Circular dichroism fragment-spectra

Fig. 5.—Circular Dichroism Fragment-Spectra (from Top to Bottom) Addition of a Hydroxymethyl Group at C-5, with the OH-4 Group Equatorial, Average for Five Pairs of Aldoses 4-Hydroxyl Group Equatorial to Axial, One Pair of Aldoses Addition of a Hydroxymethyl Group at C-5, with the 4-Hydroxyl Group Axial for a-o-Aldoses, Average for Two Pairs of Aldoses and Addition of a Hydroxymethyl Group at C-5, with the 4-Hydroxyl Group Axial for -D-AldoL s, Average for Two Pairs of Aldoses. (Redrawn from Ref. 6.)...

For structural studies of PrP, recombinant proteins were expressed in Escherichia coli. The constructs used contain either the intact polypeptide chain of the mature form of natural PrP (Fig. 1), possibly with some additional, construct-related residues at either chain end, or fragments thereof. Presently it appears impractical to envisage three-dimensional structure determinations with mammalian prion proteins from natural sources. However, sufficient amounts of natural PrP have been isolated to enable qualitative comparative studies with the recombinant protein by optical spectroscopy. Overall, these experiments indicate close similarity between the natural and the corresponding recombinant prion protein. Thus, the circular dichroism (CD) spectrum of monomeric hamster PrP extracted from hamster brains into a micellar environment of 30 mM w-octyl-P-glucopyranoside at pH 7.5 is typical for... 

Spectrum (- -), and Fragment Circular Dichroism Spectra (—) for the Corresponding d-Xylose and the Addition of a Hydroxymethyl Group at C-S (a) a-o-Glucose (b) /3-D-Glucose (c) Methyl a-o-Glucopyranoside and (d) Methyl /8-D-Glucopyranoside. (Redrawn from Ref. 

Measurements of circular dichroism, as well as ORD, are consistent with the presence of little a-helix (45-47). Cathou et al. interpreted a negative band at 217 nm in the circular dichroic spectrum of the Fab fragment of nonspecihc rabbit IgG or of rabbit antidinitrophenyl antibody as indicative of the presence of a substantial amount of /3 structure the band was more pronounced in the Fab fragment of the antibody than in the Fab fragment of IgG. An alternative possibility, that the band is due to aromatic structures, was considered less probable. As indicated above, there is a very substantial amount of /3-pleated sheet structure in each of the four domains of an Fab fragment or in the two domains of a dimer. This confirms the interpretation of data on circular dichroism favored by Cathou and co-workers. 

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