Biomedical Engineering Reference
In-Depth Information
essentially no activity for the Swedish mutant b-secretase substrate (Table 6.1).
The distinct preference of cathepsin B for the WT b-secretase site is indicated
by its high catalytic eciency represented by its k
cat
/K
m
value of 3.17
10
5
M
-1
s
-1
,
40,42
indicating an active enzyme.
Analyses with longer peptide substrates also show that cathepsin B cleaves
the WT b-secretase site.
15,43
The endogenous cathepsin B purified from Ab-
containing secretory vesicles cleaves the WT b-secretase site of the peptide
substrate
SVK
k
MDAEF (the
site).
15
arrow shows
the
b-secretase
(a)
(b)
30
1 2
25
20
15
10
DCG-04
:
+ +
CA074
:
- +
5
0
Control
E64c
CA074
(c)
Cathepsin B
MWRLLATLSC LLVLTSARSS LYFPPLSDEL VNFVNKQNTT WKAGHNFYNV DLSYVKKLCG
1
AILGGPKLPQ RDAFAADVVL PESFDAREQW PNCPTIKEIR DQGSCGSCWA FGAVEAISDR
61
ICIHSNGRVN VEVSAEDMLT CCGGECGDGC NGGFPSGAWN FWTKKGLVSG GLYNSHVGCR
121
PYSIPPCEHH VNGSRPPCTG EGDTPKCSKT CEPGYSPSYK EDKHFGCSSY SVANNEKEIM
181
AEIYKNGPVE GAFSVYSDFL LYKSGVYQHV SGEIMGGHAI RILGWGVENG TPYWLVGNSW
241
NTDWGDNGFF KILRGQDHCG IESEIVAGMP CTHQY
301
i.
Cat. B/Aß40
(d)
Cat. B
Cat. B
Cat. B
Aß40
Aß40
Aß40
Aß40
ii.
Cat. B/Aß42
Aß42
Cat. B
Cat. B
Aß42
Cat. B
Aß42
0.5
μ
m