Abstract
Ricin A chain was modified by the addition of the heptapeptide LRRASLG (Kemptide) and a histidine rag for bacterial expression. The mutagenized toxin was purified by nickel column and could be phosphorylated in vitro by protein kinase A as demonstrated by labeling with [γ-32P] ATP. Kemptide-A chain could be labeled even after reassociation with ricin B chain or disulfide linkage to antibody to form an immunotoxin. The 32P label in all cases was associated only with the A chain; ricin B chain and antibody were not kinase substrates alone or after conjugation. Kemptide-immunotoxin was tested in cytotoxicity assays and used to monitor internalization of the toxin moiety after [32P] phosphorylation.
Original language | English (US) |
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Pages (from-to) | 253-259 |
Number of pages | 7 |
Journal | Biochemical and Biophysical Research Communications |
Volume | 210 |
Issue number | 2 |
DOIs | |
State | Published - May 16 1995 |