Explain the relationship between a proteins structure and its ability to function

Proteins such as enzymes have active sites that are complementary to that of the shape of the substrates, allowing chemical reactions to occur. However, high temperatures causes the hydrogen bonds in the protein to break down, change structure and lose its active site. Hence, the three-dimensional shape of the protein is no longer complementary to that of the substrate and no enzyme-substrate is form, resulting in no chrmical reactions to occur.