Fibroin-derive protein composition
AssigneeSilk Technologies, Ltd.
InventorsBrian D. Lawrence, David W. Infanger
Life of this patent
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Abstract
The invention provides a protein composition derived from silk fibroin, which composition possesses enhanced solubility and stability in aqueous solutions. The primary amino acid sequence of native fibroin is modified in the SDP such that cysteine disulfide bonds between the fibroin heavy and fibroin light protein chains are reduced or eliminated. Additionally, the composition can have a serine content that is reduced by greater than 40% compared to native fibroin protein, and the average molecular weight of the SDP is less than about 100 kDa.
Claims20
A fibroin-derived protein composition that possesses enhanced stability in an aqueous solution, wherein:
- the primary amino acid sequences of the fibroin-derived protein composition differ from native fibroin by at least by at least 4% with respect to the combined amino acid content of serine, glycine, and alanine, based on the combined absolute values of the differences in the content of serine, glycine, and alanine;
- cysteine disulfide bonds between the fibroin heavy and fibroin light protein chains of fibroin are reduced or eliminated;
- the protein composition has a serine content that is reduced by greater than 25% compared to native fibroin protein;
- wherein the average molecular weight of the fibroin-derived protein composition is 18.75 kDa to about 100 kDa;
- and
- the protein composition has an aqueous viscosity of less than 4 cP as a 10% w/w solution in water.
A fibroin-derived protein composition that possesses enhanced stability in aqueous solutions, wherein:
- the primary amino acid sequences of the fibroin-derived protein composition differ from native silk fibroin;
- cysteine disulfide bonds between the fibroin heavy and fibroin light protein chains are reduced or eliminated;
- the average molecular weight of the fibroin-derived protein is about 100 kDa and greater than 25 kDa;
- and
- the fibroin-derived protein composition maintains an optical absorbance at 550 nm of less than 0.25 for at least two hours after five seconds of ultrasonication.
A protein composition prepared by a process comprising heating an aqueous fibroin solution at an elevated pressure,
- wherein the aqueous fibroin solution comprises lithium bromide at a concentration of at least 8M, and
- wherein the aqueous fibroin solution is heated to at least about 105° C. (221° F.) under a pressure of about 10 PSI to about 20 PSI for at least about 20 minutes;
- to provide the protein composition, wherein the protein composition comprises less than 8.5% serine amino acid residues and the protein composition has an aqueous viscosity of less than 5 cP as a 10% w/w solution in water and an average molecular weight of 18.75 kDa to about 100 kDa.
Dependencies are inferred from the claim text.