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Revision as of 20:44, 20 October 2013
GLucCaM contains ten cysteine residues. Since our protein could not be deactivated with calcium, we considered the possibility of disulfide bonds forming across the protein, preventing conformation changes. Unfortunately, we do not know the specific amino acids responsible for the disulfide bonds, so we selected a reasonable set of four cysteine residues highlighted in yellow below. The light blue indicates the two halves of GLuc, the red indicates calmodulin, and the green regions indicates the two linkers.
Another possibility we explored was varying the linker length and rigidity. The original GLucCam structure has amino acid strands GGGGT and GGGS as the first and second linker sequence. We explored the following linker variations:
All linker variations showed a decrease in luminescence level, but they all exhibited significant decrease in activity when exposed to high concentration of calcium. Unfortunately, the protein switch does not respond to increased levels of M13, but this is a promising start for continued modification to the output domain.