Catalytically Distinct Antibodies Prepared by the Reactive Immunization versus Transition State Analogue Hapten Manifolds

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• 作者：Anita Datta ; Paul Wentworth ; Jr. ; Joanne P. Shaw ; Anton Simeonov ; and Kim D. Janda
• 刊名：Journal of the American Chemical Society
• 出版年：1999
• 出版时间：November 17, 1999
• 年：1999
• 卷：121
• 期：45
• 页码：10461 - 10467
• 全文大小：120K
• 年卷期：v.121,no.45(November 17, 1999)
• ISSN：1520-5126

文摘

This report describes the first direct comparison between the reactive immunization and transitionstate analogue hapten manifolds for catalytic antibody production. In an initial communication (Janda et al J.Am. Chem. Soc. 1997, 119, 10251) we described the use of a phosphonate diester hapten 5, in a reactiveimmunization approach, that elicited a panel of proficient biocatalysts for the hydrolysis of S-(+)-naproxenp-methylsulfonylphenyl ester (3b) [k_cat(3b)/k_uncat(3b) = 0.05-6.60 × 10⁵]. However, only moderateenantioselectivity was obtained when the panel of antibody catalysts was studied in a kinetic resolution ofrac-3a, the best result leading to S-(+)-4a in 90% ee for 35% conversion of rac-3a. This report details atransition state analogue hapten approach to elicit antibody catalysts for this same process by employment ofphosphonate monoester 6. This strategy has yielded a library of catalysts with excellent turnover numbers[k_cat(3b)/k_uncat(3b) = 0.14-19.0 × 10⁵] and enantioselectivities. Three of these catalysts, 6G6, 12C8, and12D9, perform a useful kinetic resolution of rac-3a, generating S-(+)-naproxen 4a in >98% ee with up to50% conversion. Comparing the two hapten strategies reveals that the antibodies, although elicited for thesame reaction with the same substrate, exhibit quite different catalytic behavior. The transition state analogueapproach has furnished better catalysts, in terms of turnover numbers and enantiomeric discrimination, butwhich possess varying degrees of product inhibition by phenol 9. Thermodynamic evaluation reveals thattheir catalytic power is derived almost entirely as a function of differential stabilization of the transition stateover the ground state: K_m(3b)/K_i(8). By contrast, the reactive immunization approach has elicited more proficientbiocatalysts that couple an efficient "catalytic" mechanism and improved substrate recognition with no productinhibition.