Comparison of MBP-6 × His-U24 expression in various E. coli strains, at low (18°C) and high temperature (37°C*). Cultures induced at 18°C (A&B) and 37°C* (C&D) and visualized with His-tag-specific Invision stain (A&C) and Coomassie Blue stain (B&D). Cytoplasmic and periplasmic expressions are denoted by c and p, respectively. While at high temperature (C&D) MBP-6 × His-U24 appears degraded (c lanes) or poorly expressed (p lanes), optimal expression conditions are observed at low temperature especially in the periplasm of C41 (DE3), and cytoplasm of Origami 2 and SHuffle. (*)SHuffle was grown at 30°C, as per vendor's recommendations, perhaps explaining why at this lower temperature some trace full length MBP-6 × His-U24 is observed. Position of full-length MBP-6 × His-U24 (right of the marker lane) is denoted by arrows in A&B, upper arrow in C&D (lower arrows point to truncated/degraded protein). Summary of fold-enhancement for full-length MBP-6 × His-U24 expression at 18°C in the various strains/vectors is listed in E), based on densitometric analysis of bands represented A&B, and normalized against corresponding BL21(DE3) cytoplasmic/periplasmic expression.