Catabolic attacks of membrane-bound angiotensin-converting enzyme on the N-terminal part of species-specific amyloid-beta peptides.
Catabolic processes play a crucial role in the steady state of the amyloid-beta peptide (Abeta). Neprilysin (NEP) and angiotensin-converting enzyme (ACE), two transmembranal enzymes with greatest importance in peptide pharmacology, are known to play a role in Abeta catabolism. This paper focuses on the N-terminal part of Abeta. This region contains the three amino acid residues that determine the differences between human (hAbeta) and murine Abeta (mAbeta). Moreover, the N-terminal part of Abeta contains the zinc-binding site of the molecule. Consequently, all hydrolytic attacks on this part of the Alzheimer peptide should be of exceptional interest. We investigated domain-selective forms of ACE in HPLC-monitored peptide degradation studies and used mass spectrometry for product analyses. We found that ACE-evoked a hydrolysis of the N-terminal part of m- and hAbeta. The hAbeta sequence hAbeta (4-15) was found to be a better substrate for ACE compared to the corresponding murine form. Moreover, we localized the corresponding cleavage sites in the N-terminal part of Abeta as well as in the full-length molecule and identified new sites of endopeptidolytic attack by ACE. Finally, we demonstrate that both catalytic domains of mACE have similar hydrolytic activity on the N-terminal part of Abeta. Our results show that ACE besides its typical function as a dipeptidyl-carboxypeptidase has also unequivocal endopeptidolytic activities.
Sun
Xiaoou
X
Leibniz-Institut für Molekulare Pharmakologie (FMP), D-13125 Berlin, Germany.
Becker
Matthias
M
Pankow
Kristin
K
Krause
Eberhard
E
Ringling
Martina
M
Beyermann
Michael
M
Maul
Bjoern
B
Walther
Thomas
T
Siems
Wolf-Eberhard
WE
D000595:Amino Acid Sequence; D016229:Amyloid beta-Peptides / Q000378:metabolism*; D000818:Animals; D016466:CHO Cells; D002384:Catalysis; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology*; D002851:Chromatography, High Pressure Liquid; D003001:Cloning, Molecular; D006224:Cricetinae; D003412:Cricetulus; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D010446:Peptide Fragments / Q000378:metabolism; D010455:Peptides / Q000378:metabolism; D007703:Peptidyl-Dipeptidase A / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013045:Species Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D016229:Amyloid beta-Peptides; D010446:Peptide Fragments; D010455:Peptides; D011994:Recombinant Proteins; D007703:Peptidyl-Dipeptidase A