Pteroylglutamic acid (PGA) activity of serum in gel filtration

Carrier Proteins of Folic Acid Activity in Human Serum

“…In our earlier studies we have been able to show that serum FAA was divided into 3 maxima: the largest (about 60%) outside the protein band, a small portion (about 5%) in the band of large-molecular proteins, and the vast majority of the FAA of the protein band (about 30-35% of the total FAA) in the band of small-molecular proteins [3][4][5]. As a result of the present study, it was seen that the last mentioned FAA-carrying serum fraction was albumin.…”

“…The gel filtration of fresh sera taken from venous blood was carried out with Sephadex G-200 without protective agents, in the way described in detail previously [3], Unlike the former method, the molarity of the sodium phosphate buffer was 0.01 m , pH 7.0. The proteins of the fractions were determined with the Beckman DU equipment at a wave length of 280 /mi.…”

“…No separation was achieved either by ammonium sulphate precipitation or by repeated Sephadex filtrations. It appeared, furthermore, that the FAA of the protein band, on Sephadex G-200 filtra tion, was divided into 2 fractions [3]. One of these was filtered with the highmolecular proteins [4,5] and amounted to some 5% of the total serum FAA.…”

Binding of Folic Acid Activity by Body Fluids

“…It was centrifuged, and pure, non-haemolysed serum was separated and re-centrifuged for 20 min at a rate of 4000 rpm. After preliminary studies [8] had shown that preserving agents (ascorbic acid and mercaptoethanol) could essentially affect the distribution of FAA on filtration, and that a good FAA recovery was obtainable from natural serum in favourable conditions, all the filtrations in the present study were carried out without any preserving agents. The sera were filtered while they were fresh, and the technique described in connection with the preliminary studies [8] was followed in every detail.…”

“…2). The FAA activity of the fractions obtained was measured by the L.casei method as described earlier [8]. The protein determinations were carried out with the biuret reaction [8].…”