Which of the following is associated with enzymes?

An enzyme is a biological catalyst that can significantly increase the rate of a biochemical reaction without being used up in the process. 

Enzymes are a group of complex proteins. However, not all proteins (like structural and transport proteins) have enzymatic properties. Only catalytic proteins are called enzymes. Some enzymes have only one protein, while other enzymes may contain multiple proteins.

There are different types of enzymes that work in the body of an organism to carry out vital functions such as digestion and energy production. E.g.  Helicases are enzymes that can unwind a DNA strand while Ligases are groups of enzymes that join two separate molecules or strands of DNA.