Abstract
Studies of alternative substrates of the catalytic monoclonal antibodies 18H4, 7D4, and 45A11 provided us with a better understanding of the mechanism of ester hydrolysis employed by these isoabzymes. The antibodies were studied with analogs of the substrate, phenyl acetate; N-acetylglycine phenyl ester 3 and N-carbobenzoxyglycine phenyl ester 4. All three antibodies catalyzed 3 hydrolysis with kinetic constants similar to those seen with phenyl acetate hydrolysis. However, 4 was found to be a mechanism-based (suicide) inactivator of 18H4 with a kinact of 0.29 min−1 and a K′ of 64 μM. Antibody 18H4 was inactivated by 4 after 3.6 turnovers resulting in the acylation of 1.6 tyrosines per combining site. The data conform to a mechanism in which an inactive O-ZGly-tyrosyl-antibody is formed via a Michaelis complex.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Biochemical and Biophysical Research Communications
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
