Polyproline II helix

Each polytripeptide chain is twisted around a threefold screw axis and exists in a secondary structure, analogous to the left-handed polyproline II-helix, i.e. with transposition of the peptide bond (pitch 8.4 A, 3 amino acids) (Figs. 2,3). 

Three theory papers are also included. Determinants of the Polyproline II Helix from Modeling Studies by Creamer and Campbell reexamines and extends an earlier hypothesis about Pn and its determinants. Hydration Theory for Molecular Biophysics by Paulaitis and Pratt discusses the crucial role of water in both folded and unfolded proteins. Unfolded State of Peptides by Daura et al. focuses on the unfolded state of peptides studied primarily by molecular dynamics. 

DETERMINANTS OF THE POLYPROLINE II HELIX FROM MODELING STUDIES... 

The crystal structure of the peptide substrate-binding domain (140—245 of 517 residues of human al subunit) of the human type I enzyme forms 2.5 tetratricopeptide (TPR) repeat domains with five a helices (PDB accession number ITJC). The organization of tyrosine residues is suggested to be key to its interaction with the substrate peptide in a polyproline II helix. The TPR motif is composed of a 34 amino acid repeated a helical motif, and is typically involved in protein-protein interactions. The tandem repeats of TPR motifs are found in many proteins related to chaperone, cell cycle, transcription, and protein transport... 

Ma, K., and Wang, K. (2003). Malleable conformation of the elastic PEVK segment of titin Non-cooperative interconversion of polyproline II helix, beta-turn and unordered structures. Biochem.J. 374, 687-695. 

The collagen triple helix has a unique CD spectmm. The spectrum shows a positive peak at 220-225 nm, and a negative peak at 195-200 nm. In contrast, the polyproline II helix has a positive peak at 228 nm, and a negative peak at 206 nm. The polyproline II like poly-4-hydroxyproIine helix has a positive peak at 219 nm and a negative peak at 205 nm (13). The thermal stability of the triple helix can be monitored easily by the CD... 

Blanch, E.W., Morozova-Roche, L.A., Cochran, D.A., Doig, A.J., Hecht, L., and Barron, L.D. Is polyproline II helix the killer conformation A Raman optical activity study of the amyloidogenic prefibrillar intermediate of human lysozyme, /. Mol. Biol., 301, 553, 2000. 

Kelly, M.A., Chellgren, B.W., Rucker, A.L., and Troutman, J.M., Fried, M.G. Host-guest study of left-handed polyproline II helix formation. Biochemistry, 40, 14376, 2001. 

Kentsis, A., Mezei, M., Gindin, T., and Osman, R. Unfolded state of polyalanine is a segmented polyproline II helix, Prot. Struct. Funct. Biol, 55, 493, 2004. 

Rucker, A.L., Pager C.T., Campbell, M.N., Qualls, J.E., and Creamer, T.P. Host-guest scale of left handed polyproline II helix formation. Protein. Struct. Funct. Genet., 53, 68, 2003. 

Creamer, T. P. (1998). Left-handed polyproline II helix formation is (very) locally driven. Proteins 33, 218-226. 

X-ray crystallographic analyses of the ferrocenes 29 and 30b-d bearing only one oUgoprolyl chain reveal that these ferrocenes adopt a left-handed polyproline II helix with all prohnes in a mutually fraws-conformation [81]. 

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