• Purity

  >90%, by SDS-PAGE under reducing conditions and visualized by silver stain

• Endotoxin Level

  <0.01 EU per 1 μg of the protein by the LAL method.  

• Activity

  Measured by its ability to inhibit LPS-induced IL-8 secretion by THP-1 human acute monocytic leukemia cells. Wilde, C.G.     et al. (1994) J. Biol. Chem.     269:17411. The ED    ₅₀ for this effect is 0.4-2.4 ng/mL.

• Source

  Human embryonic kidney cell, HEK293-derived

  Human BPI (Val32-Lys487) Accession # AAA51841	IEGRMD	Human IgG1 (Pro100-Lys330)
  N-terminus		C-terminus

• Accession #

• N-terminal Sequence    
  Analysis

  Val32

• Structure / Form

  Disulfide-linked homodimer

• Predicted Molecular Mass

  77.3 kDa (monomer)

• SDS-PAGE

  75-85 kDa, reducing conditions

Background: BPI

Bactericidal/Permeability Increasing protein (BPI) is a 55 kDa antibacterial glycoprotein that plays a role in innate immunity (1, 2). It belongs to the lipid transfer protein family that also includes LPS binding protein (LBP), cholesteryl ester transfer protein (CETP), and phospholipid transfer protein (PLTP). Circulating levels of BPI are positively correlated with the levels of cholesterol, LDL cholesterol, and HDL cholesterol (3). Mature human BPI shares approximately 55% amino acid (aa) sequence identity with mouse and rat BPI. It can be seceted as a monomer or as a disulfide‑linked homodimer (4). It consists of a highly basic N‑terminal and a hydrophobic C‑terminal domain (5). Its N‑terminal domain confers the ability of BPI to bind bacterial lipopolysaccharide (LPS) found in the cell walls of Gram negative bacteria and to induce the lysis and phagocytosis of these bacteria (6‑9). It also blocks the endothelial cell response to endotoxin (10). BPI is stored in neutrophil and eosinophil granules for induced secretion during inflammation (11, 12). It is additionally expressed in mucosal epithelia and testis (10, 13). BPI can be retained on the surface of both neutrophils and epithelial cells, presumably by its hydrophobic C‑terminal domain (8, 10). BPI also functions as an anti-angiogenic molecule by inhibiting vascular endothelial cell proliferation and tubule formation (14). Like the antibacterial actions, this function is mediated by the N‑terminal region (15).

• References:

1. Schultz, H. and J.P. Weiss (2007) Clin. Chim. Acta 384:12.

2. Holweg, A. et al. (2011) Biochem. Soc. Trans. 39:1045.

3. Esteve, E. et al. (2010) Thromb. Haemost. 103:780.

4. Horwitz, A.H. et al. (1996) Protein Exp. Purif. 8:28.

5. Gray, P.W. et al. (1989) J. Biol. Chem. 264:9505.

6. Ooi, C.E. et al. (1987) J. Biol. Chem. 262:14891.

7. Tobias, P.S. et al. (1997) J. Biol. Chem. 272:18682.

8. Weersink, A.J. et al. (1993) J. Immunol. 150:253.

9. Nishimura, H. et al. (2001) Immunology 103:519.

10. Canny, G. et al. (2002) Proc. Natl. Acad. Sci. 99:3902.

11. Weiss, J. and I. Olsson (1987) Blood 69:652.

12. Calafat, J. et al. (1998) Blood 91:4770.

13. Lennartsson, A. et al. (2005) J. Leukoc. Biol. 77:369.

14. van der Schaft, D.W.J. et al. (2000) Blood 96:176.

15. Rauniyar, R.K. et al. (2002) Invest. Ophthalmol. Vis. Sci. 43:503.

• Long Name:

  Bactericidal/Permeability-increasing Protein

• Entrez Gene IDs:

  671 (Human); 329547 (Mouse); 296321 (Rat)

• Alternate Names:

  bactericidal permeability-increasing protein; bactericidal/permeability-increasing protein; BPI; BPIFD1; CAP 57; rBPI