Binding proteins to the constant region of immunoglobulin G

1. A polypeptide comprising the amino acid sequence of general formula 1 Z1-Z2-Z3 (SEQ ID NO: 1), wherein

Z1 is EY(A/C)VSxTADxxxH (SEQ ID NO: 184);

Z2 is GxxxxLxRxAVKGxKP (SEQ ID NO: 185); and

Z3 is a xxxQQxxFYMxxx (SEQ ID NO: 186),

wherein x is any amino acid.

2. The polypeptide of claim 1 , wherein Z1 is selected from the group consisting of

(SEQ ID NO: 15)

EYCVSRTAVDAKKH;

(SEQ ID NO: 16)

EYAVSRTAVDALKH;

(SEQ ID NO: 17)

EYCVSRTAVDALKH;

(SEQ ID NO: 18)

EY(A/C)VSRTA(E/V/L/M/A/I/T)DALKH;

(SEQ ID NO: 19)

EY(A/C)VSRTA(E/V/L/R/M/A)DALKH;

(SEQ ID NO: 20)

EY(A/C)VSRTA(E/V/M/A/I/T)DALKH;

(SEQ ID NO: 21)

EY(A/C)VSRTAVDALKH;

(SEQ ID NO: 22)

EY(A/C)VSRTA(V/M)DALKH;

(SEQ ID NO: 23)

EY(A/C)VSRTAMDALKH;

(SEQ ID NO: 24)

EY(A/C)VSRTAADALKH;

(SEQ ID NO: 25)

EY(A/C)VSRTAMDALKH;

(SEQ ID NO: 26)

EY(A/C)VSRTALDALKH;

(SEQ ID NO: 27)

EY(A/C)VSRTAIDALKH;

(SEQ ID NO: 28)

EY(A/C)VSRTATDALKH;

(SEQ ID NO: 29)

EY(A/C)VSRTAVDALKH

(SEQ ID NO: 30)

EYAVSRTAMDALKH;

(SEQ ID NO: 31)

EYAVSRTAADALKH;

(SEQ ID NO: 32)

EYAVSRTAMDALKH;

(SEQ ID NO: 33)

EYAVSRTALDALKH;

(SEQ ID NO: 34)

EYAVSRTAIDALKH;

(SEQ ID NO: 35)

EYAVSRTATDALKH;

(SEQ ID NO: 36)

EYCVSRTAMDALKH;

(SEQ ID NO: 37)

EYCVSRTAADALKH;

(SEQ ID NO: 38)

EYCVSRTAMDALKH;

(SEQ ID NO: 39)

EYCVSRTALDALKH;

(SEQ ID NO: 40)

EYCVSRTAIDALKH;

and

(SEQ ID NO: 41)

EYCVSRTATDALKH.

3. The polypeptide of claim 1 , wherein Z3 is selected from the group consisting of:

(SEQ ID NO: 47)

EMEQQAFFYMKLR;

(SEQ ID NO: 48)

EMEQQALFYMKLR;

(SEQ ID NO: 49)

TFEQQSFFYMSLK;

(SEQ ID NO: 51)

(B5)(B6)EQQ(S/A)(F/L)FYM(B5)L(K/R),

where B5 and B6 are independently any amino acid;

(SEQ ID NO: 52)

(G/R/S/M/P/W/V/T/R)(M/L/I/A/E/F)EQQ(S/A)

(F/L)FYM(B5)L(K/R);

(SEQ ID NO: 53)

(V/H/K/W)(M/W/I/L/H)EQQ(S/A)(F/L)FYM(B5)L(K/R);

(SEQ ID NO: 54)

EMEQQALFYMKLK;

(SEQ ID NO: 55)

VWEQQSFFYMVLK;

(SEQ ID NO: 56)

HWEQQSFFYMLLK;

(SEQ ID NO: 57)

HMEQQSFFYMMLK;

(SEQ ID NO: 58)

