quantification of protein

[AKB]

I know the structure of a protein.  How do I quantify the amount of protein
in a bacterial cell (or the lack thereof).   I don't think you could run a
western blot on it since that would only tell you the presence of the
protein.   I guess you could estimate the mRNA sequence but you couldn't be
sure of a correct radioprobe if the exact sequence isn't known.  Anyway, how
would one approach this problem.  I need to determine if a protein's
production is being inhibited by a specific antibiotic.  This is
hypothetical and not from any specific experiment.