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Conformation of cyclo(Gly-L-Pro-L-Pro-Gly-L-Pro-L-Pro)(2)Mg Complex Crystallized From CH(3)CN Solution

I L Karle, J Karle

Proc Natl Acad Sci U S A. 1981 Feb;78(2):681-5.

PMID: 16592971

Abstract:

The cyclic hexapeptides (Gly-L-Pro-L-Pro-Gly-L-Pro-L-Pro) in the (peptide-Mg-peptide)(2+) complex have nearly identical asymmetric conformations. Each has two cis Pro-Pro linkages and lacks any intraring hydrogen bonds. The Mg(2+) ion forms six ligands in a regular octahedral array with the carbonyl oxygen atoms of the two Gly residues and one Pro residue of each peptide. The "sandwich" complex has an approximate 2-fold rotation axis through the Mg(2+) relating the two peptide moieties. Cyclo(Gly-Pro-Pro-Gly-Pro-Pro)(2)Mg(ClO(4))(2). 4C(2)H(3)CN crystallizes in space group P3(1) with a = b = 15.744(4) A, c = 24.002(6) A, gamma = 120 degrees , and Z = 3. A highlight of the structure determination is the ready location of the Mg self-vector in a Harker section and the development of the entire structure by use of the tangent formula starting with the known position of the Mg atom.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
AP3705279 Cyclo-Gly-Pro Cyclo-Gly-Pro 3705-27-9 Price
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