Remarkable supramolecular catalysis of glycoside hydrolysis by a cyclodextrin cyanohydrin.
(6AR,6DR)-6A,6D-di-C-cyano-beta-cyclodextrin (3) was synthesized and shown to catalyze hydrolysis of nitrophenyl glycosides with the reaction following Michaelis-Menten kinetics. At pH 7.4 and 25 degrees C, hydrolysis of 4-nitrophenyl-beta-glucopyranoside (2) was catalyzed with KM = 15 mM, kcat = 8.2 x 10-6 s-1, and kcat/kuncat = 1217. Catalysis was observed with concentration of 3 as low as 10 muM. Hydrolysis of the corresponding alpha-glucoside, alpha-galactoside, alpha-mannoside, and 2-nitrophenyl-beta-galactoside was also catalyzed by 3, with kcat/kuncat ranging from 283 to 2147. A series of analogues of 3 was prepared and investigated for catalysis of the hydrolysis of 2: (6AR,6DR)-6A,6D-di-C-propyl-beta-cyclodextrin (9) was not catalytic, while 6A,6D-di-C-cyano-6A,6D-dideoxy-beta-cyclodextrin (12) had a low catalytic activity (kcat/kuncat = 4). A kcat/kuncat = 48 was found for 6A,6D-dialdehydo-beta-cyclodextrin dihydrate (11). It was proposed that 3 acts by general acid catalysis on the bound substrate.
Ortega-Caballero
Fernando
F
Department of Chemistry, University of Aarhus, DK-8000, Denmark.
Rousseau
Cyril
C
Christensen
Brian
B
Petersen
Torben Elleaek
TE
Bols
Mikael
M
D040761:Biomimetic Materials / Q000138:chemical synthesis / Q000737:chemistry; D002384:Catalysis; D003505:Cyclodextrins / Q000138:chemical synthesis / Q000737:chemistry*; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000378:metabolism; D006027:Glycosides / Q000737:chemistry* / Q000378:metabolism; D006868:Hydrolysis; D007700:Kinetics; D009570:Nitriles / Q000138:chemical synthesis / Q000737:chemistry*
D003505:Cyclodextrins; D006027:Glycosides; D009570:Nitriles; C430593:cyanohydrin; D006026:Glycoside Hydrolases