Biosynthesis of galactogen: identification of a beta-(1----6)-D-galactosyltransferase in Helix pomatia albumen glands.
A beta-(1----6)-D-galactosyltransferase has been purified over 2000-fold by affinity chromatography on UDP-p-aminophenyl-Sepharose. The enzyme, from a pellet fraction (8000 x g) of Helix pomatia albumen gland, catalyzes transfer of D-galactose from UDP-galactose to a (1----6) linkage on acceptor H. pomatia galactogen. Three other polymers served as acceptors: beef lung galactan, Lymnaea stagnalis galactogen and arabinogalactan from larch wood. To determine the linkage specificity of the enzyme, it was incubated with UDP-D-galactose and acceptor galactogen that had been tritiated previously by treatment with galactose oxidase and [3H]KBH4. The [3H]galactogen reaction product was recovered, methylated, hydrolyzed and acetylated; tritiated derivatives were identified by mass spectroscopy of effluent fractions separated by gas chromatography. This analysis revealed that (1----6)-linked galactosyl groups had been added to the enzyme-treated acceptor galactogen. Also identified was a hydrolytic enzyme that removed terminal alpha 1,2-linked L-galactosyl residues from H. pomatia galactogen.
Goudsmit
E M
EM
Department of Biological Sciences, Oakland University, Rochester, MI 48309-4401.
Ketchum
P A
PA
Grossens
M K
MK
Blake
D A
DA
D000818:Animals; D002846:Chromatography, Affinity; D002851:Chromatography, High Pressure Liquid; D005685:Galactans / Q000096:biosynthesis*; D005700:Galactosyltransferases / Q000302:isolation & purification / Q000378:metabolism*; D006372:Helix, Snails / Q000201:enzymology*; D007700:Kinetics; D008970:Molecular Weight; D012627:Sebaceous Glands / Q000201:enzymology; D013379:Substrate Specificity
D005685:Galactans; C007812:galactogen; D005700:Galactosyltransferases; C061142:UDP-beta(1-6)-D-galactosyltransferase