Variations in riboflavin binding by human plasma: identification of immunoglobulins as the major proteins responsible

Journal Article · Tue Oct 01 00:00:00 EDT 1985 · Biochem. Med.; (United States)

DOI:https://doi.org/10.1016/0006-2944(85)90106-1· OSTI ID:5944083

Innis, W S; McCormick, D B; Merrill, Jr, A H

Riboflavin binding by plasma proteins from healthy human subjects was examined by equilibrium dialysis using a physiological concentration of (2-14C)riboflavin (0.04 microM). Binding ranged from 0.080 to 0.917 pmole of riboflavin/mg of protein (with a mean +/- SD of 0.274 +/- 0.206), which corresponded to 4.14 to 49.4 pmole/ml of plasma (15.5 +/- 11.0) (N = 34). Males and females yielded similar results. Upon fractionation of plasma by gel filtration, the major riboflavin-binding components eluted with albumin and gamma-globulins. Albumin was purified and found to bind riboflavin only very weakly (Kd = 3.8 to 10.4 mM), although FMN and photochemical degradation products (e.g., lumiflavine and lumichrome) were more tightly bound. Binding in the gamma-globulin fraction was attributed to IgG and IGA because the binding protein(s) and immunoglobulins copurified using various methods were removed by treatment of plasma with protein A-agarose, and were coincident upon immunoelectrophoresis followed by autoradiography to detect (2-14C)riboflavin. Differences among the plasma samples correlated with the binding recovered with the immunoglobulins. Binding was not directly related to the total IgG or IgA levels of subjects. Hence, it appears that the binding is due to a subfraction of these proteins. These findings suggest that riboflavin-binding immunoglobulins are a major cause of variations in riboflavin binding in human circulation, and may therefore affect the utilization of this micronutrient.

• Research Organization: Emory Univ. School of Medicine, Atlanta, GA
• OSTI ID: 5944083
• Journal Information: Biochem. Med.; (United States), Vol. 2
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
RIBOFLAVIN
AUTORADIOGRAPHY
CHEMICAL BONDS
BLOOD PLASMA
CARBON 14 COMPOUNDS
IMMUNOGLOBULINS
MAN
PHOTOCHEMISTRY
RECEPTORS
SPECTROPHOTOMETRY
ANIMALS
BIOLOGICAL MATERIALS
BLOOD
BODY FLUIDS
CHEMISTRY
GLOBULINS
LABELLED COMPOUNDS
MAMMALS
MATERIALS
MEMBRANE PROTEINS
ORGANIC COMPOUNDS
PRIMATES
PROTEINS
VERTEBRATES
VITAMIN B GROUP
VITAMINS
550201* - Biochemistry- Tracer Techniques