Artificial glycosyl phosphorylases.
alpha- and beta-Cyclodextrin 6(A),6(D)-diacids (1 and 2), beta-cyclodextrin-6-monoacid (14), beta-cyclodextrin 6(A),6(D)-di-O-sulfate (16) and beta-cyclodextrin-6-heptasulfate (19) were synthesised. Acids 1, 2 and 14 were made from perbenzylated alpha- or beta-cyclodextrin, by diisobutylaluminum hydride (DIBAL)-promoted debenzylation, oxidation and deprotection. Addition of molecular sieves was found to improve the debenzylation reaction. Sulfates 16 and 19 were made by sulfation of the appropriately partially protected derivatives and deprotection. Catalysis of 4-nitrophenyl glycoside cleavage by these cyclodextrin derivatives was studied. Compounds 1, 2 and 16 were found to catalyse the reaction, with the catalysis following Michaelis-Menten kinetics and depending first order on the phosphate concentration. In a phosphate buffer (0.5 M, 59 degrees C, pH 8.0), K(M) varied from 2-10 mM and the k(cat)/k(uncat) ratio from 80-1000 depending on the stereochemistry of the substrate and the catalyst, with 2 being the best catalyst and with the sulfated 16 also displaying catalytic ability. The monoacid 14 and the heptasulfate 19 were not catalytic.
Department of Chemistry, University of Aarhus, Langelandsgade 140, 8000 Aarhus, Denmark.
Cyril
C
Rousseau
Fernando
F
Ortega-Caballero
Lars Ulrik
LU
Nordstrøm
Brian
B
Christensen
Torben Ellebaek
TE
Petersen
Mikael
M
Bols
D013058:Mass Spectrometry; D019906:Nuclear Magnetic Resonance, Biomolecular; D006005:Phosphorylases / Q000737:chemistry* / Q000378:metabolism; D013379:Substrate Specificity
D006005:Phosphorylases