Hexokinase & Glucose

Glucose is rich in energy. The bonds that hold glucose together are carbon, hydrogen and oxygen, and when these bonds are broken, energy can be released. Hexokinase is an enzyme, a protein catalyst, that starts the process of energy release from glucose.

Glucose the Energy Molecule

• Catalyst pellets for cars and enzymes for molecules are each catalysts.

  Glucose is one of the simplest and most basic sugars known. Green plants manufacture energy-rich glucose from water and carbon dioxide, as well as starches, that are important to human nutrition, health and energy needs. Animals, when they ingest plants and associated glucose, can extract the potential energy from the glucose by first adding chemical energy to glucose. The enzyme used for this first step is hexokinase.

Hekokinase Is a Protein Catalyst

• Spinach leaves use light energy to make sugar from carbon dioxide and water.

  Almost all enzymes are protein catalysts. Proteins are made of specific kinds and arrangements of amino acids. This gives each enzyme unique features or characteristics. One enzyme usually does just one reaction over and over again. An enzyme is not used up in the reaction, and the enzyme can perform the same task many thousands of times in a fraction of a second. What the enzyme works on is termed its "substrate." Hexokinase is an specific enzyme that has glucose as its substrate.

Hexokinase Enzyme Adds Phosphate to Glucose

• Road or path to energy extraction begins with hexokinase.

  Hexokinase does one thing to glucose--it adds a phosphate that it takes from one of the many surrounding ATP molecules in the cytoplasm of the cell. The hexokinase literally brings glucose sugar molecules together with ATP molecules and attaches one phosphate onto each glucose molecule. The ATP (adenosine triphosphate) now becomes ADP (adenosine diphosphate), with one less phosphate molecule than ATP.

Hexokinase Energizes Glucose

• Wine production begins with sugar, yeasts and their hexokinases.

  Hexokinase adds a phosphate to glucose and energizes the glucose. This glucose is known as glucose-6-phosphate because the phosphate has been added to the carbon number 6 of glucose. This energized glucose is the very first step on the path to energy extraction via the glycolytic pathway, or glycolysis. The road to energy extraction is a multistep process that next involves the addition of one more phosphate by a different enzyme.

Energy and Wine Production Each Begin with Hexokinase

• Almost every organism known has hexokinase. Organisms make ATP energy by degrading glucose, and the waste end products of carbon dioxide and water are used by plants in photosynthesis to make more sugar. Incomplete metabolism of glucose in many animals yields lactic acid, and this molecule fatigues muscles. Yeasts convert glucose and other sugars into alcohol. Hexokinase enzymes work every second of every day to supply energy and keep living cells alive.