Difference between revisions of "Part:BBa K3515001"

Revision as of 14:23, 25 May 2020

K coil alpha helix with cysteine to be used with a E coil alpha helix for protein immobilization.

The K coil alpha helix is made of five-heptad repeats which work in conjunction with the E coil alpha helices five-heptad repeats. The E heptad and K heptad contain sequences of EVSALEK and KVSALKE, respectively, where the hydrophobic residues leucine and valine form a hydrophobic interface, stabilizing the coiled coil heterodimeric structure. This hydrophobic effect is further amplified by repetition of the heptad repeat and provides great stability. Glutamate and lysine at the outer positions of the coils form electrostatic interactions further stabilizing the heterodimer structure. Addition of a cysteine to the C- termini of either alpha helix provides a method of protein immobilization. One coils cysteine may bind a surface such as gold on the inside of a biosensor, while another coils cysteine can bind a proteins cysteine residue. The alpha helices may then associate, and a protein can therefore be immobilized. This method of protein immobilization is cost effective and simple compared to existing biochemical techniques. Immobilizing proteins to a biosensor, such as a phosphate binding protein with a fluorophore pair may allow for metabolite detection.

Cartoon structure of the five-heptad repeated alpha helix coil. Figure generated using PyMOL structure. Predicted structure was generated using the Phyre2 protein fold recognition server.

E coil interacting with the K coil to form a stable coiled coil structure. 3D representation used to show the interaction between heptad repeats and the hydrophilic core. Cysteine residues are in red. Figure generated using PyMOL software.

Chao, H., Bautista, D.L., Litowski, J., Irvin, R.T. and Hodges, R.S., 1998. Use of a heterodimeric coiled-coil system for biosensor application and affinity purification. Journal of Chromatography B: Biomedical Sciences and Applications, 715(1), pp.307-329.

Sequence and Features