_Models | 12 NMR models]]' scene=''>

<table><tr><td colspan='2'>[[1bh4]] is a 1 chain structure with sequence from [http://en.wikipedia.org/wiki/Chassalia_parviflora Chassalia parviflora]. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1BH4 OCA]. For a <b>guided tour on the structure components</b> use [http://proteopedia.org/fgij/fg.htm?mol=1BH4 FirstGlance]. <br>

</td></tr><tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://proteopedia.org/fgij/fg.htm?mol=1bh4 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1bh4 OCA], [http://pdbe.org/1bh4 PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=1bh4 RCSB], [http://www.ebi.ac.uk/pdbsum/1bh4 PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=1bh4 ProSAT]</span></td></tr>

[[http://www.uniprot.org/uniprot/CIRA_CHAPA CIRA_CHAPA]] Probably participates in a plant defense mechanism. Has antibiotic activity. Inhibits the cytopathic effects and replication of the human immunodeficiency virus. Active against the Gram-positive S.aureus with a minimum inhibition concentration of approximately 0.2 microM. Relatively ineffective against Gram-negative bacteria such as E.coli and P.aeruginosa.

<div style="background-color:#fffaf0;">

== Publication Abstract from PubMed ==

The three-dimensional solution structure of circulin A, a 30 residue polypeptide from the African plant Chassalia parvifolia, has been determined using two-dimensional 1H-NMR spectroscopy. Circulin A was originally identified based upon its inhibition of the cytopathic effects and replication of the human immunodeficiency virus. Structural restraints consisting of 369 interproton distances inferred from nuclear Overhauser effects, and 21 backbone dihedral and nine chi1 angle restraints from spin-spin coupling constants were used as input for simulated annealing calculations and energy minimisation in the program X-PLOR. The final set of 12 structures had mean pairwise rms differences over the whole molecule of 0.91 A for the backbone atom, and 1.68 A for all heavy atoms. For the well-defined region encompassing residues 2-12 and 18-27, the corresponding values were 0.71 and 1.66 A, respectively. Circulin A adopts a compact structure consisting of beta-turns and a distorted segment of triple-stranded beta-sheet. Fluorescence spectroscopy provided additional evidence for a solvent-exposed Trp residue. The molecule is stabilised by three disulfide bonds, two of which form an embedded loop completed by the backbone fragments connecting the cysteine residues. A third disulfide bond threads through the centre of this loop to form a "cystine-knot" motif. This motif is present in a range of other biologically active proteins, including omega-contoxin GVIA and Cucurbita maxima trypsin inhibitor. Circulin A belongs to a novel class of macrocyclic peptides which have been isolated from plants in the Rubiaceae family. The global fold of circulin A is similar to kalata B1, the only member of this class for which a structure has previously been determined.

Solution structure by NMR of circulin A: a macrocyclic knotted peptide having anti-HIV activity.,Daly NL, Koltay A, Gustafson KR, Boyd MR, Casas-Finet JR, Craik DJ J Mol Biol. 1999 Jan 8;285(1):333-45. PMID:9878410<ref>PMID:9878410</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

</div>

<div class="pdbe-citations 1bh4" style="background-color:#fffaf0;"></div>

== References ==

<references/>

[[Category: Craik, D J]]

[[Category: Daly, N L]]

[[Category: Koltay, A]]

[[Category: Cystine knot]]