“…On the other hand, the FAA attached to protein fractions seems to be firmly bound, since it tolerates, e.g., an ammonium sulphate precipitation and repeated gel filtrations without abandoning its attachment to the corresponding proteins [unpublished data], FAA recovery in these cases was nearly 100%. Similar results concerning the occurrence of FAA in-and outside the protein band have been reported by Retief and H uskisson [6,7], Their absorption studies with charcoal pre parations coated with molecules of varying size suggested that the main serum folate binder is of molecular weight 70,000-120,000. Since the mole cular weight of albumin is 69,000, it seems probable that the conclusion of these authors concerning the FAA-carrying protein agrees with our finding.…”