title: Degradation of abnormal proteins in Escherichia coli. Differential proteolysis in vitro of E. coli alkaline phosphatase cyanogen-bromide-cleavage products.
abstract: Escherichia coli alkaline phosphatase has been purified and modified by either carboxymethylation or treatment with cyanogen bromide (CNBr). Only the CNBr-treated protein was degradable in an E. coli cell extract. Separation of the CNBr cleavage products by gel filtration in non-denaturing conditions gave rise to a number of oligomeric complexes, of which only those of molecular weight less than approximately 29000 were degradable in E. coli cell-free extracts. Carboxymethylation of the non-degradable complexes (greater than 29000 molecular weight) resulted in the formation of some complexes of less than 29000 molecular weight: such newly formed complexes were degradable by E. coli cell-free extracts. It is suggested that E. coli cell-free extracts may contain a protease/peptidase system which is active against peptide complexes below 29000 molecular weight, but inactive against peptide oligomers of greater molecular weight.
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism*; D003488:Cyanogen Bromide; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000201:enzymology*; D007700:Kinetics; D010446:Peptide Fragments / Q000302:isolation & purification; D010447:Peptide Hydrolases / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D010446:Peptide Fragments; D000469:Alkaline Phosphatase; D010447:Peptide Hydrolases; D003488:Cyanogen Bromide