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Antiparallel 3-sheets

Figure 2.5 Schematic illustrations of antiparallel (3 sheets. Beta sheets are the second major element of secondary structure in proteins. The (3 strands are either all antiparallel as in this figure or all parallel or mixed as illustrated in following figures, (a) The extended conformation of a (3 strand. Side chains are shown as purple circles. The orientation of the (3 strand is at right angles to those of (b) and (c). A p strand is schematically illustrated as an arrow, from N to C terminus, (bj Schematic illustration of the hydrogen bond pattern in an antiparallel p sheet. Main-chain NH and O atoms within a p sheet are hydrogen bonded to each other. Figure 2.5 Schematic illustrations of antiparallel (3 sheets. Beta sheets are the second major element of secondary structure in proteins. The (3 strands are either all antiparallel as in this figure or all parallel or mixed as illustrated in following figures, (a) The extended conformation of a (3 strand. Side chains are shown as purple circles. The orientation of the (3 strand is at right angles to those of (b) and (c). A p strand is schematically illustrated as an arrow, from N to C terminus, (bj Schematic illustration of the hydrogen bond pattern in an antiparallel p sheet. Main-chain NH and O atoms within a p sheet are hydrogen bonded to each other.
Figure 2.11 Beta sheets are usuaiiy represented simply by arrows in topology diagrams that show both the direction of each (3 strand and the way the strands are connected to each other along the polypeptide chain. Such topology diagrams are here compared with more elaborate schematic diagrams for different types of (3 sheets, (a) Four strands. Antiparallel (3 sheet in one domain of the enzyme aspartate transcarbamoylase. The structure of this enzyme has been determined to 2.8 A resolution in the laboratory of William Lipscomb, Harvard University, (b) Five strands. Parallel (3 sheet in the redox protein flavodoxin, the structure of which has been determined to 1.8 A resolution in the laboratory of Martha Ludwig, University of Michigan, (c) Eight strands. Antiparallel barrel in the electron carrier plastocyanln. This Is a closed barrel where the sheet is folded such that (3 strands 2 and 8 are adjacent. The structure has been determined to 1.6 A resolution in the laboratory of Hans Freeman in Sydney, Australia. (Adapted from J. Richardson.)... Figure 2.11 Beta sheets are usuaiiy represented simply by arrows in topology diagrams that show both the direction of each (3 strand and the way the strands are connected to each other along the polypeptide chain. Such topology diagrams are here compared with more elaborate schematic diagrams for different types of (3 sheets, (a) Four strands. Antiparallel (3 sheet in one domain of the enzyme aspartate transcarbamoylase. The structure of this enzyme has been determined to 2.8 A resolution in the laboratory of William Lipscomb, Harvard University, (b) Five strands. Parallel (3 sheet in the redox protein flavodoxin, the structure of which has been determined to 1.8 A resolution in the laboratory of Martha Ludwig, University of Michigan, (c) Eight strands. Antiparallel barrel in the electron carrier plastocyanln. This Is a closed barrel where the sheet is folded such that (3 strands 2 and 8 are adjacent. The structure has been determined to 1.6 A resolution in the laboratory of Hans Freeman in Sydney, Australia. (Adapted from J. Richardson.)...
FIGURE 6.10 A pleated sheet of paper with an antiparallel /3-sheet drawn on it. [Pg.168]

Parallel /3-sheets tend to be more regular than antiparallel /3-sheets. The range of (f) and i/t angles for the peptide bonds in parallel sheets is much smaller than that for antiparallel sheets. Parallel sheets are typically large structures those composed of less than five strands are rare. Antiparallel sheets, however, may consist of as few as two strands. Parallel sheets characteristically distribute... [Pg.169]

In addition to classification based on layer structure, proteins can be grouped according to the type and arrangement of secondary structure. There are four such broad groups antiparallel a-helix, parallel or mixed /3-sheet, antiparallel /3-sheet, and the small metal- and disulfide-rich proteins. [Pg.184]

