Search results
Results from the WOW.Com Content Network
Biliverdin results from the breakdown of the heme moiety of hemoglobin in erythrocytes. Macrophages break down senescent erythrocytes and break the heme down into biliverdin along with hemosiderin, in which biliverdin normally rapidly reduces to free bilirubin. [1] [3] Biliverdin is seen briefly in some bruises as a green color.
The production of biliverdin from heme is the first major step in the catabolic pathway, after which the enzyme biliverdin reductase performs the second step, producing bilirubin from biliverdin. [5] [6] Ultimately, bilirubin is broken down within the body, and its metabolites excreted through bile and urine; elevated levels may indicate ...
In the human liver, bile is composed of 97–98% water, 0.7% bile salts, 0.2% bilirubin, 0.51% fats (cholesterol, fatty acids, and lecithin), and 200 meq/L inorganic salts. [2] [3] The two main pigments of bile are bilirubin, which is orange-yellow, and its oxidised form biliverdin, which is green.
Biliverdin reductase (BVR) is an enzyme (EC 1.3.1.24) found in all tissues under normal conditions, but especially in reticulo-macrophages of the liver and spleen. BVR facilitates the conversion of biliverdin to bilirubin via the reduction of a double bond between the second and third pyrrole ring into a single bond.
The next step is the reduction of biliverdin to a yellow color tetrapyrrole pigment called bilirubin by cytosolic enzyme biliverdin reductase. This bilirubin is "unconjugated", "free", or "indirect" bilirubin. Around 4 mg of bilirubin per kg of blood are produced each day. [31]
This reaction can occur in virtually every cell; the classic example is the formation of a contusion, which forms different chromogens as it gradually heals: (red) heme to (green) biliverdin to (yellow) bilirubin. In terms of molecular mechanisms, the enzyme facilitates the intramolecular hydroxylation of one meso carbon centre in the heme.
Get AOL Mail for FREE! Manage your email like never before with travel, photo & document views. Personalize your inbox with themes & tabs. You've Got Mail!
In human metabolism, bilirubin is a breakdown product of heme. A modified bilane is an intermediate in the biosynthesis and uroporphyrinogen III from porphobilinogen . Examples of bilins are found in animals (cardinal examples are bilirubin and biliverdin ), and phycocyanobilin , the chromophore of the photosynthetic pigment phycocyanin , in ...