Production of Recombinant Oxytocin Through Sulfitolysis of Inteincontaining Fusion Protein
2012
An artificial gene consisting of seven copies of an oxytocinoyl-lysine encoding sequence arranged in a tandem
was synthesized and inserted downstream of the SspDnaB intein gene in a pTWIN1 plasmid. The corresponding fusion
protein Dnab-7oxy contained 16 cysteine residues and formed inclusion bodies when expressed in E. coli. The standard
protocol involving solubilization of the fusion protein and its autocatalytic cleavage on a chitin resin was not effective because
of a very low yield of the cleavage reaction. Attempts to perform a refolding of the intein part of the fusion protein
in solution were also unsuccessful because of a high level of protein aggregation. Sulfitolysis of cysteine residues is
known to increase a solubility of proteins and peptides. Therefore we suggested a one-step approach that combines solubilization
of inclusion bodies and sulfitolysis of a hybrid protein. The fusion protein was completely reduced and solubilized
in 8M urea at pH 9.0 in the presence of sodium sulfite and sodium tetrathionate. The sulfitized protein was loaded onto a
chitin column, an efficient cleavage was induced by a pH shift from 9.0 to 6.5, and seven successively connected oxytocinoyl-
lysine units were released. The heptamer was subjected to trypsinolysis yielding sulfitized monomers of oxytocinoyllysine.
Oxytocinoyl-lysine was refolded as described previously and treated by carboxypeptidase B to form the oxytocinic
acid. The target oxytocin amide was then synthesized via methyl ester intermediate. Using this approach 6 mg of recombinant
oxytocin can be obtained from 1 g of biomass.
Keywords:
- Correction
- Source
- Cite
- Save
- Machine Reading By IdeaReader
0
References
3
Citations
NaN
KQI