Molecular and biochemical properties of the ATP-stimulated multicatalytic proteinase, ingensin, from rat liver.
1. A high-molecular-mass multicatalytic proteinase, ingensin, has been purified from rat liver and biochemically characterized. Trypsinization in the presence of ATP prevented the degradation of ingensin subunits. 2. Glutaraldehyde, which copolymerizes proteins, increased the apparent molecular mass of the subunits on SDS-PAGE, indicating the occurrence of covalent crosslinking of subunits. ATP, in this case, lowered the extent of covalent crosslinking. These results suggest that ATP altered the conformation of ingensin subunits. 3. Urea-induced autodigestion experiments demonstrated that some low-molecular-weight subunits selectively disappeared without changes in the contents of other subunits. The chymotryptic activity of the proteinase was more resistant to autodigestion than its tryptic activity. Therefore, we conclude that separate subunits of the enzyme are responsible for the different peptide-hydrolyzing activities.
Ishiura
S
S
National Institute of Neuroscience, NCNP, Tokyo, Japan.
Tsukahara
T
T
Sugita
H
H
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D003546:Cysteine Endopeptidases / Q000737:chemistry / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005976:Glutaral / Q000494:pharmacology; D008099:Liver / Q000737:chemistry*; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009097:Multienzyme Complexes / Q000737:chemistry / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex; D011487:Protein Conformation / Q000187:drug effects; D051381:Rats; D014357:Trypsin / Q000378:metabolism; D014508:Urea / Q000494:pharmacology
D046911:Macromolecular Substances; D009097:Multienzyme Complexes; D010455:Peptides; D000255:Adenosine Triphosphate; D014508:Urea; D014357:Trypsin; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; D005976:Glutaral