Surfactant proteins A and D inhibit the growth of Gram-negative bacteria by increasing membrane permeability
J. Clin. Invest. Huixing Wu, et al. 111:1589 doi:10.1172/JCI16889 [Go to this article.]

Figure 2
Antimicrobial activity of calcium-bound surfactant-associated proteins. Human surfactant was repeatedly washed by sedimentation in the presence of calcium, eluted with EDTA, purified by mannose-Sepharose affinity chromatography, and size-fractionated by fast protein liquid chromatography on a Superose 6 column. (a) Elution of proteins from the column was monitored by UV absorbance at a wavelength of 280 nm. (b) The SP-A and SP-D content of individual fractions was determined by Western analysis. (c) The antimicrobial activity of the original sample and selected fractions, including 8, 12, and the tenfold concentrate of fraction 21, was assessed by measurement of ³H-uridine incorporation in E. coli K12. Controls shown included protein-free ultrafiltrates (molecular weight cutoff of 10,000) of the most concentrated sample used in each set (designated F), and 2 mM EDTA, the highest possible concentration of EDTA in any sample. Data are mean ± SEM; n = 3; *P < 0.01.