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L-Serine (left) and D-serine (right) in zwitterionic form at neutral pH. This compound is one of the proteinogenic amino acids. Only the L-stereoisomer appears naturally in proteins. It is not essential to the human diet, since it is synthesized in the body from other metabolites, including glycine.
In enzymology, a serine O-acetyltransferase (EC 2.3.1.30) is an enzyme that catalyzes the chemical reaction. acetyl-CoA + L-serine CoA + O-acetyl-L-serine Thus, the two substrates of this enzyme are acetyl-CoA and L-serine, whereas its two products are CoA and O-acetyl-L-serine.
In microorganisms and plants, the enzyme serine acetyltransferase catalyzes the transfer of acetyl group from acetyl-CoA onto L-serine to yield O-acetyl-L-serine. [39] The following reaction step, catalyzed by the enzyme O-acetyl serine (thiol) lyase, replaces the acetyl group of O-acetyl-L-serine with sulfide to yield cysteine. [40]
Serine dehydratase has also been found to be absent in human colon carcinoma and rat sarcoma. The observed enzyme imbalance in these tumors shows that an increased capacity for the synthesis of serine is coupled to its utilization for nucleotide biosynthesis as a part of the commitment to cellular replication in cancer cells.
3-Phosphoglycerate dehydrogenase catalyzes the transition of 3-phosphoglycerate into 3-phosphohydroxypyruvate, which is the committed step in the phosphorylated pathway of L-serine biosynthesis. It is also essential in cysteine and glycine synthesis, which lie further downstream. [7]
Reactions beginning with either one or two molecules of pyruvate lead to the synthesis of alanine, valine, and leucine. Feedback inhibition of final products is the main method of inhibition, and, in E. coli , the ilvEDA operon also plays a part in this regulation.
Serine protease, as released by mast cells, is an important diagnostic marker for type 1 hypersensitivity reactions e.g., anaphylaxis. More useful than histamine due to the longer half-life , meaning it remains in the system for a clinically useful length of time.
In enzymology, a serine-pyruvate transaminase (EC 2.6.1.51) is an enzyme that catalyzes the chemical reaction. L-serine + pyruvate 3-hydroxypyruvate + L-alanine. Thus, the two substrates of this enzyme are L-serine and pyruvate, whereas its two products are 3-hydroxypyruvate and L-alanine.