A type I beta-turn in green fluorescent protein (GFP) was engineered to a foreign loop. Molecular dynamics simulation study showed that the addition of foreign loop into GFP did not have a negative influence on the conformation stability of GFP structure, but the GFP variant with the foreign loop sequence was completely misfolded in real folding conditions. The co-incorporation of the enhancing mutations for GFP folding made it possible to generate a foldable and active GFP variant with the foreign loop sequence, although the folding efficiency and specific activity of the GFP were negatively affected by the introduced loop.

Protein engineering, Turn and loop, Folding and misfolding, Green fluorescent protein