1 Departments of Biochemistry and Pediatrics, School of Medicine, University of Southern California and Childrens Hospital of Los Angeles, 4614 Sunset Boulevard Los Angeles, California 90027
The point made by Mellman and Tedesco in their note concerning the effect of dithiothreitol on the UDPG consumption assay for galactose-1-phosphate uridyl transferase is well taken. It adds emphasis to our view on the need to consider the conditions in the assay for interpretation of the findings.
Our hypothesis that low estimates of transferase activity in hemolysates of newborns might be obtained by the UDPG consumption procedure was based on our finding of epimerase activity in hemolysates of newborn infants independent of supplementary NAD.