| 摘要 |
pET11d-rOnc(Q1, M23L) DNA is subjected to two different site-directed mutations, each using an overlapping PCR protocol. One of the site-directed mutations changes the amino acid residue at position 23 of the encoded protein from leucine to methionine, whereby the encoded protein can be made into ranpirnase by cleaving the N-terminal methionine residue and allowing the adjacent glutamine residue to autocyclize. The other site-directed mutation changes the amino acid residue at position 72 of the encoded protein from serine to cysteine, thereby producing an encoded protein that can be made into a cysteinized ranpirnase by cleaving the N-terminal methionine residue and allowing the adjacent glutamine residue to autocyclize.
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