Gc. Stratmann et al., BRAIN MEMBRANE SERINE-PROTEASE ACTIVITY IN HUMAN CORTEX COMPARED WITHRAT - IMPLICATION FOR ALZHEIMERS-DISEASE, Dementia, 5(2), 1994, pp. 62-68
Cerebral cortex from humans and rats was extracted sequentially with d
etergent-containing and low-ionic-strength buffers. The resulting pell
et was extracted with detergent/high-ionic-strength buffer to yield a
soluble enzyme preparation. This was incubated with substrate prepared
from rat cerebral cortical membranes containing amyloid precursor pro
tein-like immunoreactivity (APPLIR) of 116 kD approximate apparent mol
ecular mass. The effectiveness of various enzyme preparations to degra
de APPLIR was: routine-post-mortem (pm)-delay human samples > rat pup
> short-pm-delay human samples >> adult rat. In incubations with human
samples only a 100-kD product accumulated. The activity in human brai
n was inhibited by phenylmethylsulphonylfluoride, insensitive to Ca2+,
correlated with pyramidal neurone numbers but not those of astrocytes
and was not significantly higher in Alzheimer's disease compared with
controls. These data are discussed in terms of other approaches for s
tudying proteolytic activity to explain the deposition of beta-amyloid
protein in this disease.