Poly-L-proline

Fig. 7. The far ultraviolet rotatory dispersions of poly-L-proline II and L-proline 0-0-0 in...

Arora, P.S., A.Z. Ansari, T. P. Best, M. Ptashne, and P. B. Dervan. Design of artificial transcriptional activators with rigid poly-L-proline linkers. J. Am. Chem. 

Fig. 8. (a) Sketch of the extended left-handed poly-L-proline II helical conforma-... 

The random coil amide I VCD pattern is exacdy the same shape, but smaller in amplitude and shifted in frequency from the pattern characteristic of poly-L-proline II (PLP II) which is a left-handed 3ihelix of trans peptides (Kobrinskaya et al., 1988 Dukor and Keiderling, 1991 Dukor et al., 1991 Dukor and Keiderling, 1996 Keiderling et al., 1999b). This... 

The Pn conformation of poly-L-proline (PP) or collagen in the solid state could be identified from X-ray fiber diffraction results (Cowan and McGavin, 1955). Persistence of this basic structure in solution was inferred from the resemblance between the CD spectra of solutions and films of the polypeptide. The CD spectra of the charged forms of PGA and PL closely resemble that of Pn (compare Fig. IB, 1C, and ID) however, these spectra differ significantly from those of PP peptides at high temperature or in the presence of high concentration of salts... 

M 0004. (From Tiffany and Krimm, 1969, Biopolymers 8, 347-359, 1969. Reprinted by permission of John Wiley Sons, Inc.) (B) CD spectrum of poly-L-proline II (sigma, molecular weight 55,000) as a function of temperature. (C) CD spectrum of polyglutamic acid at pH 7 as a function of temperature. (D) CD spectrum of poly-L-lysine at pH 7 as a function of temperature. Parts (B-D) are from Tiffany and Krimm (1972). Biopolymers 11, 2309-2316, 1972. Reprinted by permission of John Wiley 8c Sons, Inc. 

The validity of the Forster theory was tested and confirmed in a number of model studies with compounds that contained a donor and an acceptor separated by well-defined rigid spacers. This work has been reviewed 5] In a classical study, a naphthyl group (donor) was attached to the C-terminal and a dansyl group (acceptor) to the N-terminal of poly-L-proline oligomers (1-12 proline residues) 61 These proline oligomers assume a trans helical conformation in ethanol and thus represent spacers of well-defined length (12-46 A). A continuous decrease in the transfer efficiency from 100% at a donor-acceptor separation of... 

N 032 "Conformational Properties of Poly(L-proline) Form II in Dilute Solution"... 

The intrinsic viscosity of poly(L-proline) is studied as a function of molecular weight and temperature In five commonly used solvents water, trifluoroethanol, acetic acid, propionic acid, and benzyl alcohol. The characteristic ratio is 14 in water and 18-20 in the organic solvents at 303 K, and d (in 0) / d T is negative. The theoretical rotational potential function obtained by Hopfinger and Walton for u-prolyl-L-prolyl-t-prolyl-t-proline J. Macromol. Scl. Phys. 1969, 3, 171 correctly predicts the characteristic ratio at 303 K but predicts the wrong sign for tfiln < >0) IdT. 

N 054 "Calculation of the Characteristic Ratio of Randomly Coiled Poly(L-proline)"... 

Allowing for rotation about the Ca—C bond (/.e., variation of ijr) and for some degree of freedom about the peptide bond [i.e., small variation of ro), the characteristic ratios of the form / (crs) and form II [trans) poly(L-proline) chain are calculated by a Monte Carlo method in which the conformational energies are used as weighting factors. The Monte Carlo method enabled short-range interactions (beyond those involved in a single residue) to be taken into account. 

RIS theory, in the form appropriate for branched molecules, is used to calculate the mean-square unperturbed radius of gyration, < s2>0, for cross-linked polyglycine, poly(L-alanine),poly(L-proline),poly(i-alanyl-D-alanine),poly(i.-prolyl-L-pro lylglycine),poly(L-prolyl-i.-alanylglycine ,poly(glycyl-L-alanyl-L-pro line), andpoly(L-aianyl-L-alanylgIycine).Thecentral amino acid residue in each polypeptide chain is replaced by the L-cysteinyl residue involved in cross-link formation. Each cross-linked molecule is considered to contain two trifunctional branch points, the a-carbon atoms of the two... 

N 083 "Local Configuration of Poly(L-proline) in Dilute Solution ... 

With heating from 5 to 45°C, thermal changes in conformation in the major /3-casein are observed by spectral methods (Garnier 1966). From measurements of the optical density at 286 nm and of the specific optical rotation at 436 nm, a rapidly reversible endothermic transition (AH 30 kcal/mole) with a half-transition temperature of 23-24°C is observed. The optical rotatory dispersion data suggest a decrease in the poly-L-proline II structure (12 to 5%) and a slight increase in a-helix (11 to 16%) with increasing temperature. This transition probably occurs prior to association, since it is rapid, and the carboxyacyl derivative of the monomer, which does not polymerize with increasing temperature, also demonstrates the optical rotatory disperson thermal transition. 

Blout u. Mitarb. (172, 174) berichteten iiber die Synthese sowie die Konformation von Poly-L-prolin, das als Modell fur Kollagen von Interesse ist. 

The synthetic polyamino acids are convenient models for chemical studies of proteins since they have the extended polypeptide structure of the proteins but are free from the complications which arise in the proteins from the large number of different side chains. The work described here has been confined to the water-soluble polyamino acids poly-D,L-alanine (PDLA), poly-a,L-glutamic acid (PGA), poly-a,D-glutamic acid, and poly-a,L-lysine, and the polyimino acid, poly-L-proline. 

The yield of amide-like nitrogen in PGA was increased from G = 0.61 to G = 2.3, in PDLA from G = 0.66 to G = 2.0, and in poly-L-proline from G = 0.14 to G = 0.25. This effect of O2 is similar to that observed for the release of free NH3 from the amino acids, though the increase for PGA and PDLA is greater than for the amino acids (23). The value for PGA in O2 agrees closely with that reported by Sokol et at. (35). 

Automatic amino acid analysis of polyamino acids irradiated in 0.1% oxygen-free aqueous solution showed that for PGA, PDLA, and poly-L-proline, amino acid destruction increased linearly with dose up to 1 Mrad. The 6-values from these analyses were G(-Glu) = 0.85, G(-Ala) = 1.9, G(-Pro) = 1.8. 

Friedberg and Hayden (15) reported that glutamic acid was formed when poly-L-proline was irradiated in dilute aqueous solution in the absence of 02. We also found glutamic acid formation (G = 0.14) under similar conditions and confirmed the identity of the glutamic acid by two-dimensional thin-layer chromatography. A possible intermediate in this reaction... 

Glutamic acid was not formed when proline was irradiated under conditions similar to those described for poly-L-proline. 

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