Workflow Developed to Analyze Complex Enzyme Structures

A new method has enabled the natural structure of particularly large and complex enzymes to be revealed. Scientists at Martin Luther University Halle-Wittenberg (MLU) and TU Berlin published their findings in Cell Reports. 

"Up until now, the enzyme complex has always been broken down into its individual parts before being examined. Studying the entire, functional complex is very complicated," says lead researcher Panagiotis Kastritis. To solve this problem, his team combined various biochemical and biophysical methods of investigation.

In addition to using mass spectrometry and chemical analyses, they used cryo-electron microscopy to examine the structures. Their method enables complex, organic structures to be observed at a high resolution and in their natural state. "However, it is very important to subsequently bring together all this data in computer models," says Kastritis. 

The combination of methods allowed the researchers to gain an insight into how the various subunits of the enzyme complex interact with each other and have also discovered that it functions differently than previously assumed. "It was previously thought that all of the subunits were directly involved in the reaction," says Kastritis. "But now we know that some of them seem to form a kind of chamber that protects the reaction." Because the complexes are very similar across organisms, the results are also helping researchers understand the human pyruvate dehydrogenase complex.

"If we are able to better understand the natural structure, we will be able to recognise tiny changes and understand why the reaction is no longer occurring as it should," says Kastritis.