Tyrosine chemical structure

To elucidate some enzymatic characteristics of the isolated laccases I, II, and III, substrate specificities for several simple phenols, electrophoresis patterns, ultraviolet spectra, electron spin resonance spectra, copper content, and immunological similarities were investigated. Tyrosine, tannic acid, g c acid, hydroquinone, catechol, pyrogallol, p-cresol, homocatechol, a-naphthol, -naphthol, p-phenylenediamine, and p-benzoquinone as substrates. No differences in the specificities of these substrates was found. The UV spectra for the laccases under stucfy are shown in Figure 4. Laccase III displays three adsorption bands (280, 405, and 600nm), laccase II shows one band 280nm), and laccase I shows two bands (280 and 405 nm). These data appear to indicate differences in chemical structure. The results of the copper content analysis (10) and two-dimensional electrophoresis also indicate that these fractions are completely different proteins (10), Therefore, we may expect differences in substrate specificities between the three laccase fractions for more lignin-like substrates, yet no difference for some simple phenolic substrates. 

The chemical structures of thyroxine and triiodothyronine are shown in Figure 31—1. As shown in the figure, thyroid hormones are synthesized first by adding iodine to residues of the amino acid tyrosine. Addition of one iodine atom creates monoiodotyrosine, and the addition of a second iodine creates diiodotyrosine. Two of these iodinated tyrosines are then combined to complete the thyroid hormone. The combination of a monoiodotyrosine and a diiodotyrosine yields triiodothyronine, and the combination of two diiodoty-rosines yields thyroxine.55... 

Fig. 1. A. Chemical structure of key molecules involved in the key steps in intracerebral synthesis and metabolism of dopamine. The successive steps are regulated by the enzymes tyrosine hydroxylase (TH), aromatic amino acid decarboxylase (AADC), monoamine oxidase (MAO) and dopamine-p-hydroxylase (DBH). B. Structure of key toxins and other drugs acting on dopamine neurones, including 6-hydroxydopamine (6-OHDA), a-methyl tyrosine, and amphetamine. For further details see Iversen and Iversen (1981) or Cooper et al. (1996).

In the 1970s, Hughes et al. were the first to show that two very different chemical structures have similar agonist properties (3). The opioid natural product, morphine (3), was found to resemble the N-terminal structure of the endogenous opioid peptides, enkephalins, (4a) and (4b), and j3-endorphin (5) (Fig. 15.2). The remarkable similarity between the morphine phenol system and the IV-terminal tyrosine residue in the peptide opioids implied that these units reacted with opioid receptors in a similar fashion to elicit comparable responses (4-6). 

Phenylalanine catabolism, 468 chemical structure, 19 plasma conoentralion, 46o sparing by tyrosine, 467,469 Phenylketonuria, 467,469 Phenylpyruvic acid, 469 FhIP,889,B90 Phlebotomy, 759 Phlorizin hydrolase, 109-110 Phorbol esters, cancer and, 916 Phosphatases, 54, 66 Phosphate, 694 in biologLcal fluids, 696 in bore, 697... 

Fig. 6 Chemical structure of maltose-polyrotaxane conjugates consisting of a-CDs, PEG, benzyloxycarbonyl-tyrosine and maltose (Mal-a/E20-TYRZs, 1-3), maltose-a-CD (4), and maltose-poly(acrylic acid) (5) conjugates [14]...

Fig. 8 Cyclic voltammograms (the first three cycles) at 20 mV s of unstirred solutions of a 0.11 mM DEBT in pH 6.5 buffer, and b 3.0 mM tyrosine in pH 6.5 buffer. Insets show the unprotonated amine chemical structures. This figure was reprinted with permission from [70]...

Although phenylalanine and tyrosine are closely related in chemical structure and in mammalian metabolism, these amino acids form separate sections of the Amaryllidaceae alkaloids. Phenylalanine contains no oxygen in the aromatic ring yet it serves as a primary precursor of the C-6—C-1 fragment in alkaloids which may contain as many as three oxygenated substituents in ring A. Tjrosine is a universal precursor of ring C and the two-carbon side chain (Ce—C2). Phenylalanine is not... 

