Nav: Home

New insight into enzyme evolution

March 03, 2016

How enzymes - the biological proteins that act as catalysts and help complex reactions occur - are 'tuned' to work at a particular temperature is described in new research from groups in New Zealand and the UK, including the University of Bristol.

Professor Vic Arcus (University of Waikato) and colleagues, including Bristol's Professor Adrian Mulholland and Dr Marc van der Kamp, showed that the heat capacity of enzymes changes during a reaction as the enzymes tighten up. Exactly how much the enzymes tighten up is the critical factor in determining the temperature at which they work best. These findings could provide a route to designing better biocatalysts for use in chemical reactions in industrial processes, such as the production of drugs.

Enzymes have an optimum temperature at which they are most catalytically active. Above that temperature, they become less active. Previously, it was thought that this was because enzymes unfolded (lost their functional shape) at higher temperatures, but actually they typically become less active at higher temperatures even though they maintain their functional shape.

So what makes them less active? And what is it that causes enzymes from different organisms to have different catalytic activities at the same temperature? Enzymes from organisms that live at normal temperatures are not very active at low temperatures, while cold-adapted enzymes are active in the cold - why, when they have very similar structures?

The new research, published as a 'New Concept' in Biochemistry (and selected for the American Chemical Society (ACS) Editors' Choice), shows that a basic physical property - the heat capacity - explains and predicts the temperature dependence of enzymes. The heat capacity of a substance is the amount of heat required to raise its temperature by one degree. For enzymes, the heat capacity changes during the reaction and this change is 'tuned' to give the optimal temperature.

Professor Mulholland said: "Our theory - macromolecular rate theory, (MMRT) - applies to all enzymes, and so will have a critical role in predicting metabolic activity as a function of temperature.

"We also expect to see characteristics of MMRT at the level of cells, whole organisms and even ecosystems. This means that it is important in understanding and predicting the response of biological systems to temperature changes, for example, how ecosystems will respond to temperature changes associated with climate change."

The theory also explains why enzymes are so big (the more 'difficult' the chemistry to catalyse, the bigger the enzyme). It also hints at why proteins were eventually preferred by evolution over nucleic acids as catalysts in biology: proteins offer much more ability to 'tune' dynamics and their response to chemical reactions.
-end-
Paper

'On the Temperature Dependence of Enzyme-catalyzed Rates' by Vickery L. Arcus, Erica J. Prentice, Joanne K. Hobbs, Adrian J. Mulholland, Marc W. Van der Kamp, Christopher R. Pudney, Emily J. Parker and Louis A. Schipper in Biochemistry

University of Bristol

Related Proteins Articles:

Discovering, counting, cataloguing proteins
Scientists describe a well-defined mitochondrial proteome in baker's yeast.
Interrogating proteins
Scientists from the University of Bristol have designed a new protein structure, and are using it to understand how protein structures are stabilized.
Ancient proteins studied in detail
How did protein interactions arise and how have they developed?
What can we learn from dinosaur proteins?
Researchers recently confirmed it is possible to extract proteins from 80-million-year-old dinosaur bones.
Relocation of proteins with a new nanobody tool
Researchers at the Biozentrum of the University of Basel have developed a new method by which proteins can be transported to a new location in a cell.
More Proteins News and Proteins Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Teaching For Better Humans
More than test scores or good grades — what do kids need to prepare them for the future? This hour, guest host Manoush Zomorodi and TED speakers explore how to help children grow into better humans, in and out of the classroom. Guests include educators Olympia Della Flora and Liz Kleinrock, psychologist Thomas Curran, and writer Jacqueline Woodson.
Now Playing: Science for the People

#535 Superior
Apologies for the delay getting this week's episode out! A technical glitch slowed us down, but all is once again well. This week, we look at the often troubling intertwining of science and race: its long history, its ability to persist even during periods of disrepute, and the current forms it takes as it resurfaces, leveraging the internet and nationalism to buoy itself. We speak with Angela Saini, independent journalist and author of the new book "Superior: The Return of Race Science", about where race science went and how it's coming back.