1 Helices From Readily in Biological StructuresA helix is generated simply by placing many similar subunits next to each other each in the same way strictly related repeated relationship to the one b ID: 959748
Download Pdf The PPT/PDF document "The Helix and the Sheet Are Common Fol..." is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
1 The Helix and the Sheet Are Common Folding PatternsAlthough the overall conformation each protein is unique, there are only two different folding patterns are present in all proteins, which are helix sheet helix was first discovered in -keratin, which is abundant in skin and its derivative. sheet was found in protein fibroin, the major constituent of silk. These two fold
ing pattern are particularly common because they result from hydrogen bonds forming between the N-H and C=O groups in the polypeptide backbone. Because amino acids side chains are not involve in forming thesehydrogen bonds, helices and sheets can be generated by many different amino acids sequences. Helices From Readily in Biological StructuresA helix is generated simply by pla
cing many similar subunits next to each other, each in the same way strictly related repeated relationship to the one before. An helix is generated when a single polypeptide chain turns around itself to form structurally rigid cylinder. A hydrogen bonds is made between every forth peptide bond, linking the C=O of one peptide bond to the N-H of another. This gives rise to a re
gular helix with a complete turn every 3.6 amino acids Short region of helix are especially abundant in the proteins located in cell membranes, such as transport proteins and receptors 2 Sometimes a pair of helices will wrap around one another to form a particularly stable structure, known as a coiled-coil. This structure forms when two heliceshave most of their nonpolarside
chains on one side, so that they can twist around each other with these side chains facing inward Sheets Form Rigid Structures at the Core of Many Proteins sheets are made when hydrogen bonds form between segments of polypeptide chains lying side by side. When structure consists of neighboring polypeptide chains that run into same orientation, it is considered a parallel she
et; when it form apolypeptide chain that folds back and fourth upon itself-with each section of the chain running in the direction opposite to that of its immediate neighbors-the structure is an antiparallel sheet. Both types of B sheets produce very rigid, pleated structure, and they form the core of many proteins. When structure consists of neighboring polypeptide chains tha
t run into same orientation, it is considered a parallel sheet; when it form apolypeptide chain that folds back and fourth upon itself-with each section of the chain running in the direction opposite to that of its immediate neighbors-the structure is an antiparallel sheet. Both types of B sheets produce very rigid, pleated structure, and they form the core of many proteins.