A bicyclic undecapeptide of sequence cyclo-(Ala(1)-Pro(2)-Asp(3)-Glu(4)-Lys(5)-Ala(6)-Pro(7)-Asp(8)-Ser(9) -Glu(10))-cyclo-(10gamma --> 5varepsilon)-Gly(11), designed to mimic the calcium coordination site I of Calmodulin, has been synthesized and its conformation and calcium binding properties have
Bicyclic peptides. V. Conformation and ion binding of an undeca and a dodeca bicyclic peptide
β Scribed by M. A. Bednarek; B. E. Campbell; K. R. K. Easwaran; E. R. Blout
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1987
- Tongue
- English
- Weight
- 1004 KB
- Volume
- 26
- Category
- Article
- ISSN
- 0006-3525
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β¦ Synopsis
The ion binding characteristics of two bicyclic peptides, cyclo(Lys-Pro-Gly-Pro-Gly-Glu-Pro-Gly-Pro-G1y)-cyclo(1c + 6 y ) Gly (BCP7) and cyclo(Lys-Pro-Gly-Pro-Gly-Glu-Pro-Gly-Pro-G1y)qclo(lr + 6 y ) Gly-Gly (BCP8) in a lipophilic solvent, acetonitrile, have been studied using CD and nmr spectroscopy. The data indicate that both BCP7 and BCPB preferentially bind divalent ions. The nmr data showed that the conformation of both peptides in the free state was an average of many rapidly interconverting conformational states. The nmr titration data for Ca+2 ions with BCP7 and BCPB indicated that both of these bicyclic peptides bind to calcium ions forming stable 1 : 1 and possibly 1 : 2 Ca+' : BCP-type complexes. The conformation of the Ca+2 : BCP7 and Ca+2 : BCPB complexes were similar, with each containing two type I 8-turns, one cis X-Pro bond and three trans X-Pro bonds. In the 1 : 1 complex, the Ca+2 ion coordinates to four carbonyl oxygens from the face oppcsite the bridgehead peptide as well as to two carbonyl oxygens from the interior of the cavity.
π SIMILAR VOLUMES
The stereochemistry and conformation of a key bicyclic lactam-based Leu-Pro building block and the conformation of the surrounding peptide fragment were assigned using a combination of 2D-NOE data and coupling constants from an NMR simulation. The work conΓrmed that the initial stereochemistry of th
The conformational behavior of a heterodetic bicyclic decapeptide (BCPLT) in the absence and in the presence of calcium ions has been studied by means of mono and two-dimensional nmr techniques. Free BCPLT possessee a quite compact structure stabilized by intramolecular bonds and turns. In the struc