Figure 1.

Inducible peptide expression. (A) Analysis of total cellular proteins from E. coli DH5αPRO cells. Mid-log phase E. coli cells harboring pC³868 (encoding GST, lanes 1–4) or pC³844 (encoding Pro-3/GST, lanes 5–8) were induced with 0 (lanes 1 and 5), 10 (lanes 2 and 6), 50 (lanes 3 and 7), or 250 (lanes 4 and 8) ng/ml aTc. Total cellular proteins were separated by 4–20% SDS/PAGE and stained with Coomassie Brilliant Blue. (B) Glutathione/Sepharose affinity resin purification of GST proteins. Lane 1, GST purified from cells carrying pC³868; lane 2, Pro-3/GST purified from cells carrying pC³844; lanes 3 and 4, pC³844 resin extract washed with 10 or 100 μM prolyl-adenylate analog during purification; lane 5, pC³844 resin extract washed with 100 μM isoleucyl-adenylate analog; lane 6, purified E. coli ProRS.