 Hi, I'm Sally. I'm a third-year PhD student at the Australian National University and I work on an enzyme called rubisco So enzymes are biological catalysts. They work to allow reactions to happen under biological conditions and a lot of different things affect how Enzyme functions and how well it functions Enzymes are biological catalysts usually made of proteins that allow reactions to occur under biological conditions a number of factors will affect the rate at which and how well enzymes work and Most enzymes are specifically adapted to work in a very limited range of conditions Temperatures can have massive effects on enzymes if you consider warm-blooded organisms like people the cellular environment in which enzymes operate is constantly maintained at 37 degrees Celsius For many enzymes if they get too hot the bonds that hold the proteins together in their secondary and tertiary structures break and the enzymes lose their shape This is called denaturing and when that happens they can no longer perform chemical reactions Chemical reactions in biology are still chemical reactions And this means the energy in the form of heat makes them go faster at low temperatures There isn't much energy and things move slowly reactions go more slowly This means that for enzymes the fastest rate is usually an Optimization between a temperature at which it's warm enough for the substrates and the enzyme to be moving about But cool enough that the enzyme still maintains its tertiary structure and Because most enzymes are made of proteins, they're sensitive to the same things that proteins are sensitive to So proteins are made up of amino acids and each of the 20 amino acids differs by the side chains That those amino acids have and some of these side chains are sensitive to pH They might change their shape or their charge at different pH's This means or this has a flow-on effect to the rest of the protein and can result in differences in the way that protein functions Enzyme activity can also be altered by the presence of other compounds in the solution. It's working in