Phenylalanine. Phe

Alanine (ala) Phenylalanine (phe) R 1 0 - HNCHC N General formula for an amino acid residue Aspartic Acid (asp)... 

Cleavage occurs with acid. The following tables give relative rate data that are useful for comparing other, more commonly employed, derivatives of phenylalanine (Phe). 

The primary structure of a protein is the sequence of residues in the peptide chain. Aspartame consists of phenylalanine (Phe) and aspartic acid (Asp), and so its primary structure is Phe-Asp. Three fragments of the primary structure of human hemoglobin are... 

Deletion of the phosphate ester oxygen of 1 results in 4-phosphono-phenylalanine, Phe(P03H2) 8 (Scheme 1) which was incorporated in Abl and Src... 

Figure 3.11. Structure of FcyRIIIA and FcyRIIIB. In FcyRIIIA, residue 203 is phenylalanine (Phe), which is followed by a hydrophobic transmembrane domain and a cytoplasmic domain. In FcyRIIIB, residue 203 is serine (Ser), which is followed by a stop codon. See text for details.

Phenylalanine Phe F 2-Amino-3-phenylpropanoic acid CSH6 - C H2 - C H(N H2) - COOH... 

FIGURE 3 Electropherogram of a glutathione (GSH) sample (20mg/ml) containing 1% (w/w) phenylalanine (Phe) as internal standard. (Reprinted with permission from reference 69.)... 

A third type of detector is the intrinsic or native fluorescence detector that utilizes native fluorescence properties of amino acids. The sensitivity of this detector is between UV/PDA and LIF detection. The advantage of this technique over pre-labeling is that there is no pre-labeling step required therefore, the sample preparation is relatively simple, and the sensitivity is improved over UV/LIF. However, the intrinsic fluorescence detection relies on the presence of Tryptophan (Try), Tyrosine (Tyr), Phenylalanine (Phe), and this detector has just become commercially available. 

Aryl side chain containing L-a-amino acids, such as phenylalanine (Phe), tyrosine (Tyr), and tryptophan (Trp), are derived through the shikimate pathway. The enzymatic transformation of phosphoenolpyr-uvate (PEP) and erythro-4-phosphate, through a series of reactions, yields shikimate (Scheme 2). Although shikimate is an important biosynthetic intermediate for a number of secondary metabolites, this chapter only describes the conversion of shikimate to amino acids containing aryl side chains. In the second part of the biosynthesis, shikimate is converted into chorismate by the addition of PEP to the hydroxyl group at the C5 position. Chorismate is then transformed into prephenate by the enzyme chorismate mutase (Scheme 3). 

The less structurally complex members of this group are water soluble, although derivatives of phenylalanine (Phe) are only sparingly soluble. ... 

Phenylalanine (Phe or F) (2-amino-3-phenyl-propanoic acid) is a neutral, aromatic amino acid with the formula HOOCCH(NH2)CH2C6H5. It is classified as nonpolar because of the hydrophobic nature of the benzyl side chain. Tyr and Phe play a significant role not only in protein structure but also as important precursors for thyroid and adrenocortical hormones as well as in the synthesis of neurotransmitters such as dopamine and noradrenaline. The genetic disorder phenylketonuria (PKU) is the inability to metabolize Phe. This is caused by a deficiency of phenylalanine hydroxylase with the result that there is an accumulation of Phe in body fluids. Individuals with this disorder are known as phenylketonurics and must abstain from consumption of Phe. A nonfood source of Phe is the artificial sweetener aspartame (L-aspartyl-L-phenylalanine methyl ester), which is metabolized by the body into several by-products including Phe. The side chain of Phe is immune from side reactions, but during catalytic hydrogenations the aromatic ring can be saturated and converted into a hexahydrophenylalanine residue. ... 

In the simplest case, which is a good starting point—we can always complicate the picture later—a gene specifies the amino acid sequence for one protein. Now we can understand that one three-letter word in the DNA language specifies one amino acid in the protein language. Eor example, the sequence AAA in DNA will be translated into phenylalanine (Phe) in a protein. So a stretch of DNA coded AAAAAAAAAAAA would be translated into Phe-Phe-Phe-Phe, one phenylalanine for each AAA sequence. 

The carbon skeletons of isoleucine (He), phenylalanine (Phe), tyrosine (Tyr), and tryptophan (Trp) are both glucogenic and ketogenic. 

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