Anomeric preference of glucose utilization in rat erythrocytes

Abstract

The beta-anomer of glucose relative to the alpha-anomer was more rapidly metabolized into lactate by rat erythrocytes at 37 degrees C (beta/alpha ratio = ca. 1.3): the amounts of alpha- and beta-D-glucose metabolized into lactate during 3 min were 0.21 and 0.27 mumol/gHb, respectively. Also, the transport of beta-D-glucose into erythrocytes was more rapid than that of alpha-D-glucose: the amounts of alpha- and beta-D-glucose transported into erythrocytes during 3 min were approximately 3.5 and 5.0 mumol/gHb, respectively. Glucose phosphorylation by rat erythrocyte hexokinase (i.e., a possible rate-limiting step in glycolysis) occurred at higher velocities with the beta-anomer than with the alpha-anomer (beta/alpha ratio = 1.28). The Km value of hexokinase for either anomer of glucose was 53 microM. The glucose concentrations in erythrocytes incubated with alpha- and beta-D-glucose reached about 1 mM in 1 min, indicating that hexokinase is almost completely saturated with glucose within less than 1 min. The results suggest that glucose phosphorylation and glucose transport are major and minor determinants, respectively, for the anomeric preference of glucose utilization in rat erythrocytes.

Understanding Conformational Dynamics of Complex Lipid Mixtures Relevant to Biology

“…It also may account for the finding that the β - d -glucose anomer is transported more rapidly than the -anomer via GLUT1 (Duan et al. 1992), the reason being that β - d -glucose has a lower enthalpy barrier than α - d -glucose to reach the conformation where the radius is minimal (puckered skew boat) (Mayes et al. 2014).…”