JBC, Vol. 252, Issue 11, 3760-3765, Jun, 1977
Purification and properties of a membrane-associated, folate-binding protein from Lactobacillus casei
G. B. Henderson, E. M. Zevely and F. M. Huennekens
A folate-binding protein has been solubilized from Lactobacillus casei by
treatment of membrane preparations with Triton X-100 in the presence of
[3H]folate. The protein-folate complex was purified 100-fold and recovered
in a 22% yield by adsorption and elution from microgranular silica (Quso
G-32), followed by passage through Sephadex G-150. When subjected to sodium
dodecyl sulfate/polyacrylamide gel electrophoresis, the purified
preparations showed only a single, protein-staining band whose molecular
weight was 25,000. Bound folate (34 nmol/mg of protein) corresponded to
0.85 mol/mol of protein. Analyses of the protein revealed relatively few
charged or polar amino acids, an unusually high content of hydrophobic
residues and methionine, and the absence of cysteine. The purified
protein-folate complex was contained within a Triton micelle (molecular
weight, 220,000; about 340 mol of detergent per mol of protein). Bound
folate was retained when the micelle was exposed at 4 degrees to solutions
whose pH values ranged between 3 and 12; at 23 degrees, however, stability
was decreased, especially above pH 8. Folate could be released by treatment
of the micelle with ethanol or with chaotropic agents such as guanidinium
chloride, perchlorate, or thiocyanate.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