KIEQQSFFYMMLK;

(SEQ ID NO: 59)

WLEQQSFFYMALK;

(SEQ ID NO: 60)

WLEQQSFFYMQLK;

(SEQ ID NO: 61)

WLEQQAFFYMELK;

(SEQ ID NO: 62)

WLEQQSFFYMKLK;

(SEQ ID NO: 63)

FLEQQSFFYMRLK;

(SEQ ID NO: 64)

WHEQQSFFYMMLK;

(SEQ ID NO: 65)

WHEQQSFFYMRLK;

(SEQ ID NO: 66)

EMEQQALFYMKLK;

(SEQ ID NO: 67)

GMEQQSFFYMILK;

(SEQ ID NO: 68)

RLEQQSFFYMTLK;

(SEQ ID NO: 69)

SLEQQSFFYMNLK;

(SEQ ID NO: 70)

MIEQQSFFYMRLK;

(SEQ ID NO: 71)

PIEQQSFFYMHLK;

(SEQ ID NO: 72)

WLEQQSFFYMHLK;

(SEQ ID NO: 73)

VLEQQSFFYMDLK;

(SEQ ID NO: 74)

WAEQQSFFYMGLK;

(SEQ ID NO: 75)

TEEQQSFFYMTLK;

(SEQ ID NO: 76)

TFEQQSFFYMSLK;

and

(SEQ ID NO: 77)

RLEQQSFFYMSLK.

4. The polypeptide of claim 1 , wherein Z2 has the amino acid sequence

(SEQ ID NO: 85)

G(F/V)(E/D)(V/G)(Y/C)L(L/F)R(D/E/N)AVKG(I/V/F)KP.

5. The polypeptide of claim 1 , wherein the polypeptide comprises one of the following amino acid sequences selected from the group consisting of SEQ ID NOs: 117-119.

6. The polypeptide of claim 1 , wherein the polypeptide comprises the amino acid sequence of general formula 5, Z4-Z1-Z2-Z3 (SEQ ID NO: 8), wherein Z4 is a peptide of at least between 100-200 amino acids in length.

7. The polypeptide of claim 6 , wherein Z4 comprises the amino acid sequence of SEQ ID NO: 120.

8. The polypeptide of claim 1 , wherein the polypeptide comprises one of the following amino acid sequences selected from the group consisting of SEQ ID NOs: 141-169 and 172-182.

9. A pharmaceutical composition comprising the polypeptide of claim 1 and a pharmaceutically acceptable carrier.

10. A composition, comprising the polypeptide of claim 1 =bound to a solid support.

11. The polypeptide of claim 1 , wherein the polypeptide comprises the amino acid sequence of SEQ ID NO:143.

12. The polypeptide of claim 2 , wherein Z3 is selected from the group consisting of SEQ ID NOs: 47-49 and 51-77.

13. The polypeptide of claim 2 , wherein Z2 has the amino acid sequence of SEQ ID NO:85.

14. The polypeptide of claim 12 wherein Z2 has the amino acid sequence of SEQ ID NO:85.

15. The polypeptide of claim 3 wherein Z2 has the amino acid sequence of SEQ ID NO:85.

16. A method for purifying antibodies or Fc fusion proteins, comprising

(a) contacting a sample comprising antibodies or Fc fusion proteins with one or more polypeptides according to claim 1 under suitable conditions for binding of antibodies in the sample to the one or more polypeptides to form antibody-polypeptide complexes; and

(b) dissociating the antibody from the antibody-polypeptide complexes, to isolate the antibody.

17. A method for detection of an antibody or Fc fusion protein in a sample, comprising

(a) contacting a sample comprising antibodies or Fc fusion proteins with one or more polypeptides according to claim 1 under suitable conditions for binding of antibodies or Fc fusion protein in the sample to the one or more polypeptides to form antibody-polypeptide complexes; and

(b) detecting the antibody-polypeptide complexes.