A polyclonal monospecific serum which coats the protein surface with antibody will normally inhibit all protein functions, but a monoclonal antibody, which binds away from the active site need not have any detectable effect at all (Burstin et al., 1982; Massey and Schochetman, 1981; Pinter et al., 1982; Thorpe et al., 1982) .