Open AccessInhibition of Glucosamine Synthase by Bacilysin and Anticapsin
Author(s) -
Henryk Chmara
Publication year - 1985
Publication title -
microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.019
H-Index - 179
eISSN - 1465-2080
pISSN - 1350-0872
DOI - 10.1099/00221287-131-2-265
Subject(s) - glutamine amidotransferase , glucosamine , glutamine , biochemistry , chemistry , enzyme , atp synthase , substrate (aquarium) , biology , amino acid , ecology
L-Glutamine:D-fructose-6-phosphate amidotransferase ('glucosamine synthase', EC 5.3.1.19) from Escherichia coli MRE 600 was purified at least 75-fold. It catalysed the formation of 21.1 mumol glucosamine 6-phosphate (mg protein)-1 in 30 min at 37 degrees C. Its molecular weight, estimated by gel filtration, was about 90000 and it was inhibited by thiol group reagents. Anticapsin, the C-terminal amino acid of the dipeptide antibiotic bacilysin, and to a lesser extent bacilysin itself, inhibited glucosamine synthase activity. Kinetic studies indicated that the inhibition was non-competitive with respect to fructose 6-phosphate as substrate but partly competitive with respect to L-glutamine. Incubation of the enzyme with anticapsin brought about a time-dependent and irreversible inhibition. It is suggested that anticapsin behaves as a glutamine analogue and that a reaction of its epoxide group with a thiol group of glucosamine synthase results in its linkage to the enzyme by a covalent bond.