Journal of Neuroscience, Vol 5, 2874-2881, Copyright © 1985 by Society for Neuroscience
Immunological uniqueness of human monoamine oxidases A and B: new evidence from studies with monoclonal antibodies to human monoamine oxidase A
LM Kochersperger, A Waguespack, JC Patterson, CC Hsieh, W Weyler, JI Salach and RM Denney
Monoamine oxidase (EC 1.4.3.4; MAO) is the primary enzyme responsible for
the intraneuronal degradation of biogenic amines in the central nervous
system. An understanding of the physiological significance of the
functional and regulatory differences between the two forms of the enzyme,
MAOs A and B, would be facilitated by the availability of antibodies
specific for the two forms of the enzyme. We previously isolated and
characterized a monoclonal antibody (MAO B-1C2, previously designated
MAO-1C2) which binds human MAO B but not A. We describe here four new
monoclonal antibodies (designated MAO A-3C9, A-4F10, A-7B10, and A-7E10)
which were elicited to highly purified MAO A from human placenta and which,
in the presence of antimouse IgG and Staphylococcus aureus,
immunoprecipitate greater than 90% of the catalytically active purified MAO
A. MAO A-3C9 appears to have a lower affinity for purified MAO A than the
other three antibodies and does not immunoprecipitate either MAO A or MAO B
from human platelets or from Triton X-100 extracts of human placental and
liver mitochondria. MAO A-4F10, A-7B10, and A-7E10 immunoprecipitate
catalytically active MAO A from Triton X- 100 extracts of human placental
and liver mitochondria, but not catalytically active MAO B from either
pletelets or from Triton X-100 extracts of human liver mitochondria.
Collectively, these anti-MAO monoclonal antibodies reveal unique epitopes
on human MAO A not shared by MAO B, and at least one epitope on MAO B not
shared by MAO A. These immunochemical differences support the hypothesis
that MAO A and MAO B are different proteins, presumably isozymes.