Folic Acid Binding by Human Plasma Albumin

Abstract

Binding of [³H]folate to pure human plasma albumin was studied by Sephadex G-200 gel filtration in a steady-state system. The experiments showed the presence of two binding sites per molecule of albumin and an equilibrium constant of 0.9x10³ 1/mol. With normal human plasma, only albumin bound exogenous [³H]folate with nearly the same equilibrium constant. In human blood plasma at concentrations of less than 10^-5 mol/1, 50% of folate was free, and 50% was bound to albumin. Binding was maximal at about pH 6 and negligible above pH 8 and below pH 4.5. Neither human transferrin nor Conn fraction II was able to bind [³H]folate.

Key Words:

• Folate
• binding constant of to albumin
• folate
• binding of exogenous in plasma
• gel filtration
• steady state