| 摘要 |
PURPOSE:To keep the sugar chain of a product in high-mannose-type in the use of a yeast subjected to mutagenic treatment as a host, by culturing the yeast at a low temperature and then transferring to a high-temperature environment to induce the expression of the product. CONSTITUTION:A yeast belonging to Saccharomyces cerevisiae genus, e.g. EHA-1C, is treated by <3>H-mannose suicide process to obtain a high-temperature sensitive sugar chain mutant strain EHF-2C. The mutant is cultured at a low temperature (e.g. about 20-30 deg.C) e.g. in YPD medium and grown until a sufficient amount of the microbial cells are produced. The cells are transferred to a high-temperature environment (about 35-40 deg.C) and, at the same time, cultured under a condition to induce the expression of the product. Since the mutant is incapable of adding outer chain at a high temperature, the sugar chain of the product is composed solely of mannose core. Similar to the conventional yeast, the product is easily secreted from the cell. The sugar chain of the product has short length to be held in the core chain and the product can be extremely easily secreted.
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