Beta sheet, structure

Li L, Darden TA, Bartolotti L, Kominos D, Pederson LG. An atomic model for the pleated beta-sheet structure of Abeta amyloid protofilaments. Biophys J 1999 76 2871-2878. 

Nesloney, C. L., and Kelly, J. W. (1996). Progress towards understanding [beta]-sheet structure. Bioorg. Med. Chem. 4, 739-766. 

Balbirnie, M., Grothe, R., and Eisenberg, D. S. (2001). An amyloid-forming peptide from the yeast prion Sup35 reveals a dehydrated beta-sheet structure for amyloid. Proc. 

Gordon, D. J., Balbach, J. J., Tycko, R., and Meredith, S. C. (2004). Increasing the amphiphilicity of an amyloidogenic peptide changes the beta-sheet structure in the fibrils from antiparallel to parallel. Biophys. J. 86, 428-434. 

Serpell, L. C., and Smith, J. M. (2000). Direct visualisation of the beta-sheet structure of synthetic Alzheimer s amyloid./. Mol. Biol. 299, 225-231. 

There is a wide variety of so-called globular proteins. Many of these have alpha and beta structures imbedded within the overall globular structure. Beta sheets are often twisted or wrapped into a barrel-like structure. They contain portions that are beta sheet structures... 

Koch et al. [111] have discussed the use of graph theoretical techniques in an attempt to find rules to relate beta sheet topology to amino acid sequence and for the comparison of beta sheet structures. They defined a graph representation for every protein in the PDB that contains beta sheets, notations and graphic representations for sheets which described the sequential and topological neighbourhoods of the strands, and constructed tools for substructure searches of this database. 

The beta pleated sheet, or simply beta sheet, structure is illustrated in Figure 12.53. The carbon backbone in the beta sheet is fully extended, and adjacent chains are held together by a large number of hydrogen bonds. 

Yamada, N., Ariga, K., Naito, M., Matsubara, K., and Koyama, E. "Regulation of beta-sheet structures within amyloid-like beta-sheet assemblage from tripeptide derivatives".. Am. Chem. Soc. 120(47), 12192-12199 (1998). 

Two methods have been used to determine the secondary structure and orientation of membrane proteins in supported bilayers polarized ATR-FTIR spectroscopy and oriented CD spectroscopy. SFVS may also be applied to study peptide and protein structures in supported bilayers. Polarized ATR-FTIR spectroscopy is sensitive enough that high-quality spectra can be obtained from a single bilayer. Beta-sheet structures are readily distinguished from a-helical and random stmctures, and the orientations of a-helices are determined from the linear dichroism of the peptide amide 1 bands (20). Multiple stacks of supported bilayers have to be used to gain enough sensitivity to determine the stmcture and orientation of a-helices in lipid bilayers by oriented CD spectroscopy (60, 93). 

This group of diseases is characterized by the accumulation of a specific isoform of the normal prion protein (PrP), termed PrPSc, which seems to be the main infectious agent. PrPSc is derived by a conformational change from the isoform of the prion protein PrPC. PrPSc is a copper-binding glycoprotein attached to the cell membrane of neuronal cells [21]. The PrPSc form is protease resistant, has a beta-sheet structure and possesses a tendency to polymerization [22]. 

The crystal structure of the active site of PARP has been described (5).It is made up of a five-stranded antiparallel beta sheet and a four-stranded mixed beta sheet (Fig. 11.2). The two beta sheets are connected by two hydrogen bonds. The beta sheet structure is supported by a surrounding protein structure made up of five alpha helices, three 3iq helices, and beta sheet excursions. The active site is... 

Shewmaker F, McGlinchey RP, Thurber KR et al (2009) The functional curli amyloid is not based on in-register parallel beta-sheet structure. J Biol Chem 284 25065-25076... 

Shewmaker F, Kryndushkin D, Chen B, Tycko R, Wickner RB (2009) Two prion variants of Sup35p have in-register parallel beta-sheet structures, independent of hydration. Biochemistry 48 5074-5082... 

Shewmaker F, Ross E, Tycko R, Wickner R (2006) Amyloids of shuffled prion domains that form prions have a parallel in-register beta-sheet structure. Biochemistry 47 4000-4007... 

Shewmaker F, Wickner R, Tycko R (2008) Amyloid of the prion domain of Sup35p has an in-register parallel beta-sheet structure. Proc Natl Acad Sci USA 103 19754—19759... 

Ala, Ser, and Gly could work in a beta sheet structure because of their small or nonexistent side chains which could allow the stacking of beta chains. 

The linear peptide as observed in its primary structure starts folding on itself because of the interactions among the side chains of the adjacent amino acids. This leads to the formation of different structures, which include (a) helical structure called an alpha helix, (b) stranded folds called beta sheets or beta strands, and (c) random coils. Now, certain criteria can be used to predict the occurrence of these structures in the secondary structure of the protein. This was first established by Chow and Fasman (1978) based on the propensity of certain amino acids associated with these structures, i.e., helix and beta sheet. For example, the amino acids glu, met, ala, and lys are predominantly associated with the helix structure whereas the amino acids val, ile, and tyr are strongly associated with the beta sheet structure. The amino acid leucine is associated with both the helix and the beta sheet. The amino acids glycine and proline occur as breakers of the helix proline usually occurs as the first residue in the helix. Also, asp and glu occurs at the N-terminus, whereas arg and lys occur at the C-terminus. 

Post, K., Pitschke, M., Schafer, O., Wille, H., Appel, T.R., Kirsch, D., Mehlhorn, 1., Serban, H., Prusiner, S.B., and Riesner, D. (1998). Rapid acquisition of beta -sheet structure in the prion protein prior to multimer formation. BioL Chem. Biol. Chem. 379, 1307-1317. 

Defensins are variably cationic, relatively arginine-rich, nonglycosylated peptides comprised of 29-34 amino acid residues. Human (HNP-1) and rabbit (NP-5) defensins have been studied by NMR techniques and showed that they are rich in beta sheet structure. Although both types of defensins permeabilize the outer membrane of E. coli [31], they differ from other peptides with similar action but rich in alpha helices such as magainin, mellitin and cecropin. 

The protein conformation in films was characterised by infra red measurements. Spectra obtained by attoiuated total reflectitm and data in the amide I region were compared in order to characterise the secondary structure of proteins in the film. The dectmvolved spectra, as shown here, presented two main bands at 16S0 and 1621 cm (Fig 5). The band at 1650 is generally assigned to the helical conformation and the 1621 cm bands reflects the presence of intermolecular hydrogen bonded beta sheet structure. The spectra recorded for gluten in film state are comparable to those... 

The cast SELP-47K films are not mechanically stable after hydration [65, 67] and it is therefore necessary to stabilize its structure. Methanol induces the crystallization of the silklike blocks, leading to aqueous insolubility, and improves the mechanical properties by the conversion of less-ordered conformations into more ordered anti-parallel beta-sheet structures [87,88]. Under uniaxial tensile stress-strain, fully hydrated treated films exhibited an ultimate... 

Indicate whether each statement is true or false, (a) The sequence of amino acids in a protein, from the amine end to the acid end, is called the primary structure of the protein, (b) Alpha helix and beta sheet structures are examples of quaternary protein structure, (c) It is impossible for more than one protein to bind to another and make a higher order structure. 

Indicate whether each statement is true or false (a) In the alpha helical structure of proteins, hydrogen bonding occurs between the side chains (R groups), (b) Dispersion forces, not hydrogen bonding, holds beta sheet structures together. 

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