511 GALACTOSE METABOLISM IN GALACTOSEMIC LYMPHOID LINES

The activity (mean ± SD) of galactose-l-phosphate uridyl transferase in two lymphold lines from two patients with galactosemia, a heterozygote, and eight normal subjects was 0, 78, and 168 ± 55 umoles UDPG consumed/mg protein/hr, respectively. Absence of enzyme activity also was found in RBC and skin fibroblasts of the galactosemic (glc) patient The glc lines failed to grow in medium in which galactose was substituted for glucose. No difference in the total radioactivity present in the cells was found between normal, glc, and heterozygous lines cultured in the presence of (3H)-galactose. The radioactivity incorporated into TCA-precipiated cellular material of the glc lines was 6.9% (3.5 × 103 CPM/mg protein/hr) of the normal (51.4 × 03) and heterozygous (49.6 × 103) lines. Normal and glc lines pcubated with (14C)-l-galactose produced 218 ± 66 and 18 pmole 14CO2/mg cellular protein/6hrs, respectively. The production of 14CO2 from (14C)-1-glucose was similar in normal and glc lines. Most of the radio-activity in normal cells was incorporated into molecular species with MW> 400,000. The glc cells did incorporate a small amount of radioactivity into macromolecules. Similar molecules were identified in the cell-free medium of both normal and deficient cells. In addition, a molecular form with MW<25,000 was released in the medium of the normal cells but not of the glc cells. These findings indicate that a small amount of galactose is metabolized in glc lines even in the apparent absence of enzyme activity. Furthermore, these lines are suitable for studying galactose metabolism and treatment of patients with galactosemia.