Proteins containing a large amount of antiparallel /3-sheet usually show negative ROA bands in the range 1340—1380 cm-1, especially if the /3-sheet is extended as in a sandwich or barrel, which appear to originate in tight turns of the type found in /3-hairpins. One example is the band at 1345 cm-1 in jack bean concanavalin A (Fig. 4). These bands do not appear in the ROA spectra of a/// proteins, since these contain only parallel /6-sheet with the ends of the parallel /6-strands connected by a-helical sequences rather than tight turns (Barron etal., 2000). [Pg.89]

Fig. 20. An example of antiparallel /3 sheet, from Cu,Zn superoxide dismutase (residues 93-98,28-33, and 16-21). Arrows show the direction of the chain on each strand. Main chain bonds are shown solid and hydrogen bonds are dotted. In the pattern characteristic of antiparallel /8 sheet, pairs of closely spaced hydrogen bonds alternate with widely spaced ones. The direction of view is from the solvent, so drat side chains pointing up are predominantly hydrophilic and those pointing down are predominantly hydrophobic. Fig. 20. An example of antiparallel /3 sheet, from Cu,Zn superoxide dismutase (residues 93-98,28-33, and 16-21). Arrows show the direction of the chain on each strand. Main chain bonds are shown solid and hydrogen bonds are dotted. In the pattern characteristic of antiparallel /8 sheet, pairs of closely spaced hydrogen bonds alternate with widely spaced ones. The direction of view is from the solvent, so drat side chains pointing up are predominantly hydrophilic and those pointing down are predominantly hydrophobic.
There is a correlation between the backbone conformations which commonly flank disulfides and the frequency with which disulfides occur in the different types of overall protein structure (see Section III,A for explanation of structure types), although it is unclear which preference is the cause and which the effect. There are very few disulfides in the antiparallel helical bundle proteins and none in proteins based on pure parallel /3 sheet (except for active-site disulfides such as in glutathione reductase). Antiparallel /3 sheet, mixed /8 sheet, and the miscellaneous a proteins have a half-cystine content of 0-5%. Small proteins with low secondary-structure content often have up to 15-20% half-cystine. Figure 52 shows the structure of insulin, one of the small proteins in which disulfides appear to play a major role in the organization and stability of the overall structure. [Pg.231]

Partial, multiple, and other barrels have been grouped together as another subgroup within the antiparallel /3 category (see Fig. 82). Ri-bonuclease contains a four-stranded antiparallel /3 sheet that looks like a five-stranded barrel with one strand missing. Alcohol dehydrogenase dl includes a five-stranded antiparallel barrel (with a topology of +1, +3x, —2, +1) and another partial five-stranded barrel. [Pg.304]

Fig. 102. Glyceraldehyde-phosphate dehydrogenase domain 2 as an example of an open-face sandwich antiparallel /3 sheet, (a) a-Carbon stereo, viewed from the buried side of the sheet (b) backbone schematic, viewed as in a. Fig. 102. Glyceraldehyde-phosphate dehydrogenase domain 2 as an example of an open-face sandwich antiparallel /3 sheet, (a) a-Carbon stereo, viewed from the buried side of the sheet (b) backbone schematic, viewed as in a.
The three-dimensional structural architecture of plant defensins is exemplified by the structure of Rs-AFP, ° which comprises an N-terminal /3-strand followed by an ct-helix and two /3-strands (/3a/3/3 configuration). The /3-strands form a triple-stranded antiparallel /3-sheet. The three-dimensional structure is stabilized by three disulfide bonds. In general, in plant defensins two disulfide bonds form between the ct-helix and the central /3-strand. A third disulfide bond stabilizes the structure by linking the /3-strand after the helix to the coiled part after the ct-helix. This motif is called the cysteine-stabilized a/3-motif (CSa/3)" and also occurs in toxins isolated from insects, spiders, and scorpions.The fourth disulfide bond links the C-terminal end of the peptide with the N-terminal /3-strand. Two plant defensins, PhDl and PhD2, feature a fifth disulfide bond and have been proposed to be the prototypes of a new subclass within plant defensins." As a result of these structural features the global structure of plant defensins is notably different from o //3-thionins, which is one of the reasons for the different nomenclature. The structures of plant defensins Rs-AFP ° and NaDf are shown in Figure 6, where they are compared to the thionin /3-purothionin and the structurally more related drosomycin and charybdotoxin. ... [Pg.263]

