Beta-pleated-sheet

Michael reactions and, 895 Beta-keto ester, 851 alkylation of, 859-860 cyclic, 892-893 decarboxylation of, 857, 860 Michael reactions and. 895 pKd of, 852 synthesis of, 892-893 Beta-lactam antibiotics, 824-825 Beta oxidation pathway, 1133-1137 mechanism of, 1133-1136 Beta-pleated sheet (protein), 1038 molecular model of, 1039 secondary protein structure and, 1038-1039 Betaine, 720 Bextra. structure of, 544 BHA, synthesis of, 629 BHT, synthesis of. 629 Bicycloalkane. 129 Bijvoet. J. M., 299 Bimolecular, 363... 

The essential distinction between the approaches used to formulate and evaluate proteins, compared with conventional low molecular weight drugs, lies in the need to maintain several levels of protein structure and the unique chemical and physical properties that these higher-order structures convey. Proteins are condensation polymers of amino acids, joined by peptide bonds. The levels of protein architecture are typically described in terms of the four orders of structure [23,24] depicted in Fig. 2. The primary structure refers to the sequence of amino acids and the location of any disulfide bonds. Secondary structure is derived from the steric relations of amino acid residues that are close to one another. The alpha-helix and beta-pleated sheet are examples of periodic secondary structure. Tertiary... 

Chemical treatment with formaldehyde may not necessarily result in significant denaturation. A recent study of RNase A indicated that treatment with formaldehyde does not significantly alter secondary structure.21,22 Although formalin treatment may induce subtle changes in secondary structure, alpha helices and beta-pleated sheets are left essentially intact after formalin treatment. It is reasonable to assume, however, that boiling (as per antigen retrieval protocols) will significantly alter secondary structure. 

Chothia, C. (1973). Conformation of twisted beta-pleated sheets in proteins./. Mol. Biol. 75, 295-302. 

Klunk, W. E., Pettegrew, J. W., and Abraham, D.J. (1989). Quantitative evaluation of Congo red binding to amyloid-like proteins with a beta-pleated sheet conformation. J. Histochem. Cytochem. 37, 1273-1281. 

Figure 4.2 This three-dimensional image of a protein shows the many twists and folds in its structure. The coils, called alpha helices, and the ribbons, called beta pleated sheets, are generally determined by the amino acid sequence of the protein and how the amino acids in different parts form weak bonds with each other. The shape of a protein is often critical for its function.

Secondary Structure of Proteins The secondary structure of a protein is how the polypeptide chain is twisted. There are two common types of secondary structure the alpha helix and the beta pleated sheet. 

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. 

Can a polypeptide chain fold into a regularly repeating structure In 1951, Linus Pauling and Robert Corey proposed two periodic structures called the a helix (alpha helix) and the p pleated sheet (beta pleated sheet). Subsequently, other structures such as the P turn and omega ( Q) loop were identified. Although not periodic, these common turn or loop structures are well defined and contribute with a helices and P sheets to form the final protein structure. 

Keywords Active vaccination Alzheimer s disease Amyloid Amyloid precursor protein Antibody titer Beta-pleated sheet Cerebral amyloid angiopathy Dementia Immunotherapy Monoclonal antibody Passive vaccination Senility... 

A. beta-pleated sheets with alternating hydrophilic and hydrophobic residues. 

Which of the following statements about beta-pleated sheets (b-sheets) is false ... 

A. a triple-stranded extended helix B. a beta-pleated sheet... 

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