The use of specific indicator enzymes to characterize the nature of radioactive peaks, obtained from paper chromatograms of protein-free cell filtrates from cell cultures briefly incubated with [Wlgalactose, has been described. The use of an internal standard ([3H]UDPgalactose) added to the filtrates before their exposure to the indicator enzymes illustrates the specificity of the method used, as well as its usefulness in quantitative analysis of the abundance of nucleotide sugars in cell cultures under different culture conditions.
Varying types of complex forms of galac-about new biochemical methods becoming tose play an important role in the develop-available to biologists at large. This detailed ment of mammalian cells. Free exogenous survey of chromatographic and enzymatic galactose is taken up by mammalian cells methods and their combination we hope will in culture and accumulated as metabolic serve this purpose. It is dedicated to Dr. products of the UDP-hexose pathway ( l-4).
Nason's memory and to his life work. If NIL hamster cell cultures maintained in standard culture media (glucose concentra-' This paper is dedicated to the memory of Dr. a-D-galactose l-phosphate; UDPG dehy, UDPglucose: