Enhanced production of human full-length immunoglobulin G1 in the periplasm of Escherichia coli. 
Monoclonal antibodies are currently the most important pharmaceutical proteins, and the economic production of functional immunoglobulin G (IgG) is an important issue in biotechnology.  Recent successes in the development of aglycosylated IgG variants that do not require glycosylation for effector functions have increased the use of Escherichia coli as an alternative host for economic production of IgG, instead of traditional mammalian host expression systems.  Here, we have developed a new E. coli host-vector system for the high-level production of full-length IgG1 by examining (1) E. coli strains, (2) modification of 5' untranslated region sequences, and (3) co-expression of periplasmic foldase.  With the engineered host-vector system, fed-batch cultivations were conducted at two different conditions, and under optimized conditions, up to 362 mg/L of full-length IgG1 could be produced in a relatively short-time (22 h) cultivation.  The fully assembled IgG1 from fed-batch cultivation was purified with high purity and yield.  With the purified IgG1, the specific bindings to an antigen, anthrax toxin PA, and to human neonatal Fc receptor were successfully demonstrated.