Fales and Pisano (1964) have discussed the gas chromatography of amines, alkaloids, and amino acids. Pollock and Kawauchi (1968) have resolved derivatives of serine, hydroxyproline, tyrosine, and cysteine, as well as racemic aspartic acid and tryptophan. VandenHeuvel and Horning (1964) have listed derivatives of steroids that can be separated. VandenHeuvel et al. (1960) first described the separation of bile acid methyl esters and Sjovall (1964) has extended the methods to bile acids. Gas liquid chromatography (GLC) is useful in the analysis of pesticides, herbicides, and pharmaceuticals (Burchfield and Storrs, 1962). Analysis of alkaloids, steroids, and mixtures of anesthetics and expired air are other examples of the application of this very useful technique. Beroza (1970) has discussed the use of gas chromatography for the determination of the chemical structure of organic compounds at the microgram level. 

Most alkaloids have basic properties coimected with a heterocyclic tertiary nitrogen. Notable exceptions are colchicine, caffeine, and paclitaxel. Most alkaloids are biosynthetically derived from amino acids such as phenylalanine, tyrosine, tryptophan, ornithine, and lysine. Alkaloids represent a wide variety of chemical structures. About 20000 alkaloids are known, most being isolated from plants. But alkaloids have also been found in microorganisms, marine organisms such as algae, dinoflagellates, and puffer fish, and terrestrial animals such as insects, salamanders, and toads. 

Figure 5 Reaction scheme for the preparation of tyrosine-derived polyiminocarbonates. The basic monomeric repeat unit is tyrosyl-tyrosine dipeptidc. To optimize the polymer properties, the chemical structures of the N- and C-terminal protecting groups (Rj and R2) have to be designed carefully. In the first reaction step, protected tyrosyl-tyrosine dipeptide is cyanylated with cyanogen bromide (CNBr). In the next step, polymerization occurs when equimolar quantities of the dipeptide and tlie cyanylated dipeptide are mixed in the presence of a base catalyst.

Ascorbic acid s chemical structure makes it an electron donor and therefore a reducing agent. AA has thus been involved in two different biochemical functions redox/ antioxidant properties and enzymatic cofactor. AA has been demonstrated to be an electron donor for different enzymes. Among these enzymes, three are involved in collagen hydroxylation (Bates et al., 1972 Levene et al., 1972). Two are involved in carnitine synthesis (Nelson et al., 1981 Dunn et al., 1984). The remaining are respectively involved in norepinephrine synthesis (Kuo, 1979) and tyrosine synthesis (La Duand Zannoni, 1964). Deficiency in AA has thus been associated with extracellular matrix defects that are probably involved in vascular problems observed in scurvy. 

Fig. 4.14 NEXAFS C K-edge spectra and chemical structures of the six amino acids gUcyne (Gly), phenilalanine (Phe), histidine (His), tyrosine (Tyr), tryptophane (Trp) and arginine (Arg). (Reprinted from Boese et al. [41], Copyright (2009), with permission from Elsevier)...

In wool and silk fibers, intermolecular bonds are so extensive that the polymers cannot melt. When heated, the primary bonds on the main chains break before all intermolecular bonds can be damaged. As a result, both wool and silk behave like thermosetting polymers. However, the ability for wool and silk fibers to form intermolecular bonds is different. As shown in Table 4.4, the chemical stracture of silk is relatively simple and contains mainly residues of four types of amino acids glycine, alanine, serine, and tyrosine. Wool has a more complex chemical structure and consists of many different types of amino acid residues. As a result, more types of intermolecular bonds can be found in wool fibers. 

However, separation of oL-tyrosine was not achieved. Chemical structure of CDITC is shown in Table 12.3. 

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