Author:
Mendz GL,Moore WJ,Carnegie PR
Abstract
Myelin basic proteins from
human, cow, pig, rabbit and chicken central nervous systems were studied in
aqueous solution by proton n.m.r. at 400 MHz. Species comparisons and other
techniques led to the assignment of resonances of 23 specific amino acid residues
in the primary structure. Resonances from side chains of polar amino acids
adjacent to aspartic residues could be assigned by anomalous effects of pH on
the chemical shifts. The pK values of histidine side chains all fall in the range
6.0-6.9, and four specific histidine residues were assigned. The conformation
of the protein in aqueous solution is that of an extended non-random
polypeptide chain with regions of localized structure. Nuclear Overhauser difference spectra showed that a reverse turn
similar to that previously suggested for an encephalitogenic
nonapeptide isolated from the protein (guinea pig
determinant) occurs also in the protein itself, thus supporting the concept of
special low-energy conformations responsible for biological activity. Upfield chemical shifts of some side chain methyl groups
from the central region of the primary structure suggest ring-current shifts
due to higher-order structuring.
Cited by
45 articles.
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