[The molecular cloning and sequencing of the cobra serum antitoxic protein gene]

In the previous study the authors found at least one peptide of 39 amino acid residues of several purified tryptic-fragments of the cobra serum antitoxic protein (CSAP), whose sequence had shown certain correlation with the rat serum albumin. For further clarification of the toxin-binding activity of CSAP in relation with its corresponding structure, the cDNA gene library of cobra liver cells was established and DNA primers were designed according to the known amino acid sequences of the tryptic peptides of CSAP. The specific probes were prepared and the specific clone was screened out from the library by PCR. Finally, the CSAP cDNA was sequenced from its sub-clones. Then the complete amino acid sequence of CSAP was elucidated. It is a polypeptide chain of 614 amino acid residues with a molecular size of 69.8 KDa. In comparing the whole sequence of CSAP, especially its signal peptide, with mammalian serum albumins, the authors have come to realize that CSAP is just the cobra serum albumin (CSA).