A quantitative and comprehensive investigation of enzyme reactions within cells is published online in this week's Nature Chemical Biology. The findings provide the groundwork to ask more specific questions about how cells interact with their natural environment and how they control their own metabolism.
Cellular metabolism includes the creation and consumption of small molecules, or metabolites, that are used in creating proteins, the cell membrane, and in many other biological processes. The reactions for these biological processes are facilitated by enzymes.
Metabolites are often studied by determining relative concentrations of various molecules ― the amount of one compound in comparison to another. Joshua Rabinowitz and colleagues used several metabolomic analysis tools to determine the absolute concentration, or the specific amount of compounds in cells independent of any other molecules. By comparing these concentrations to a database of known enzyme parameters, the scientists were able to tell which of the cell's molecules are constantly being used in reactions, and which are likely being used to respond to other factors such as whether the cell is actively growing, or under attack.