Antiparallel 3 structures

Collagen-Model Peptides with Antiparallel Structure. 177... 

Figure 3.4 Packing of amides in unit cell (a) a-parallel structure of even-even PA (b) /3-antiparallel structure of even-even PAs with equal methylene sequence length in amine and acid unit, as in PA-4,620 (c) antiparallel PA-6-type polymer.

X can be any of the four nucleobases—G, A, C or U thus, four anticodons can be formed GGC, GAC, GCC and GUC. The antiparallel structure contains the codons GCC, GUC, GGC and GAC. Today, these codons code for the four amino acids alanine, glycine, valine and aspartic acid. These are, astonishingly, the four protein building blocks produced in the best yields in the Miller-Urey experiment, and they... 

Consider two Na 1 Cl ion pairs arranged in a "head to tail" or antiparallel structure in which the distance between ionic centers is 281 pm. Calculate the energy of this arrangement. 

Strand-turn-strand motifs in /1-solenoids differ fundamentally from those found in globular proteins. In globular structures, two adjacent strands with an intervening /l-turn form an antiparallel structure called a /1-hairpin (Fig. 10A). In /1-solenoids, the polypeptide chain also folds back on itself, but the flanking /1-strands make contact via their side chains rather than interacting via H-bonds of the backbone (Fig. 10A). As a result, consecutive strands find themselves in two different, parallel, /1-sheets. The latter strand-turn-strand structure is called a /1-arch, and its turn, a /1-arc (Hennetin et at., 2006 Yoder and Jurnak, 1995). In /1-solenoids, /1-arches stack in-register to form /1-arcades which have two parallel /1-sheets assembled from corresponding strands in successive layers. 

Oakley and Kim (1998) have described a simple and elegant experiment to switch the aforementioned Peptide Velcro from a parallel heterodimer to an antiparallel structure. The strategy was straightforward and resulted in a powerful design rule for specifying antiparallel structures. The Acid-pl... 

Chothia153 has observed that the (3 sheets in globular proteins have a right-handed twist. Computations on model 3 sheets, for example, the parallel and antiparallel structures of poly(L-valine) sheets,154 illustrated in Figure 18, have accounted for these observations.8 10 154 In general, side chain-backbone interactions within each strand result in a preference for a right-handed twist for L-amino acids, although there are exceptions. In addition, interstrand side... 

Figure 18 Stereo drawings of the minimum-energy p sheets with five CH,CO— (L-Val)6-NHCH3 chains. A. Antiparallel structure. B. Parallel structure.15,1...

FIGURE 12.36. Various types of protein tertiary structure, (a) An antiparallel a structure (cytochrome 6502) an up-and-down helix bundle (Ref. 113), (b) an antiparallel / structure (Cu,Zn superoxide dismutase) a Greek key (3 barrel (Ref. 114), and (c) and a parallel aj structure (triose phosphate isomerase) a singly wound parallel 0 barrel (Ref. 115). (Courtesy Jane S. Richardson)... 

Artificial cellulose showed the cellulose II allo-morph, a thermodynamically more stable form with an antiparallel structure, by X-ray diffraction study, when a crude celluase was employed for the enzymatic polymerization.123 The other allomorph cellulose I is a thermodynamically metastable form with a parallel structure, which living cells normally produce, but was believed impossible to be realized in vitro. Interestingly, however, the in vitro synthesis of cellulose I was successfully achieved by using a purified cellulase.125 The molecular packing of glucan chains in a crystal is affected by the purity of the enzyme as well as the enzymatic polymerization conditions. A novel concept choroselectivity was therefore proposed, which is concerned with the intermolecular relationship in packing of polymers having directionality in their chains.126... 

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