ISSN:
1573-1111
Keywords:
Cyclodextrin
;
transacylations
;
metal
;
catalysis
;
ester
;
amide
;
phosphate
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract The ability of cyclodextrins to effect rapid transacylations of bound substrates has been well studied. One important difference between cyclodextrin and enzyme-mediated transacylation is the pH required. Because the pK a of a cyclodextrin secondary-side hydroxyl group is about 12, transacylations are accelerated in the presence of cyclodextrin under basic conditions (pH 〉 10.5). In 1988, our group reported the synthesis of cyclodextrin with attached cyclen-Co(III) complexes; significant acceleration in the reaction withp-nitrophenyl acetate was observed only with the primary side derivative. Of course, metalloenzymes utilize M2+ and not M3+ catalytic centers; in addition, large rate accelerations in the transacylations of both activated and unactivated substrates have been observed previously in systems utilizing M2+ ions (e.g., Zn, Cu, Ni) as well as M3+ ions (e.g. Co, Ir, Cr). In this paper, we describe the ability of βCD-cyclen-M2+ conjugates to transacylate activated esters, amides, and phosphates. In addition, the ability of the apoenzyme mimic to effect transacylations was examined.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01041645
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