Castanospermine, a tetrahydroxylated alkaloid that inhibits beta-glucosidase and beta-glucocerebrosidase
1983
Saul, R. | Chambers, J.P. | Molyneux, R.J. | Elbein, A.D.
Castanospermine (1,6,7,8-tetrahydroxyoctahydroindolizine) was tested against a variety of commercially available glycosidases and found to be a potent inhibitor of almond emulsin β-glucosidase, and also to inhibit fungal β-xylosidase. This alkaloid was inactive on yeast α-glucosidase, α- or β-galactosidase, α-mannosidase, β-N-acetylhexosaminidase, β-glucuronidase, α-L -fucosidase. Fifty-percent inhibition of β-glucosidase required about 10 μg/ml of castanospermine. The amount of inhibition was uniform throughout the time course, and the inhibition with regard to substrate concentration (p-nitrophenyl-β-D -glucopyranoside) appeared to be of the mixed type. Castanospermine was also a potent inhibitor of β-glucocerebrosidase when assayed with fibroblast extracts using either a fluorimetric or a radioactive assay. Interestingly enough, castanospermine also inhibited the lysosomal α-glucosidase, and this inhibition required comparable levels of alkaloid to that required for inhibition of β-glucocerebrosidase. However, a number of other lysosomal glycosidases were not sensitive to castanospermine (i.e., α- or β-galactosidase, α- or β-mannosidase, α- or β-L -fucosidase, β-N-acetylhexosaminidase, β-glucuronidase).
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