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The Hopkins-Cole reaction, also known as the glyoxylic acid reaction, is a chemical test used for detecting the presence of tryptophan in proteins. [1] A protein solution is mixed with Hopkins Cole reagent, which consists of glyoxylic acid. Concentrated sulfuric acid is slowly added to form two layers. A purple ring appears between the two ...
The reaction relies on the interaction between glyoxylic acid and the indole ring of the amino acid tryptophan, a structural feature found in most proteins. When proteins are exposed to concentrated sulfuric acid and glyoxylic acid, the indole group undergoes a reaction that produces a highly colored compound.
This acetate, bound to the active thiol group of coenzyme A, enters the citric acid cycle (TCA cycle) where it is fully oxidized to carbon dioxide. This pathway thus allows cells to obtain energy from fat. To use acetate from fat for biosynthesis of carbohydrates, the glyoxylate cycle, whose initial reactions are identical to the TCA cycle, is ...
Glyoxylate and dicarboxylate metabolism describes a variety of reactions involving glyoxylate or dicarboxylates.Glyoxylate is the conjugate base of glyoxylic acid, and within a buffered environment of known pH such as the cell cytoplasm these terms can be used almost interchangeably, as the gain or loss of a hydrogen ion is all that distinguishes them, and this can occur in the aqueous ...
Glyoxylic acid is one of several ketone- and aldehyde-containing carboxylic acids that together are abundant in secondary organic aerosols. In the presence of water and sunlight, glyoxylic acid can undergo photochemical oxidation. Several different reaction pathways can ensue, leading to various other carboxylic acid and aldehyde products. [31]
Glyoxylate reductase uses NAD(P)H to reduce an oxoacid (glyoxylate) to its corresponding α-hydroxy acid (glycolate). This class of reactions provides an opportunity for the synthesis of chiral hydroxy acids. Such products are of interest in the synthesis of pharmaceuticals, such as anti-obesity compounds and semisynthetic penicillins. [13]
The process of bind an amino acid to a tRNA is known as tRNA charging. Here, the enzyme aminoacyl-tRNA-synthetase catalyzes two reactions. In the first one, it attaches an AMP molecule (cleaved from ATP) to the amino acid. The second reaction cleaves the aminoacyl-AMP producing the energy to join the amino acid to the tRNA molecule. [14]
The Gla residues are responsible for the high-affinity binding of calcium ions. [1] [2] The GLA domain binds calcium ions by chelating them between two carboxylic acid residues. These residues are part of a region that starts at the N-terminal extremity of the mature form of Gla proteins, and that ends with a conserved aromatic residue.