The C-terminal domain is built around an a[3-io A including the three class-defining motifs. It contains the catalytic site formed by a six-stranded antiparallel /3-sheet including motifs 2 and 3 and by a dimer interface, which includes motif 1. This /3-sheet is interrupted between motifs 2 and 3 by a module formed by four helices and a /3-strand. [Pg.398]

Type i and ii membrane proteins only contain one transmembrane helix of this type, while type ill proteins contain several. Rarely, type i and ii polypeptides can aggregate to form a type iV transmembrane protein. Several groups of integral membrane proteins—e.g., the porins (see p. 212)—penetrate the membrane with antiparallel (3-sheet structures. Due to its shape, this tertiary structure is known as a P-barrel. ... [Pg.214]

The structure of PaFd was the first to be crystallographically determined (Adman et ai, 1973). The basic fold of the protein may be described as a pair of two stranded antiparallel )3 sheets. The two 4Fe 4S clusters are sandwiched between these /3 strands on one side and several helical segments on the other side. The clusters are packed in a predominantly hydrophobic environment. The internal sequence homology is clearly reflected in the structure the two clusters and much of the polypeptide chain are related by an approximate internal twofold rotation axis. The two clusters are ligated by the two sets of four cysteines in the two halves of the molecule. Surprisingly, each cluster is liganded by cysteines from both halves of the sequence, rather than cysteines from only one half (which are adjacent in the sequence). Cluster 1 is coordinated by Cys-8, -11, and -14 in the amino-terminal half and Cys-45 of the carboxy-terminal half, while cluster 2 is coordinated by Cys-35, -38, and -41 of the carboxy-terminal half and Cys-18 of the amino-terminal half. [Pg.253]

Many scorpion toxins, insect defensins, and enzyme inhibitors are cystine-rich polypeptides containing three to four disulfide bonds. In a large number of these toxins, two cystines are involved in the consensus Cys-(Xaa)1-Cys/Cys-(Xaa)3-Cys framework which is responsible for the common characteristic fold consisting of an a-helix and a two- or three-stranded antiparallel (3-sheet (a 3 3-fold or 3a 3 3-fold). For a review see ref[69]. The overall compact globular structures of these cystine-rich peptides contain the cystine stabilized a-helix motif (Section 6.1.5.1.2) which is further stabilized by a third disulfide bond between the N-terminus and the (3-strand adjacent to the helix and in some cases by an additional fourth disulfide bridge. Due to the presence of the cystine stabilized a-helix motif, a preferred initial formation of this motif followed by its stabilization via the additional disulfides was expected. However, in contrast to what was observed for the cystine peptides containing only the cystine stabilized a-helix motif, simple air oxidation is not successful. [Pg.148]


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See also in sourсe #XX -- [ Pg.32 , Pg.33 ]




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Antiparallel

Antiparallel 3-Sheet Based Nanofibers

Antiparallel P sheets

Antiparallel beta sheets

Antiparallel beta-pleated sheet

Antiparallel p-pleated sheets

Antiparallel pleated sheet

Antiparallel-chain pleated sheet structures

Beta pleated sheet parallel, antiparallel

Conformations antiparallel-chain pleated sheet

Extended structures antiparallel-chain pleated sheet

Peptides antiparallel /?-sheet

Polypeptides antiparallel pleated-sheet structure

Sheet structures antiparallel’ mode

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