CHEMICALLY MODIFIED ENGINEERED SPIDER SILK PROTEINS

1 . A recombinant spidroin comprising from 244 to 623 amino acid residues and defined by the formula NT-(Rep) x -C wherein:

an N-terminal domain NT consisting of 130 to156 amino acid residues derived from the N-terminal domain of a spidroin;

a repetitive domain (Rep) x consisting of from 87 to 463 amino acid residues derived from the repetitive sequences in a spidroin, wherein x is a number of repetitive sequences from 1 to 8;

a domain C is Cys (Z) residue, where Z is optional, if present, is selected from the group Ala, Arg, Asn, Asp, Cys, Glu, Gln, Gly, His, Ile, Leu, Lys, Met, Phe, Pro, Ser, The, Trp, Tyr, Val.

2 . The recombinant spidroin according to claim 1 , wherein a domain C is Cys.

3 . The recombinant spidroin according to claim 1 , wherein a domain Cis CysAla.

4 . The recombinant spidroin according to claim 1 , wherein (Rep) x -domain preferably consists of 174-463 amino acid residues.

5 . A method of bioconjugation of the recombinant spidroin comprising the steps of:

a) reducing the disulfide bond to obtain free thiol group with tris(2-carboxyethyl) phosphine, wherein the reaction temperature is in range from 2 to 10° C. and pH is in the range from 6.0 to 9.0.

b) quenching of obtained product in step a) with 1,2-bis(2-azidoethoxy)ethane;

c) coupling the product obtained in step b) with 2- to 8-arm polyethylene glycol maleimide (PEG-Mal);

d) forming the bioconjugated recombinant spidroin.

6 . The method according to claim 5 wherein the pH in step a) is preferably in range from 7.2 to 7.5.

7 . The method according to claim 5 wherein the temperature in step a) is preferably in range from 3° C. to 5° C.

8 . A bioconjugated recombinant spidroin comprising from 244 to 623 amino acid residues and defined by the formula (NT-(Rep) x -C) y -PEG-Mal wherein:

an N-terminal domain NT consisting of 130 to 156 amino acid residues derived from the N-terminal domain of a spidroin;

a repetitive domain (Rep) consisting of 87 to 463 amino acid residues derived from the repetitive sequences in a spidroin, wherein x is a number of repetitive sequences from 1 to 8;

a domain C is Cys (Z) residue, where Z is optional, if present, is selected from the group Ala, Arg, Asn, Asp, Cys, Glu, Gln, Gly, His, Ile, Leu, Lys, Met, Phe, Pro, Ser, The, Trp, Tyr, Val;

y is a number of bioconjugated NT-(Rep) x -C proteins from 1 to 8;

PEG-Mal is 2- to 8-arm polyethylene glycol maleimide;

and optical isomers thereof.

9 . The bioconjugated recombinant spidroin according to claim 8 which has a structure:

wherein:

n is an integer selected from 50 to 400, corresponding to an average molecular weight between 5000 Da and 10000 Da;

x is a number of repetitive sequences from 1 to 8;

C is Cys (Z) residue where Z is optional, if present, is selected from the group Ala, Arg, Asn, Asp, Cys, Glu, Gln, Gly, His, Ile, Leu, Lys, Met, Phe, Pro, Ser, The, Trp, Tyr, Val.

10 . The bioconjugated recombinant spidroin according to claim 8 which has a structure:

wherein:

R1 is pentaerythritol core;

n is an integer selected from 50 to 400, corresponding to an average molecular weight between 5000 Da and 10000 Da;

x is a number of repetitive sequences from 1 to 8;

C is Cys (Z) residue where Z is optional, if present, is selected from the group Ala, Arg, Asn, Asp, Cys, Glu, Gln, Gly, His, Ile, Leu, Lys, Met, Phe, Pro, Ser, The, Trp, Tyr, Val.

11 . The bioconjugated recombinant spidroin according to claim 8 which has a structure:

R2 is tripentaerythritol core;

n is an integer selected from 50 to 400, corresponding to an average molecular weight between 5000 Da and 10000 Da;

x is a number of repetitive sequences from 1 to 8;

C is Cys (Z) residue where Z is optional, if present, is selected from the group Ala, Arg, Asn, Asp, Cys, Glu, Gln, Gly, His, Ile, Leu, Lys, Met, Phe, Pro, Ser, The, Trp, Tyr, Val.

12 . A bioconjugated recombinant spidroins for use in regenerative medicine.

13 . The bioconjugated recombinant spidroins according to claim 12 for use as a cell culture scaffold.