Hexokinase is an enzyme that plays a crucial role in the metabolism of glucose, the primary energy source for cells. It catalyzes the first step of glycolysis, converting glucose into glucose-6-phosphate. This reaction is essential for trapping glucose inside the cell and initiating its breakdown for energy production. There are several isoforms of hexokinase, each with different properties and tissue distributions. For example, hexokinase I is found in most tissues, while hexokinase IV, also known as glucokinase, is primarily present in the liver and pancreas. These variations allow for the regulation of glucose levels in the body.