The purification and characterization of the low molecular weight human folate binding protein using affinity chromatography.

The low molecular weight folate binding protein (FABP) has been purified 1000-fold to a specific activity of 7.2 gamma g of pteroylglutamic acid (PGA) bound per mg of protein. This purified FABP represents two protein bands that bind PGA on polyacrylamide disc gel electrophoreis, elutes from DEAE-cellulose in 0.001 M phosphate buffer, stains positive with PAS, Elutes from concanavalin A Sepharose affinity columns with methyl alpha-mannoside, and shows three major peaks (pl =6.8, 7.5, 8.2) by isotric focusing. The binding of PGA to purified FABP dependent on pH and is inhibited by urea...