Uronic Acid Pathway


The uronic acid pathway is a metabolic pathway that converts glucose to various products, such as glucuronic acid, ascorbic acid, and pentoses. It is also known as the glucuronic acid pathway or the hexuronate pathway. The uronic acid pathway is mainly active in the liver and adipose tissue, where it plays important roles in detoxification, biosynthesis, and antioxidant defense.

The uronic acid pathway is different from the main pathways of glucose metabolism, such as glycolysis and the pentose phosphate pathway, in several ways. First, it does not produce any ATP or NADPH, but rather consumes them. Second, it involves unusual sugar intermediates, such as UDP-glucuronate and L-gulonate, that are not found in other pathways. Third, it is regulated by the availability of certain drugs and hormones that affect its enzyme activities.

The uronic acid pathway consists of several steps that can be divided into two phases: the formation of UDP-glucuronate from glucose 6-phosphate, and the conversion of UDP-glucuronate to various products. The first phase is common to all tissues that express the uronic acid pathway, while the second phase varies depending on the tissue type and the physiological condition. The main products of the uronic acid pathway are:

  • Glucuronic acid: a sugar acid that can be conjugated to various substances, such as steroids, bilirubin, and drugs, to make them more soluble and easier to excrete in the bile or urine.
  • Ascorbic acid: also known as vitamin C, a water-soluble antioxidant that is essential for collagen synthesis, wound healing, and immune function. Humans cannot synthesize ascorbic acid because they lack the enzyme L-gulonolactone oxidase.
  • Pentoses: five-carbon sugars that can be used for nucleotide synthesis or interconverted to other sugars by the pentose phosphate pathway.

In this article, we will explore the location, steps, regulation, and significance of the uronic acid pathway in more detail.