| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for preparing extract, in which a middle silk gland as its ingredient can be picked out thickly and easily, and a cell-free protein synthetic method using the extract, in a cell-free protein synthetic system using a silkworm extract.SOLUTION: In the most common silkworm varieties, while the middle silk gland produces sericin which is a component of a cocoon, it is accompanied by accumulation of fibroin (the main protein of silk thread) produced in the posterior silk gland, making it improper to prepare extract due to fibroin's high viscoelasticity. Therefore, a middle silk gland of a crossbreed produced from a mutant silkworm strain which does not specifically produce fibroin, is used. The present inventors found that a middle silk gland can be picked out so easily by making a cut with scissors into a septum between appendages of abdominal third and fourth segments of the silkworm larva, and picking the middle silk gland from the cut with a tweezer. Using this method greatly shortens the time needed for preparation of cell extract, as it enables a silk gland to be picked out in 23 seconds per one larva in average which is one-sixth of the time required for the conventional posterior silk gland extraction, when compared. In addition, an enhanced protein synthetic ability is confirmed in the middle silk gland extract on the second or third day in the fifth instar and using the ability can allow cell-free protein synthesis to be provided, in which the extract is easily prepared. |
