N. Fujii et al., THE CONFORMATION FORMED BY THE DOMAIN AFTER ALANINE-155 INDUCES INVERSION OF ASPARTIC ACID-151 IN ALPHA-A-CRYSTALLIN FROM AGED HUMAN LENSES, Biochemical and biophysical research communications, 239(3), 1997, pp. 918-923
A new cleavage site, which is a post-translational modification, was f
ound between residues His-154 and Ala-155 in alpha A-crystallin hom th
e aged human lens. After trypsin digestion of alpha A-crystallin two p
eptides that include Asp-151 were obtained and have remarkable differe
nces. That is, the stereo-configuration of the Asp-151 in the normal l
ength peptide was predominately inverted to the D-isomer of beta-aspar
tyl form (D/L of 5.7), However, the stereoconfiguration of the Asp-151
in the cleavage peptide, that lacks the sequence following Ala-155 to
the C-terminus, remained predominately in the L-isomer form as indica
ted by a D/L value of 0.3. The results suggest that the secondary stru
cture in the region of Ala-155 to the C-terminus may constitute a held
that causes the inversion of the Asp-151 to the D-isomer form, Since
this kind of cleavage was not found in alpha A-crystallin from young l
ens, the cleavage between His-154 and Ala-155 is probably the result o
f aging. (C) 1997 Academic Press.