Cyclotides are head-to-tail cyclic peptides in plants<\/p>\n
Cyclotides are plant-derived peptides of approximately 30 amino acids<\/strong>. They have the characteristic structural features of a head-to-tail cyclized backbone and a cystine knot arrangement of their three conserved disulfide bonds. Their unique structural features lead to exceptional stability. This and their amenability to chemical synthesis have made it possible to use cyclotides as templates in protein engineering and drug design applications.<\/p>\n David J Craik, University of Queensland, Brisbane, Australia, whose laboratory is working over 20 years in the field, summarizes the history of cyclotides<\/p>\n Read more<\/a><\/p>\n http:\/\/www.chemistryviews.org\/details\/news\/5012211\/History_of_Cyclotides.html<\/a><\/p>\n <\/p>\n more info on cyclotides<\/p>\n <\/a> Cyclotides are small disulfide-rich proteins that have the unusual feature of a cyclic backbone (hence the name\u00a0cyclo<\/strong>\u00a0– peptides<\/strong>). They contain six conserved cystine residues that are arranged in a cystine knot topology in which two disulfide bonds and their connecting backbone segments form an embedded ring in the structure that is penetrated by a third disulfide bond, as shown below.<\/p>\n Cyclotides have a range of interesting biological activities including anti-HIV and neurotensin inhibition, anti-microbial activity and insecticidal activity. They are found in a variety of tropical plants from the Rubiaceae and Violaceae families.<\/p>\n
\nFigure 1. Structure and sequence of the prototypic cyclotide kalata B1<\/p>\n