Poly proline

Figure 8 CD and Absorption Spectra of Poly(Proline) in TFE[1451a...

This rather rigid poly-proline loop, together with the loop comprised of residues 241-250, lies on either side of the active site flap formed by residues 72-81. Hence, in the renins, the cleft is covered by the flaps from both lobes rather than from the N-lobe alone as in other pepsin-like aspartic proteinases. This gives renin a superficial similarity to the dimeric, retroviral proteinases where each subunit provides an equivalent flap that closes down on top of the inhibitor [44,45]. 

Polypeptides undergo a conformational change from helix to random coil when the solvent composition, pH or temperature is varied. Adsorption of polypeptides such as poly(/3-benzyl-L-glutamate), poly-proline, and polyhydroxyproline on glass was studied... 

Poly Proline Helices. Poly proline (PP) displays some unusual structural properties as it is die only naturally occuring tertiary amide found in polypeptides. The inability of this residue to act as a hydrogen-bond donor leads to two types of extended helical structures, neither of which resembles the a helix. The first, called PP I, is a right-handed helix which possesses cis amide bonds (left-handed helix with trans amide bonds ( d = 180°). Both occupy a fairly limited region of < >,y space. The two forms interconvert slowly over time. 

Fig. 11. Ribbon diagram of the GFCC /1-sheet face in Dl. The tt cation stacking motif and structural differences observed in the edge /3-strand are shown. /3-bulges (B1 or B2) and the left handed poly proline helix (PPII) in GHR D2 are denoted with arrows. Residues at the end of the /3-strand GDI that participated in cytokine contacts are labeled on the figure. IFNAR2 Gys-12 which forms a disulfide bond with cysteine on /3-strand is also labeled.

Low-complexity sequence. The phrase low-complexity sequence refers to stretches of nucleotide or protein sequence that are repetitive or simple in composition (11). Extreme examples include runs of As in a nucleotide sequence such as the poly-A tails of eukaryotic mRNAs, or the poly-proline tracts found in some... 

Rubert, M. Monjo, M. Lyngstadaas, S.P. Ramis, J.M. Effect of alginate hydrogel containing poly-proline-rich peptides on osteoblast differentiation. Biomed. Mater. October 2012, 7 (5), 055003. http // www.ncbi.nlm.nih.gov/pubmed/22782012. 

The different conformations can be distinguished from each other by the symbols A and B. A and B can, for example, be trans or gauche conformations or even the cis and trans positions of the peptide groups in poly(proline), etc. The process... 

Figure 1.4. Chiral supramolecular structures (a) a-helix of polypeptides, (b) poly-prolin-helix of collagene, and (c) deoxyribonucleic acid (DNA) Z = D-Deoxyribose, P = phosphoric acid, A — adenine, G = guanine, C = cytosine, T = thymine (from [8]).

Fully extended chain p parallel structure p antiparallel structure Polyproline I (oj = 0") Poly proline II (w = ISO ) Polyglycine II Collagen... 

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