Dipeptidyl aminopeptidase IV and aminopeptidase P, two proline specific enzymes from the cytoplasm of guinea-pig brain: their role in metabolism of peptides containing consecutive prolines
L. Gilmartin et G. O'Cuinn, Dipeptidyl aminopeptidase IV and aminopeptidase P, two proline specific enzymes from the cytoplasm of guinea-pig brain: their role in metabolism of peptides containing consecutive prolines, NEUROSCI RE, 34(1), 1999, pp. 1-11
In this study the majority of dipeptidyl aminopeptidase IV and aminopeptida
se P activities of guinea-pig brain are reported to reside in the cytoplasm
. Both activities were purified and soluble dipeptidyl aminopeptidase IV wa
s found to have a relative molecular mass of 194 000 and to be comprised of
two equal subunits of relative molecular mass 93 000 while native soluble
aminopeptidase P had a relative molecular mass of 140 000. Both activities
require proline or alanine in the penultimate position from the N-terminus.
Dipeptidyl aminopeptidase IV removed the N-terminal dipeptide whereas amin
opeptidase P removed only the N-terminal amino acid. Dipeptidyl aminopeptid
ase IV was inactive if proline was also present in the third position from
the N-terminus whereas aminopeptidase P was unable to remove the N-terminal
glycyl, pyroglutamyl or prolyl residues even though proline was present in
the second position. Soluble dipeptidyl aminopeptidase IV was differentiat
ed from the previously reported particulate form by its sensitivity to p-ch
loromercuribenzoate, N-ethyl maleimide and puromycin. The metabolism of Leu
-Pro Pro-Ser by guinea-pig cytoplasm was investigated in the presence of in
hibitors to evaluate the contribution by dipeptidyl aminopeptidase IV and a
minopeptidase P to the hydrolysis of a peptide containing two consecutive p
roline residues. The results indicated that either dipeptidyl aminopeptidas
e IV or prolyl oligopeptidase were required along with aminopeptidase P and
prolidase to achieve complete hydrolysis of this tetrapeptide. (C) 1999 El
sevier Science Ireland Ltd. All rights reserved.