Adenine, adenosine from

As indicated in Fig. 25-18, free adenine released from catabolism of nucleic acids can be deaminated hydrolytically to hypoxanthine, and guanine can be deaminated to xanthine.328 The molybdenum-containing xanthine oxidase (Chapter 16) oxidizes hypoxanthine to xanthine and the latter on to uric acid. Some Clostridia convert purine or hypoxanthine to xanthine by the action of a selenium-containing purine hydroxylase.3283 Another reaction of xanthine occurring in some plants is conversion to the trimethylated derivative caffeine. 328b One of the physiological effects of caffeine in animals is inhibition of pyrimidine synthesis.329 However, the effect most sought by coffee drinkers may be an increase in blood pressure caused by occupancy of adenosine receptors by caffeine.330... 

Figure 16.1 The structure of adenosine triphosphate (ATP). The lower ring is a ribose sugar, the upper molecule is the base, adenine. Adenosine diphosphate (ADP) differs from ATP by having two phosphate groups attached instead of three.

Figure 1 Influence of pH on migration times of purine compounds. Conditions capillary, 44 cm (37 cm to detector) x 75 pm i.d. buffer, 20 mM borate voltage, 20 kV temperature, 37°C detection, UV, 254 nm. Key = adenine, + = adenosine, = guanine, x=guanosine, = hypoxanthine, A=xanthine, X = uric acid. (Reprinted from Ref. 1 3 with permission of Elsevier Science Publishers.)...

Jacobson MA. In BellardineUi, L., Pelleg, A., Eds. Adenosine and Adenine Nucleotides From Molecular Biology to Integrative Physiology Kluwer Norwell, 1995 5-13. 

Jacobson MA. In Belardinelli L, Pelleg A, eds. Adenosine and adenine nucleotides from molecular biology to integrative physiology. Boston Kluwer, 1995 5-13... 

Significantly, ESI-MS investigations showed that 107 recognized adenine and adenosine from other nucleotides and nucleobases. The interaction of 107 with nucleotides and nucleobases was also indicated by surface pressure area isotherms at the air-water interface and the respective complexes were formed in the monolayer (2008CJC170). 

Uracil, uridine, adenine, adenosine and guanine have been identified in the roots (147). Choline was isolated from the roots as the reineckate in 0.55% yield (148) and a-pyrrolidone was identified by GLC analysis (149). 

The formation of radioactive adenosine from labelled adenine nucleotides, revealed by the addition of the unlabelled nucleoside to the hepatocyte suspension, as well as the reassessment of the activity of the cytoplasmic 5 -nucleotidase in physiological conditions, raised the possibility that adenosine may be continuously formed from adenine nucleotides in basal conditions but not contribute to the production of allantoin because of its reutilization by adenosine kinase. This futile cycle would explain our previous observation that the production of allantoin by isolated hepatocytes is not influenced by coformycin at a concentration that inhibits selectively adenosine deaminase (Van den Berghe et al., 1980). The arrest of the reutilization of adenosine would cause an irreversible loss of adenine nucleotides under the form of this nucleoside, that would be further degraded to allantoin. 

Scheme 12.100. A synthesis of adenosine from adenine (after Vorbrtlggen, H. Kroiikiewicz, K. Bennua, B. Chem. Ber., 1981,114,1234). A version of the Hiibert-Johnson reaction.

These reactions lead to a synthesis of cozymase or flavine -adenine dinucleotide from adenosine triphosphate with nicotinamide-ribofuranoside-5-phosphoric acid or riboflavine phosphate respectively. 

Similar to the nucleobase-calixarene cmijugates described above, Shi et al. designed a caUx[4]arene derivative with a uracil moiety at the upper rim by coupling uracil acetic acid directly to a mono-anilino caUx[4]arene. The obtained It—A isotherms again indicate the formation of supramolecular complexes at the air-water interface, that rely on the base pairing between uracil and adenine moieties. Furthermore ESl-MS experiments showed that the uracil calixarene conjugate is able to recognize adenine and adenosine from other nucleotides and bases [36],... 

Though in this system also the products of inactivation of cozymase have not been determined chemically, the ability of components of the cozymase molecule to serve as precursors of the substance has been demonstrated. Cozymase production by yeast in aqueous suspension at 25°C. for some 22 hours was markedly increased by added adenine, adenosine, or nicotinic acid, and still further by mixtures of these or by glucose. Kinetic experiments comparing the production of cozymase from such substances with production from the unknown products of inactivation were not reported, results quoted (58) referring to cozymase extracted from the cells at one time only but the rates of production are unlikely to differ greatly. The spontaneous reactivation at 25° was at a rate of about 2.5 m/xM per... 

Riboflavin-5 -Adenosine Diphosphate. Riboflavin-5 -adenosine diphosphate [146-14-5] (flavin—adenine dinucleotide, FAD), C27H33N9O15P2 (2), mol wt 785.56, was first isolated in 1938 from the D-amino acid oxidase as its prosthetic group (95), where it was postulated to be... 

---