amyloid-beta-peptides has been researched along with pepstatin* in 2 studies
2 other study(ies) available for amyloid-beta-peptides and pepstatin
| Article | Year |
|---|---|
A novel gamma -secretase assay based on detection of the putative C-terminal fragment-gamma of amyloid beta protein precursor.
Alzheimer's disease is characterized by the deposits of the 4-kDa amyloid beta peptide (A beta). The A beta protein precursor (APP) is cleaved by beta-secretase to generate a C-terminal fragment, CTF beta, which in turn is cleaved by gamma-secretase to generate A beta. Alternative cleavage of the APP by alpha-secretase at A beta 16/17 generates the C-terminal fragment, CTFalpha. In addition to A beta, endoproteolytic cleavage of CTF alpha and CTF beta by gamma-secretase should yield a C-terminal fragment of 57-59 residues (CTF gamma). However, CTF gamma has not yet been reported in either brain or cell lysates, presumably due to its instability in vivo. We detected the in vitro generation of A beta as well as an approximately 6-kDa fragment from guinea pig brain membranes. We have provided biochemical and pharmacological evidence that this 6-kDa fragment is the elusive CTF gamma, and we describe an in vitro assay for gamma-secretase activity. The fragment migrates with a synthetic peptide corresponding to the 57-residue CTF gamma fragment. Three compounds previously identified as gamma-secretase inhibitors, pepstatin-A, MG132, and a substrate-based difluoroketone (t-butoxycarbonyl-Val-Ile-(S)-4-amino-3-oxo-2, 2-difluoropentanoyl-Val-Ile-OMe), reduced the yield of CTF gamma, providing additional evidence that the fragment arises from gamma-secretase cleavage. Consistent with reports that presenilins are the elusive gamma-secretases, subcellular fractionation studies showed that presenilin-1, CTF alpha, and CTF beta are enriched in the CTF gamma-generating fractions. The in vitro gamma-secretase assay described here will be useful for the detailed characterization of the enzyme and to screen for gamma-secretase inhibitors. Topics: Alzheimer Disease; Amyloid beta-Peptides; Amyloid beta-Protein Precursor; Amyloid Precursor Protein Secretases; Animals; Brain; Caspase 3; Caspases; Cells, Cultured; Detergents; Endopeptidases; Guinea Pigs; Hydrogen-Ion Concentration; Membrane Proteins; Molecular Weight; Pepstatins; Peptide Fragments; Phenanthrolines; Protease Inhibitors; Protein Processing, Post-Translational; Solubility; Subcellular Fractions | 2001 |
Carboxy-terminal truncation of long-tailed amyloid beta-peptide is inhibited by serine protease inhibitor and peptide aldehyde.
The 42/43-residue amyloid beta-peptide (Abeta) is widely believed to play a major role in Alzheimer's disease. The present study shows that the rat brain contains a carboxypeptidase that efficiently deletes three amino acids from Abeta1-43. The carboxypeptidase activity in the brain was completely inhibited by 1 mM phenylmethylsulfonyl fluoride, suggesting the protease is a serine carboxypeptidase. The carboxy-terminal truncation of Abeta1-43 was moderately inhibited by carbobenzoxy-Leu-leucinal, carbobenzoxy-Leu-Leu-leucinal, and carbobenzoxy-Leu-Leu-norvalinal, and weakly by antipain. The present data suggest that the serine carboxypeptidase contributes to the generation of short-tailed Abeta peptides and is important in the intracellular clearance of Abeta1-42/43 in brains. Topics: Amino Acids; Amyloid beta-Peptides; Animals; Antipain; Brain; Carboxypeptidases; Chloromercuribenzoates; Edetic Acid; Leupeptins; p-Chloromercuribenzoic Acid; Pepstatins; Peptide Fragments; Phenylmethylsulfonyl Fluoride; Rats; Serine Proteinase Inhibitors | 1998 |