| 摘要 |
Fusion proteins containing beta -galactosidase or a beta -galactosidase fragment preferably having more than 250 amino acids, but significantly less than the total sequence of beta -galactosidase, and a eukaryotic, genetically encodable polypeptide are insoluble and easy to isolate from bacterial cells. The purification of the polypeptides can be simplified by replacing interfering codons for methionine and/or arginine and/or cysteine in the beta -galactosidase gene fraction by codons for other amino acids. Genetically encodable polypeptides can therefore be obtained by coupling the structural gene for the desired polypeptide in the correct reading frame, if necessary via an adapter, to a gene for such a beta -galactosidase derivative via a regulation region, expressing the insoluble fusion protein in a bacterium, isolating this protein after cell disruption and liberating the desired polypeptide by chemical or enzymatic cleavage. The cleavage can be facilitated by adding a "polyamino acid arm", which is arranged between the polypeptide and the beta -galactosidase component. |
