Suicide-substrate inactivation of beta-galactosidase by diazomethyl beta-D-galactopyranosyl ketone.
Diazomethyl beta-D-galactopyranosyl ketone (1) has been proven to be a mechanism-based, irreversible (suicide-substrate) inactivator of Aspergillus oryzae beta-D-galactosidase, but not an inactivator of E. coli lacZ beta-D-galactosidase. Compound 1 is stable in buffers of normal physiological pH. It is decomposed by H+, but not by nucleophiles. Inactivation of A. oryzae beta-D-galactopyranosyl ketone (2) nor diazomethyl alpha-D-galactopyranosyl ketone inactivated the enzyme and therefore inactivation is stereospecific, excess inhibitor could be separated from inactive enzyme without regain of activity and therefore it is bound irreversibly, and a second pulse of enzyme is inactivated at the same rate as enzyme inactivated to 95% activity by the first pulse. Diazomethyl beta-D-glucopyranosyl ketone (2) inhibited sweet almond beta-D-glucosidase.
BeMiller
J N
JN
Whistler Center for Carbohydrate Research, Purdue University, West Lafayette, Indiana 47907.
Gilson
R J
RJ
Myers
R W
RW
Santoro
M M
MM
D001236:Aspergillus oryzae / Q000201:enzymology; D002384:Catalysis; D003978:Diazomethane / Q000031:analogs & derivatives* / Q000737:chemistry; D005690:Galactose / Q000031:analogs & derivatives* / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet; D013379:Substrate Specificity; D001616:beta-Galactosidase / Q000037:antagonists & inhibitors*
C054623:diazomethylgalactopyranosyl ketone; D003978:Diazomethane; D001616:beta-Galactosidase; D005690:Galactose