Why is it so that enzymes become totally non-functional after maximum temperature?
For the ability of enzyme to function, certain distant amino acids should appear close to each other due to proper folding. Proper folding is achived by fomration of multiple weak bonds between distant parts of the protein. High temperature destroys these bonds, and enzyme becomes a chain of amino acids. The ones, which should be close to each other to perform the certain process, are now distant. Thus, the enzyme cannot perform catalysis.