Abstract: The present disclosure discloses a method for expressing and preparing a bivalent bispecific antibody. In the present disclosure, each portion of a bivalent bispecific antibody and an immune hybrid protein thereof is respectively expressed in a suitable prokaryotic or eukaryotic cell system, separated and purified by high-performance affinity chromatography, and then spliced in vitro by trans-splicing reaction mediated by an intein, to prepare the bivalent specific antibody and an immune hybrid protein thereof.

Abstract: Provided is a polypeptide combination, a targeting component thereof comprising a shielding peptide, a cleavable part, an antigen-binding part and a first intein fragment, the shielding peptide and the antigen-binding part being connected by means of the cleavable part, and the antigen-binding part being directly or indirectly connected to the first intein fragment; a toxin component thereof comprises a second intein fragment and a toxin, and the second intein fragment is directly or indirectly connected to the toxin; the targeting component and the toxin component form an immunoconjugate by means of the interactive action between the first intein fragment and the second intein fragment; in the immunoconjugate, the shielding peptide and the antigen-binding part are connected by means of the cleavable part, and the antigen-binding part is connected to the toxin. Also provided are a preparation method and a pharmaceutical use for the polypeptide combination.

Abstract: A polypeptide composition, and methods of making the same, may include a first polypeptide and a second polypeptide, wherein the first polypeptide comprise a first toxin fragment and a first intein fragment, the second polypeptide comprise a second toxin fragment and a second intein fragment, the first polypeptide is different from the second polypeptide; the first toxin fragment and the second toxin fragment are non-biotoxic; the first polypeptide and the second polypeptide may make the first toxin fragment and the second toxin fragment into biotoxic toxins by means of the interaction of the first intein fragment and the second intein fragment. Kits may include such first and second polypeptides, and such compositions and kits may be used in treating tumors.

Abstract: Methods for preparing a recombinant protein from a bacterium are provided. The method includes constructing an expression vector including two promoters. Each of the two promoters attaches a secretion signal peptide to one polypeptide of a protein. The protein attached with the two promoters and secretion signal peptides is then cloned into the expression vector to provide a recombinant expression plasmid. The recombinant expression plasmid is transformed into a host cell. A fermentation process is performed to grow the host cell and to induce an expression to synthesize polypeptides in the host cell and to transport the polypeptides to an outside of a cytoplasm of the host cell, such that the polypeptides are released in a soluble form in a growth medium of the host cell. The polypeptides are assembled into a three-dimensional structure of the protein. The protein is captured from the growth medium.