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The urea cycle converts highly toxic ammonia to urea for excretion. [1] This cycle was the first metabolic cycle to be discovered by Hans Krebs and Kurt Henseleit in 1932, [2] [3] [4] five years before the discovery of the TCA cycle. The urea cycle was described in more detail later on by Ratner and Cohen.
For more information see urea cycle. Pages in category "Urea cycle" The following 21 pages are in this category, out of 21 total.
The function of fumarase in the citric acid cycle is to facilitate a transition step in the production of energy in the form of NADH. [12] In the cytosol, the enzyme functions to metabolize fumarate, which is a byproduct of the urea cycle as well as amino acid catabolism. Studies have revealed that the active site is composed of amino acid ...
The organic compound citrulline is an α-amino acid. [2] Its name is derived from citrullus, the Latin word for watermelon.Although named and described by gastroenterologists since the late 19th century, it was first isolated from watermelon in 1914 by Japanese researchers Yatarō Koga (古賀彌太郎) and Ryō Ōtake (大嶽了) [3] [4] and further codified by Mitsunori Wada of Tokyo ...
He found that citrulline acted as a catalyst in the metabolic reactions of urea from ammonia and carbon dioxide. He and Henseleit published their discovery in 1932. Thus the urea cycle (or "ornithine cycle") was established, and it was the first metabolic cycle to be discovered. [20] [31]
The structure of the molecule of urea is O=C(−NH 2) 2.The urea molecule is planar when in a solid crystal because of sp 2 hybridization of the N orbitals. [8] [9] It is non-planar with C 2 symmetry when in the gas phase [10] or in aqueous solution, [9] with C–N–H and H–N–H bond angles that are intermediate between the trigonal planar angle of 120° and the tetrahedral angle of 109.5°.
Diagram of biochemical urea cycle. Uses only capital letters, no textual description. 16:16, 5 February 2006: 800 × 600 (80 KB) Ayacop: Diagram of biochemical urea cycle. Uses only capital letters, no textual description. 16:09, 5 February 2006: 800 × 600 (80 KB) Ayacop: Diagram of biochemical urea cycle. Uses only capital letters, no textual ...
In mammalian cells, urea is the chief end-product of nitrogen catabolism and plays an important role in the urinary concentration mechanism. Thus, the plasma membrane of erythrocytes and some renal epithelial cells exhibit an elevated urea permeability that is mediated by highly selective urea transporters.