Anomeric specificity ofd-glucose metabolism in rat brain cells

Rat brain cells were incubated at 9 °C (and occasionally at 37°C) in the presence of the anomers ofd-[5-³H]glucose,d-[U-¹⁴C]glucose,d-[6-¹⁴C]glucose andd-[1-¹⁴C]glucose (1.0 mM). The utilization of β-d-[5-³H]glucose was slightly higher than that of α-d-[5-³H]glucose, a situation possibly attributable to the anomeric behaviour of hexokinase. However, the production of¹⁴CO₂ from the α-anomer always largely exceeded that from the β-anomer. The anomeric difference ind-[U-¹⁴C]glucose oxidation, relative tod-[5-³H]glucose utilization, was suppressed in the presence of NH₄Cl. Even at anomeric equilibrium, the relative contribution of α-d-glucose to¹⁴CO₂ output exceeded its relative abundance. The β/α ratio ford-[1-¹⁴C]glucose oxidation (ord-[U-¹⁴C]glucose oxidation) was higher than that ford-[6-¹⁴C]glucose oxidation. Comparable observations were made in brain cells from albino rats and either lean or obese Zucker rats. It is concluded thatd-glucose metabolism displays anomeric specificity in rat brain cells, even when the latter are exposed to equilibratedd-glucose. It is also speculated that anomeric differences in the phosphorylation ofd-glucose by bound hexokinase may directly influence mitochondrial oxidative events.