Scientists shed light on controversial theory of protein structure

February 13, 2015, University of Bristol
Scientists shed light on controversial theory of protein structure
Helix macropole. Credit: Dr Emily Baker

A team of chemists, biochemists and mathematicians at the University of Bristol have published a paper in the journal Nature Chemical Biology, which explores how protein structures are stabilised.

There are many forces that hold together the three-dimensional, functional structures of proteins. Despite considerable effort, understanding of these forces is still quite rudimentary. The research from the Bristol team aimed to dissect out some of these forces by reducing the complexity of the problem.

Proteins are chains of linked together by so-called amide bonds. These chains respond to water to fold up into their preferred 3D structures. One of the substructures in the hierarchy of folded proteins is called the a-helix. It is this simpler structure that the researchers focused on.

Dr Emily Baker conducted the research in the laboratory of Professor Dek Woolfson. She explains: 'The amide bonds can be thought of as tiny bar magnets. When an a-helix is formed these all line up. For almost 40 years it was thought that the smaller bar magnets, which are known as dipoles, add up to give one large effective magnet, called the helix macrodipole.'

This macrodipole, which results in overall positive and negative charges at the ends of the helix, has been used to explain many observations in , stability and function. However, the Bristol team's precise experiments on fragments of proteins that form a-helices, but without the complications of the rest of the , show that the effects of the helix macrodipole are imperceptible compared with local effects between other charged atoms in the molecule.

As Professor Woolfson puts it: 'We are not saying that the helix macrodipole doesn't exist, it is just that it is very weak and its influence is far less than previously thought. Indeed, it is trumped by the local effects that we studied. In short, we do not need to use the macrodipole concept anymore to explain the vast majority of phenomena that have been attributed to it in the past, including in textbooks.'

Explore further: New protein structure expands nature's repertoire of biomolecules

More information: "Local and macroscopic electrostatic interactions in single α-helices." Nature Chemical Biology (2015) DOI: 10.1038/nchembio.1739

Related Stories

Researchers create designer 'barrel' proteins

October 23, 2014

Proteins are long linear molecules that fold up to form well-defined 3D shapes. These 3D molecular architectures are essential for biological functions such as the elasticity of skin, the digestion of food, and the transport ...

Fundamental forces in protein structure revisited

July 12, 2010

( -- Research scientists from Bristol have joined forces with colleagues from America to unravel one of the fundamental problems of molecular biology, paving the way for better engineering of biological systems.

Researchers discover key to cell specialization

November 10, 2011

Researchers at then Albert Einstein College of Medicine of Yeshiva University have uncovered a mechanism that governs how cells become specialized during development. Their findings could have implications for human health ...

Cell: Protein folding via charge zippers

January 18, 2013

Membrane proteins are the "molecular machines" in biological cell envelopes. They control diverse processes, such as the transport of molecules across the lipid membrane, signal transduction, and photosynthesis. Their shape, ...

Recommended for you


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.