| 摘要 |
PURPOSE:To obtain an inexpensive polypeptide, consisting of an amino acid sequence in which amino acids of a specific polypeptide are partially substituted with other kinds of amino acids, having excellent specific activity and useful as a medicine for leukemia, etc. CONSTITUTION:Amino acids of an amino acid sequence of a human granulocytic colony stimulating factor (hG-CSF) polypeptide are partially substituted with other kinds of amino acids to provide a polypeptide (A). A DNA fragment coding the component (A) is then introduced into a plasmid DNA to afford a recombinant plasmid (e.g. pCfBD28) (B), which is used to transform Escherichia coli K-12HB101. The resultant transformant is selectively cultivated in an ampicillin-tolerant culture medium to provide Escherichia coli (C) holding the component (B). The strain (C) is then aerobically cultivated in a culture medium containing glucose, etc., at pH5.5-8.5 and 18-40 deg.C for 4-90hr. Microbial cells are subsequently collected from the obtained culture and subjected to crushing and extracting treatment to a collect the aimed polypeptide of hG-CSF. |
