Catalytic Antibodies Induced by a Zwitterionic Hapten

• Published in: Chemistry : a European journal Vol. 7; no. 17; pp. 3748 - 3755
• Main Authors: Tsumuraya, Takeshi, Takazawa, Nobuo, Tsunakawa, Atsuko, Fleck, Roman, Masamune, Satoru
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag GmbH 03-09-2001; WILEY‐VCH Verlag GmbH
• Subjects: Amides - metabolism; Animals; Antibodies, Catalytic - biosynthesis; Antibodies, Catalytic - chemistry; Binding Sites, Antibody; catalytic antibodies; Esters - metabolism; haptens; Haptens - administration & dosage; Haptens - immunology; Hydrolysis; immunochemistry; Ions; Kinetics; Mice; Models, Chemical; Structure-Activity Relationship; transition states
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/1521-3765(20010903)7:17<3748::AID-CHEM3748>3.0.CO;2-G

A zwitterionic hapten 4 featuring both positively and negatively charged functional groups was designed and synthesized with the goal of generating catalytic antibodies for the hydrolysis of ester 6 and amide 7. Of the 36 monoclonal antibodies specific to BSA–4 (bovine serum albumin) that were isolated, six accelerated the hydrolysis of 6. Two catalytic antibodies with distinctively different and representative kinetic behaviors were selected for detailed kinetic studies. Whereas H8‐2‐6F11 showed burst kinetic behavior, which can be attributed to the formation of an acyl intermediate, H8‐1‐2D5 did not, but it did exhibit high multiple turnover activity. The rate of hydrolysis of 6 catalyzed by H8‐1‐2D5 followed Michaelis–Menten kinetics; the apparent values of the Michaelis–Menten constant Km and the catalytic constant kcat were 488 μM and 3.5 min−1, respectively. The catalytic rate enhancement (kcat/kun) observed for H8‐1‐2D5 was 1.3×105, which is approximately two orders of magnitude greater than those for monofunctional haptens. Thus H8‐1‐2D5 compares well in catalytic activity with antibodies isolated by a related approach called heterologous immunization.
A zwitterionic hapten (1) featuring both positively and negatively charged functional groups was synthesized with the goal of generating catalytic antibodies for the hydrolysis of ester 2 and amide 3. The catalytic rate enhancement elicited against 1 (kcat/kun = 1.3×105) is approximately two orders of magnitude greater for H8‐1‐2D5 than for monofunctional haptens. This catalytic activity compares well with that for antibodies isolated by the related approach of heterologous immunization.