Recombinant epidermal growth factor (EGF) and preparation method thereof

The invention discloses a recombinant epidermal growth factor (EGF) which is artificially synthesized in vitro. His 6-tag-SUMO (Small Ubiquitin-Like Modifier) protease identifying substrate is taken as an auxiliary fragment of protein soluble expression, EGF is taken as fused expression protein of a target fragment, the EGF is connected with a vector in positive sequence by a correct reading frame without a promoter and converted into an expression strain to finally construct fused protein which is in series connected with three expression substances. In the presence of imidazole, metal chelating medium is purified to obtain the fused protein with purity of 90% by one step, and enzyme digestion is carried out on the purified fused protein by utilizing SUMO protease with high specificity and high activity, so that a tag part HS and EGF target protein are dissociated, and the metal chelating medium is utilized to separate the tag part from the EGF target protein. A natural structure which has purity of 95% and has no first-place Met, and the target protein with activity of 2.2*10 IU/mg are obtained. And cost of every milligram of the recombinant epidermal growth factor is lowered to * Yuan from * Yuan.