Purification and characterization of a ubenimex (Bestatin)-sensitive aminopeptidase B-like enzyme from K562 human chronic myeloid leukemia cells.
A ubenimex-sensitive aminopeptidase B-like enzyme was purified from the non-membrane-bound fraction of K562 cells by a series of chromatographic procedures and slab-gel electrophoresis. The apparent molecular mass of the enzyme was estimated to be 73 kDa by SDS-PAGE. The aminopeptidase activity was activated by chloride ions and inhibited by Zn2+, Cu2+, Cd2+, and p-chloromercuribenzoic acid. Ubenimex was a potent inhibitor of this aminopeptidase in the nanomolar range. The sequence of the N-terminus of the protein was not determined. Partial amino acid sequencing revealed that the N-terminus of this aminopeptidase B-like enzyme was blocked by acylation. The partial sequences of the two fragments produced by CNBr cleavage and an acylamino acid-releasing reaction showed this enzyme to be a new aminopeptidase.
Yamada
M
M
Research Laboratories, Nippon Kayaku Co., Tokyo, Japan.
Sukenaga
Y
Y
Fujii
H
H
Abe
F
F
Takeuchi
T
T
D000595:Amino Acid Sequence; D000626:Aminopeptidases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D002413:Cations, Divalent / Q000494:pharmacology; D002712:Chlorides / Q000494:pharmacology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007930:Leucine / Q000031:analogs & derivatives* / Q000494:pharmacology; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000201:enzymology*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D013379:Substrate Specificity; D014407:Tumor Cells, Cultured
D002413:Cations, Divalent; D002712:Chlorides; D000626:Aminopeptidases; C019721:aminopeptidase B; D007930:Leucine; C012211:ubenimex