Aspartate amino acid family

PAL/TAL both belong to the L-amino acid ammonia lyase family, which catalyzes the formation of various a,/3-unsaturated acids by elimination of ammonia (ammonium ion) from the corresponding L-ct-amino acids. This family of proteins includes aspartate ammonia lyase (AAL), methylaspartate ammonia lyase (MAL), HAL,... 

Mammals, fungi, and higher plants produce a family of proteolytic enzymes known as aspartic proteases. These enzymes are active at acidic (or sometimes neutral) pH, and each possesses two aspartic acid residues at the active site. Aspartic proteases carry out a variety of functions (Table 16.3), including digestion pepsin and ehymosin), lysosomal protein degradation eathepsin D and E), and regulation of blood pressure renin is an aspartic protease involved in the production of an otensin, a hormone that stimulates smooth muscle contraction and reduces excretion of salts and fluid). The aspartic proteases display a variety of substrate specificities, but normally they are most active in the cleavage of peptide bonds between two hydrophobic amino acid residues. The preferred substrates of pepsin, for example, contain aromatic residues on both sides of the peptide bond to be cleaved. 

V-methyl-D-aspartate (NMDA) receptors have multiple regulatory sites. To date, three NMDA receptor subunit families have been identified, one represented by a single gene (NR1, encoding a protein of -900 amino acids), the... 

Amino Acid Biosynthesis Aromatic amino acid family Aspartate family Glutamate family Pyruvate family Serine family Histidine family Other... 

In addition to the 0-methylation of aspartate and glutamate residues, the C-terminal carboxyl group of GTPases are methylated. In the G-protein family C-terminal cysteines are prenylated at the sequence CZZX, where Z is a hydrophobic amino acid and X represents any residue. Once the ZZX sequence is cleaved by a special protease, the isoprenylcysteine carboxymethyltransferase (Icmt) methylates the C-terminal carboxyl group and effectively creates a more hydrophobic enzyme. ... 

Non-essential amino acids are those that arise by transamination from 2-oxoacids in the intermediary metabolism. These belong to the glutamate family (Glu, Gin, Pro, Arg, derived from 2-oxoglutarate), the aspartate family (only Asp and Asn in this group, derived from oxaloacetate), and alanine, which can be formed by transamination from pyruvate. The amino acids in the serine family (Ser, Gly, Cys) and histidine, which arise from intermediates of glycolysis, can also be synthesized by the human body. 

This zinc-dependent enzyme [EC 3.4.17.1], a member of the peptidase family M14, catalyzes the hydrolysis of peptide bonds at the C-terminus of polypeptides. Little hydrolytic action occurs if the C-terminal amino acid is aspartate, glutamate, arginine, lysine, or proline. Car-boxypeptidase A is formed from a precursor protein, procarboxypeptidase A. 

Although L-phenylalanine is a protein amino acid, and is known as a protein acid type of alkaloid precursor, its real role in biosynthesis (providing C and N atoms) only relates to carbon atoms. L-phenylalanine is a part of magic 20 (a term deployed by Crick in his discussion of the genetic code) and just for this reason should also be listed as a protein amino acid type of alkaloid precursor, although its duty in alkaloid synthesis is not the same as other protein amino acids. However, in relation to magic 20 it is necessary to observe that only part of these amino acids are well-known alkaloid precursors. They are formed from only two amino acid families Histidine and Aromatic and the Aspartate family . 

Sulfate Must Be Reduced to Sulfide before Incorporation into Amino Acids The Aspartate and Pyruvate Families Both Make Contributions to the Synthesis of Isoleucine... 

The aspartate (oxaloacetate) family of amino acids includes aspartate, asparagine, methionine, lysine, threonine, and isoleucine (see fig. 21.1). The pyruvate family includes alanine, valine, leucine, and also lysine and isoleucine (see fig. 21.1). Threonine is a precursor of isoleucine. It is converted into isoleucine by a group of enzymes that are also used in the synthesis of valine (fig. 21.10). 

The aspartate and pyruvate families together contain 11 amino acids. Because of the reactions involved in its synthesis, isoleucine is considered a member of both families. Isoleucine and valine use four enzymes in common in their biosynthetic pathways. 

In brain tissue, low concentrations of glutamate and aspartate perform as neurotransmitters, but at high concentration these amino acids act as neurotoxins. Major advances in the excitatory amino acid receptor field have come from the identification, characterization, and cloning of different families of receptors and transporters (Dingledine and McBain, 1999). These receptors and transporters are specialized... 

---