BINDING OF A HIGH-ENERGY SUBSTRATE CONFORMER IN ANTIBODY CATALYSIS

被引:36
作者
CAMPBELL, AP
TARASOW, TM
MASSEFSKI, W
WRIGHT, PE
HILVERT, D
机构
[1] Scripps Res Inst, DEPT CHEM, 10666 N TORREY PINES RD, LA JOLLA, CA 92037 USA
[2] SCRIPPS RES INST, DEPT MOLEC BIOL, LA JOLLA, CA 92037 USA
关键词
D O I
10.1073/pnas.90.18.8663
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
Enzymes can substantially increase the probability of a reaction by exploiting binding energy to preorganize their substrates into reactive conformations. Similar effects are likely to be important in a wide variety of designed catalysts, including catalytic antibodies. Transferred nuclear Overhauser effects have been used here to investigate how an antibody possessing chorismate mutase activity binds its flexible substrate molecule chorismate. The conversion of chorismate to prephenate by way of a Claisen rearrangement requires the substrate to adopt an energetically disfavored diaxial conformation in which the enolpyruvyl side chain is positioned over the six-membered ring. The antibody, which was elicited by a conformationally restricted transition state analog for this reaction, appears to bind this high-energy substrate conformer preferentially, as judged by diagnostic intramolecular transferred nuclear Overhauser effects. Inhibitor studies with the transition state analog confirm that preorganization takes place exclusively at the antibody active site. These results thus provide strong physical evidence for a direct relationship between the properties of a catalytic antibody and the structure of the transition state analog originally used to elicit the immune response.
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页码:8663 / 8667
页数:5
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