Galactose metabolism in transferase-deficient galactosaemic and normal long-term lymphoid cell lines

Summary

The activity (mean±SD) of galactose-1-phosphate uridyl transferase in two long-term lymphoid cell lines from Caucasian patients with transferase deficiency galactosaemia, a heterozygote, and eight normal subjects was 0, 78 and 168±55 nmol UDPG consumed (mg protein)⁻¹h⁻¹, respectively. Also, no activity was found in erythrocytes and cultured fibroblasts from the patients. A small number of cells of the galactosaemic lines cultured in medium, in which galactose was substituted for glucose, survived for 37 days. Normal and galactosaemic lines incubated withD-galactose-[1-¹⁴C] liberated 218.2±65.6 and 18.1 pmol¹⁴CO₂ (mg cellular protein)⁻¹ (6h)⁻¹, respectively. The evolution of¹⁴CO₂ fromD-glucose-[1-¹⁴C] was similar in normal and galactosaemic lines. In the presence of [³H] galactose the radioactivity incorporated into TCA-precipitated material of the galactosaemic lines was 6.8% of the normal lines. Approximately 26% and 1.3% of the total radioactivity was incorporated into molecular species with a molecular weight greater than 400000 daltons in normal and galactosaemic cells, respectively. Similar molecules were identified in the cell-free medium of both normal and deficient cells except for an 18000 daltons molecule identified only in the medium of the normal cells. These findings indicate that a small amount of galactose is metabolized in galactosaemic lines with no transferase activity.