Folic acid binding by human plasma albumin

Area of Science:

• Biochemistry
• Pharmacology

Background:

• Folate is essential for cellular processes.
• Understanding folate binding proteins is crucial for drug delivery and nutrient absorption.

Purpose of the Study:

• To investigate the binding characteristics of [3H]folate to human plasma albumin.
• To determine the binding sites, affinity, and physiological relevance of this interaction.

Main Methods:

• Sephadex G-200 gel filtration in a steady-state system.
• Analysis of [3H]folate binding to pure human albumin and normal human plasma.

Main Results:

• Two binding sites for [3H]folate were identified per albumin molecule with an equilibrium constant of 0.9x10(3) 1/mol.
• Albumin was the primary binder of exogenous [3H]folate in normal plasma.
• At plasma concentrations below 10(-5) mol/l, 50% of folate was free and 50% was albumin-bound.
• Optimal binding occurred around pH 6, with minimal binding at pH values above 8 or below 4.5.
• Transferrin and Cohn fraction II did not bind [3H]folate.

Conclusions:

• Human plasma albumin exhibits specific binding of folate.
• Albumin plays a significant role in folate transport and availability in blood.
• The pH dependency suggests physiological regulation of folate binding to albumin.