Thursday, 5 February 2015

Cracking Protein Folding : Unboiling of an egg



At the first instance, the scientific accomplishment of getting egg protein back intact after boiling or unboiling the egg in short might sound silly and foolish accomplishment. But the seemingly frivolous task of retrieving protein in its original form is the most daunting task. Protein biologists struggle with mind boggling and finicky protein extraction protocols to obtain a functional protein in purest form but the protein becomes unusable as its gets entangled with itself or gets stuck with the containers and instruments during experimentation. Thus significant amount of precious protein is lost. This technique besides revitalising the protein holds the key for cracking the protein folding problem too. It offers a magical solution for refolding the proteins into its original shape.


Proteins are quintessential and the most indispensable tools for working in biological and chemical laboratories. In vivo protein synthesis is carried out ribosomes dictated by the genetic code. Basically proteins are made of amino acids that contain carbon, hydrogen, nitrogen, and sulphur oxygen. Functionality or the efficiency of proteins is determined by the unique nature of folding of proteins. More often the nature of bonding (hydrophilic –water loving or hydrophobic- water hating) between the molecules in the protein determines the shape and activity of the proteins. Proteins in their native state have lowest energy and are most stable.  

Scientists during the course of biological or chemical research lose significant portion of precious proteins as they get stuck to containers, instruments or get entangled with each other becoming unusable. Most often these proteins couldn’t be salvaged easily. Existing techniques are tedious, time consuming and even the amounts of protein retrieved is too low. Scientists at the University of Irvine have claimed to have discovered a technique which can help in untangling the protein and allow them to return to their original conformation.

Gregory Weiss’s lab using a vortex fluid device untangled proteins from the boiled egg. The vortex fluid device was used by an Australian lab to peel sheets of carbon of few atoms thickness from graphene. The device spins molecules in liquid state and spins them through an open- ended test tube. The liquid spreads out as a thin layer of few microns (one millionth of meter) thickness. The forces in the rapidly spinning tube transfer energy to the molecules, separating them in a controlled way. Weiss contemplated on using the machine for revitalising proteins. Egg white is watery containing several proteins besides lysozyme. Upon heating structural bonds between proteins are broken, thus they lose their native conformation and become a thick clump of solid mass. Now, scientists tried to recover lysozyme by dissolving the egg white in a solution that breaks the clumps overnight. After a day the solution becomes clear, full of unfolded proteins.

Refolding is the biggest task to restore the functionality of protein. Solution of unfolded proteins is whirled through the vortex fluid machine wherein proteins spread out as thin layer separated from its neighbour thus allowing the proteins to refold without tangling. By fine-tuning the speed and rotation of the vortex, scientists can generate the force strong enough to separate protein molecules apart from each other and gentle enough to allow them to refold into their natural shapes.  Scientists first used this technique to restore a protein from Escherichia coli, protein kinase A (PKA) three times larger than lysozyme. They slightly modified the protocol to refold the protein. They managed to manipulate the protein into refolding by hinging one end of protein onto a large bead (Ni+2charged immobilised metal affinity chromatography). This in fact is similar to the process by which proteins are folded naturally by the ribosomes.

The force requirement for different protein would vary and subsequently the protocol should be effectively reconstructed to suit to the needs. Scientists are now aiming to build a large-scale vortex machine and exploring the possibility of using different solutions, level of forces and settings suited for different proteins. This method has the ability to transform the production of proteins. Pharmaceutical companies have started creating cancer antibodies in expensive hamster ovary cells which often don’t fold properly and a misfolded protein is not functional. This technique could be of great help to pharmaceutical and biotechnology industries that work on recombinant proteins. It can aid in untangling over expressed proteins that are jettisoned into inclusion bodies as complex aggregates.

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