Protein Production Business using Transgenic Silkworms related FAQ

A.It can be used as the coating material for cell culture dishes. Because it does not contain any animal-derived ingredients, it can be used for xeno-free cultures. However, Neosilk-Human Collagen I does not have triple-helical structure, and for this reason there are times the adhesive ratio is low for certain cell types. In addition, it does not form a collagen gel, so it cannot be used for collagen gel cultures.

A.It depends on the expressed protein. For antibody (IgG), it is approximately 0.3 to 2.0 mg per cocoon.

A.In the expression system, proteins are secreted in cocoons, so essentially only secreted proteins can be expressed. However, we have experienced success with expressing the extracellular domain of a membrane protein and an intercellular soluble protein that bind to the signal peptide. Although it is also possible to express the membrane protein and intercellular protein in the silk gland cells and collect the protein from the silk glands, we generally do not recommend this because the purification process is complicated.

A.No, the targeted protein is not expressed as a fusion protein with sericin. It is expressed as an independent protein. For this reason, there is no need to use an enzyme to conduct cleaving for purification.

A.A sugar chain is added to the protein produced from transgenic silkworms. For an N-linked sugar chain, generally speaking a paucimannose-type short sugar chain is known to be added to the glycoprotein synthesized by insects. On the other hand, we discovered that a complex-type sugar chain containing N-acetylglucosamine at the non-reducing ends is added to proteins produced in the silk gland of silkworms. We have also confirmed that the core fucose of the sugar chain base (α1, 3-fucose and α1, 6-fucose) does not exist in the antibodies and fibrinogen produced from transgenic silkworms. It is also known that antibodies which do not have α1, 6-fucose in the sugar chain have a high level of ADCC activity (Antibody-Dependent Cellular Cytotoxicity activity).

A.We basically believe that it is possible, although no actual cases exist at this time. We are preparing to construct a manufacturing plant that is GMP compliant because we aim to manufacture fibrinogen, vaccines and antibody drugs in future.

A.No they are not. Because the transgenic silkworm-based protein production system does not use viruses, the host organisms subject to the Cartagena protocol are the silkworms. The proteins extracted from the cocoons do not contain the host organism (transgenic silkworm), so they are not subject to the Cartagena protocol.

A.Yes, they are basically equivalent.

A.We normally extract proteins using a neutral pH buffer added to a non-ionic detergnet, such as TritonX-100. For this reason, the majority of the proteins are not denatured during the extraction process. However, in rare cases we are required to use high-concentrated urea for extraction. In these cases, some types of protein are denatured.

A.Because we can extract the targeted protein with a high level of purity from the cocoons, there is no need to add a tag for purification. If you wish to add a tag, we recommend the His-tag.