Fibroins: Difference between revisions
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Determine the sequence of the segment by hovering over the residues taking time to consider the nature of their side chains and from which direction their side chains project from the backbone. All the Gly need to be on the same side of the peptide in order to construct the silk fiber. Labels describe how additional <scene name='Fibroins/Chain_a_2/1'>units of the hexapeptide</scene> are added to the ends of this peptide segment to produce the longer polypeptide. | Determine the sequence of the segment by hovering over the residues taking time to consider the nature of their side chains and from which direction their side chains project from the backbone. All the Gly need to be on the same side of the peptide in order to construct the silk fiber. Labels describe how additional <scene name='Fibroins/Chain_a_2/1'>units of the hexapeptide</scene> are added to the ends of this peptide segment to produce the longer polypeptide. | ||
A two strand β-sheet is formed by <scene name='Fibroins/Chains_ab/2'>two hexapeptides</scene> positioned antiparallel with respect to each other. Show <scene name='Fibroins/Chains_ab_3/2'>hbonds</scene> which hold | A two strand β-sheet is formed by <scene name='Fibroins/Chains_ab/2'>two hexapeptides</scene> positioned antiparallel with respect to each other. Show interchain <scene name='Fibroins/Chains_ab_3/2'>hbonds</scene> which hold chains together. Show <scene name='Fibroins/Chains_ab_3/1'>spacefill</scene> display. | ||
Adding two more chains to form a <scene name='Fibroins/Four_strands/2'>four stranded beta-sheet</scene>. Show <scene name='Fibroins/Four_strands_2/1'>spacefill</scene> rendition. | |||
Two <scene name='Fibroins/Two_sheets/1'>stacked sheets</scene>. Show <scene name='Fibroins/Two_sheets_2/1'>hbonds</scene>. | Two <scene name='Fibroins/Two_sheets/1'>stacked sheets</scene>. The two sheets come together so that the 'Ala side chains' face each other with the methyl and hydroxymethyl groups intercalated. These sheets are attracted to each other and held in place by the hydrophobic forces generated between these side chains. Show interchain <scene name='Fibroins/Two_sheets_2/1'>hbonds</scene> within one sheet. <scene name='Fibroins/Two_sheets_3/1'>Spacefill display</scene> shows that the methyl side chains of the two sheets are close enough to produce hydrophobic forces. | ||
A <scene name='Fibroins/Three_sheets/1'>third sheet</scene> is stacked with the other two so that the Gly side chains (hydrogen atoms) intercalate. Show <scene name='Fibroins/Three_sheets_2/1'>interchain hbonds</scene> of all three sheets. This view shows that where the Gly side chains contact the backbonds of the sheets are much closer to each other. | |||
Revision as of 21:35, 1 September 2011
Fibroins are proteins that constitute silk fibers. Fibroins are large complex proteins and the specific structural details of those making up different types of silk are different, but all fibroins have some common characteristics. Interesting general information on spider silk and a model of one type of a spider silk molecule is at[1]. This model of spider silk shows two repeating domains that all fibroins contain. One domain is characterized as being amorphous, also called flexible, disordered segments, and the other one, symbolized by the boxes, has a highly ordered, repetitive, crystal-like structure. The objective of this exercise is to explicate this ordered domain of the protein.
Repetitive peptide segment & β-sheetDisplayed here is a peptide segment that is present in many fibroin proteins that are found in silk fibers. () It is repeated many times to make up the ordered, repetitive structure of the crystalline domain of the fibroin.
A two strand β-sheet is formed by positioned antiparallel with respect to each other. Show interchain which hold chains together. Show display. Adding two more chains to form a . Show rendition. Two . The two sheets come together so that the 'Ala side chains' face each other with the methyl and hydroxymethyl groups intercalated. These sheets are attracted to each other and held in place by the hydrophobic forces generated between these side chains. Show interchain within one sheet. shows that the methyl side chains of the two sheets are close enough to produce hydrophobic forces. A is stacked with the other two so that the Gly side chains (hydrogen atoms) intercalate. Show of all three sheets. This view shows that where the Gly side chains contact the backbonds of the sheets are much closer to each other.
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