The nucleus will have the greatest mass. Among the 3 kinds of subatomic particles, electrons are the lightest (by several orders of magnitude), protons and neutrons are much closer is magnitude, though neutrons are slightly heavier. However, in the diagram, the nucleus contains both the neutrons and the protons, so its combined mass would be heavier than either the neutrons alone or the protons alone.
At high temperatures the shape of the enzyme is altered so that it is no longer complementary to its specific substrate. This effect can be permanent and irreversible and is called denaturation
