| 摘要 |
PROBLEM TO BE SOLVED: To obtain the subject new enzyme related to growth and differentiation of cells and tissues, and producing from a sialic acid donor the ganglioside GM3 which is also a precursor of a higher class of gangliosides than itself. SOLUTION: This enzyme is obtained by isolating the cDNA having the base sequence encoding the sialic acid transferase according to the expression cloning method and by cultivating the cells transformed with the cDNA, and is a sialic acid transferase having the following physicochemical properties: (1) capable of selectively forming the ganglioside GM3 by transferring the sialic acid from a sialic acid donor to them-site hydroxyl group of the galactose residue contained in lactosylceramide which is a sialic acid receptor; (2) having an optimal pH of 6.0-7.0; (3) increasing its activity by 1,5 times in the presence of 10 mM of Mn<2+> . |
