Substrate structure governs maximum rate of catalysis exerted by cyclodextrin oxidase chemzymes

TY - JOUR

T1 - Substrate structure governs maximum rate of catalysis exerted by cyclodextrin oxidase chemzymes

AU - Bjerre, Jeannette

AU - Bols, Mikael

PY - 2011/4

Y1 - 2011/4

N2 - Selectively modified α-and β-cyclodextrin ketones or aldehydes act as artificial oxidases on a variety of small lipophilic substrates. The structure of the substrate is a highly important factor governing how effectively the oxidation reaction can be catalyzed. Amino acid-type substrates were not prone to catalysis, which yields new information about the limits of CD catalysis. Aniline showed some non-quantifiable catalysis, but for quinones and benzyl alcohols no net catalysis was detected. For aminophenol oxidation, o-aminophenols are far better substrates than p-aminophenols. The CD-catalyzed reaction follows Michaelis-Menten kinetics, involves CD cavity binding of the substrate and substrate recognition, and thus encompasses many of the hallmarks of natural enzymatic catalysis. Strong binding of the cooxidant H 2O2 to the CD catalytic carbonyl group is a prerequisite for the subsequent oxidation of the substrate and in accordance with this, the binding of H2O2 to β-CD dialdehyde was shown to be strong (Kd = 1.4 mM). β-CD 6A,6D-diketone which binds H2O2 weaker than an aldehyde was accordingly a less efficient oxidase. The wide range of substrates applicable to CD chemzyme catalysis brings about optimism for future scopes of synthetic biology.

AB - Selectively modified α-and β-cyclodextrin ketones or aldehydes act as artificial oxidases on a variety of small lipophilic substrates. The structure of the substrate is a highly important factor governing how effectively the oxidation reaction can be catalyzed. Amino acid-type substrates were not prone to catalysis, which yields new information about the limits of CD catalysis. Aniline showed some non-quantifiable catalysis, but for quinones and benzyl alcohols no net catalysis was detected. For aminophenol oxidation, o-aminophenols are far better substrates than p-aminophenols. The CD-catalyzed reaction follows Michaelis-Menten kinetics, involves CD cavity binding of the substrate and substrate recognition, and thus encompasses many of the hallmarks of natural enzymatic catalysis. Strong binding of the cooxidant H 2O2 to the CD catalytic carbonyl group is a prerequisite for the subsequent oxidation of the substrate and in accordance with this, the binding of H2O2 to β-CD dialdehyde was shown to be strong (Kd = 1.4 mM). β-CD 6A,6D-diketone which binds H2O2 weaker than an aldehyde was accordingly a less efficient oxidase. The wide range of substrates applicable to CD chemzyme catalysis brings about optimism for future scopes of synthetic biology.

M3 - Journal article

SN - 1388-3127

VL - 69

SP - 417

EP - 423

JO - Journal of Inclusion Phenomena and Macrocyclic Chemistry

JF - Journal of Inclusion Phenomena and Macrocyclic Chemistry

IS - 3-4

ER -