Crystalline peptides

Udupa, E.G.P., and Sharma, K.K. (2005) Effect of oxidized f B3-crystallin peptide on lens SL-crystallin interaction with l B2-crystallin. Invest. Ophthalmol. Vis. Sci. 46, 2514-2521. 

Properties of the Peptide Bond In x-ray studies of crystalline peptides, Linus Pauling and Robert Corey found that the C—N bond in the peptide link is intermediate in length (1.32 A) between a typical C—N single bond (1.49 A) and a C=N double bond (1.27 A). They also found that the peptide bond is planar (all four atoms attached to the C—N group are located in the same plane) and that the two a-carbon atoms attached to the C—N are always trans to each other (on opposite sides of the peptide bond). 

The observation of such suppressed peaks is not limited to membrane proteins as mentioned above but is also possible for a variety of fibrous proteins and crystalline peptides. In such cases, it is stressed that the l3C NMR signals of the Cp carbons, rather than the backbone Ca and carbonyl carbons, are in many instances suppressed, depending upon the manner of crystalline packing as encountered for collagen and enkephalins.94 I22 123... 

High resolution NMR has proved to be a very powerful approach to the analysis of solution conformations of peptides Q), The capability of obtaining high resolution NMR spectra of solid samples extends the opportunity for analysis to crystalline peptides (.2r3.) 1 therefore conparlsons can be made of peptide conformations in different environments and physical states. In addition, some of the information obtained from the analysis of solid-state NMR spectra is unique and provides insight into both static and dynamic aspects of peptide conformation. 

The peptide cvclo(Glv-Pro-GlvK presents a quite different situation. The analysis of its NMR spectrum leads to the conclusion that it adopts a Cp-symmetric conformation in solution, at least on NMR timescales. The solution NMR spectrum (Figure 2B) shows the minimum number of resonances expected (one per carbon in the repeating trlpeptlde unit). By contrast, in the solid-state spectrum there Is clear indication of asymmetry since there are two Pro Cg resonances in Figure 2A, X-ray diffraction analysis has revealed an asymmetric molecular conformation for the crystalline peptide (17), with two different types of 3-turns, only one of which is intramolecularly hydrogen-bonded. Analysis of the solid state isotropic chemical shifts in terms of local conformation yields a picture of the molecule which is consistent with the X-ray data,... 

X-ray studies of crystalline peptides by Linus Pauling and his colleagues determined the precise geometry of peptide bonds. The characteristic dimensions, which are common to all peptides and proteins, are shown in Figure 17.9. 

Arima K, Kahinuma A, Tamura G (1968) Surfactin, a crystalline peptide lipid surfactant produced by Bacillus subtilis isolation, characterization and its inhibition of fibrin clot formation. Biochem Biophys Res Commun... 

High-Resolution THz Spectroscopy of Crystalline Peptides Exploring Hydrogen-Bonding Networks... 

Karen Siegrist, Christine Bucher, Candace Pfefferkom, Andrew Schwarzkopf, and David Plusquellic apply high resolution THz spectroscopy to the investigation of the lowest frequency vibrational modes of crystalline peptides associated with the hydrogen-bonding networks of peptide crystals. 

Sato K, Itoh Y, Aida T (2011) Columnarly assembled liquid-crystalline peptidic macrocycles unidirectionally orientable over a large area by an electric field. J Am Chem Soc 133 (35) 13767-13769. doi 10.1021/ja203894r... 

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