2-Amino adenosine

The phosphorylation of adenosine to adenosine-5 -phosphate was demonstrated some time ago in crude yeast extracts. The extracts did not act on guanosine, and no yeast adenylic acid was formed. More recently it has been found that the synthesis involves transfer of phosphate from ATP to adenosine, and the term adenosine phosphoki-nasc has been applied to the enzyme. The activity occurs in yeast maceration juice and in kidney and liver extracts of the rat and rabbit. The enzyme is quite specific, for a partially purified brewers yeast preparation catalyzes the phosphorylation of only two nucleosides out of seventeen which have been tested. The two nucleosides are adenosine itself and 2,6-diaminopurine riboside (2-amino adenosine). The reactions are ... 

Two useful derivatives whose syntheses are not described here are the 2 -<7-allylinosine monomer (13,14), and the 2 -6 -allyl-2-amino-adenosine monomer (13,14). The 2 -0-allylinosine monomer is obtained from compound 12 by desilylation, oximate reaction (requires 24 h reflux in acetonitrile), and dimethoxytritylation followed by phosphitylation. The 2 -0-allyl-2-aminoadenosine monomer is obtained from compound 20 by protection of the exocyclic ammo groups followed by desilylation, dimethoxytritylation, and finally phosphitylation. 

Fig. 8. Rephcation. The amino adenosine X and the pentafluorophenyl ester Y form a hydrogen-bonded dimer XY, prior to reaction between the amine and the activated ester groups (shown in the circle). The reaction product is a <7 -amide conformer cis-Z that isomeri2es to the more stable trans- acnide Z. The rephcative process is cataly2ed by the reaction product Z (also referred to as the template). First, a termolecular complex XYZ is formed from X, Y, and Z.

Ci2H18N706P 4 H20 8-[(2-Aminoethyl)amino]adenosine 3, 5 -phosphate, tetra- AEADMP 38 519... 

Cytidine 2, 3 -cyclicphosphate, polymeric complexes of Cd" and Cu" and cytidine 5 -phosphate, l-(j8-D-arabinofuranosyl)cytosine Pt complex. Adenosine complexed with 5-bromouracil, iS-methyl-5 -thioadenosine, 2, 3 -0-isopropyIideneadenosine, 2, 3 -0-(2-carboxyethyl)ethylideneadeno-sine, the amino-acid adenosine derivatives (5) and (6) which are constitutents of tRNA, 8-[(2-aminoethyl)amino]adenosine 3, 5 -cyclic phosphate. 8-Iodoguanosine, 2-JV-methylguanosine, a guanosine Hg" complex, 2, 35 -tri-(9-acetyl-6-0-(mesitylenesulphonyl)-guanosine, guanosine 5 -phosphate, Cu" complex. ... 

Adenine Purine 6-amino Adenosine Adenylic acid... 

Adenine Purine 6-Amino Adenosine Adenosine S -phosphate, adenylic acid, AMP... 

Factors controlling calcium homeostasis are calcitonin, parathyroid hormone(PTH), and a vitamin D metabolite. Calcitonin, a polypeptide of 32 amino acid residues, mol wt - SGOO, is synthesized by the thyroid gland. Release is stimulated by small increases in blood Ca " concentration. The sites of action of calcitonin are the bones and kidneys. Calcitonin increases bone calcification, thereby inhibiting resorption. In the kidney, it inhibits Ca " reabsorption and increases Ca " excretion in urine. Calcitonin operates via a cyclic adenosine monophosphate (cAMP) mechanism. 

CycHc adenosine monophosphate (cAMP), produced from ATP, is involved in a large number of ceUular reactions including glycogenolysis, Hpolysis, active transport of amino acids, and synthesis of protein (40). Inorganic phosphate ions are involved in controlling the pH of blood (41). The principal anion of interceUular fluid is HP (Pig. 3) (41). 

AMP, ADP, and ATP = adenosine mono-, di-, and triphosphate IMP = inosine 5 -monophosphate AICAR = 5 -phosphoribosyl-5-amino-4-imida2olecarboxamide DAP = diaminopimelic acid PRPP = phosphoribosyl pyrophosphate a — KGA = a-ketoglutaric acid Orn = ornithine Cit = citnilline represents the one carbon unit lost to tetrahydrofolate as serine is converted to glycine. 

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... 

Amino-2 -deoxypurines. 2 -AmiQo-2 -deoxyadenosine (15) is a naturally occurring A[-nucleoside isolated from A.ctinomadura that shows antknycoplasmal activity (1,4). Adenosine is the direct precursor for its biosynthesis (30). 2 -Arnino-2 -deoxyguanosine (16), isolated from a strain of Enterobacter cloacae (1,4), shows the growth of HeLa S3 cells and Sarcoma 180 in vivo and has been tested for antibacterial activity. 

Amino-3 -deoxyadenosine. 3 -Amino-3 -deoxyadenosine (17) is elaborated by Cordyceps militarise Aspergillus nidulanSe and Helminthosporium (3,4). The biosynthesis proceeds direcdy from adenosine. Compound (17) inhibits RNA polymerase, but not DNA polymerase, and replaces the adenosyl residue at the 3 -terminus of tRNA. Phenylalanyl-(3 -amino-3 -deoxyadenosyl)-tRNA has acceptor but not donor activity (31,32). Compound (17) also inhibits retroviral RNA-dependent DNA polymerase (33). 

Adenosine, 6-amino-9-P-ribofuranosyl-9-ff-purine (see Table 1), is an endogenous nucleoside found in all ceUs of the body. Its ubiquitousness suggests that adenosine functions as an autocoid and that its actions are mediated by specific receptors on the plasma membranes of all ceUs. 

The most common example of this process in living organisms is the reaction of the amino acid methionine with adenosine triphosphate (ATP Section 5.8) to give S-adenosylmethionine. The reaction is somewhat unusual in that the biological leaving group in this SN2 process is the triphosphate ion rather than the more frequently seen rliphosphate ion (Section 11.6). 

Thiamine can be considered to be the product of the quatemization of 4-methyl-5-(2-hydroxymethyl)thiazole (5) by an active derivative of 4-amino-5-(hydroxymethyl)-2-methyl pyrimidine (4) (Scheme 2). In living cells, pyramine can be activated by conversion into the diphosphate 7, via monophosphate 6, and the substrate of the enzyme responsible for the quatemization is not the thiamine thiazole, but its phosphate 8. The product of the condensation, thiamine phosphate (9), is finally converted into diphosphate 2—the biochemically active derivative—by hydrolysis to free thiamine, followed by diphosphorylation, or more directly, in some cases. Enzymes are known for all of the steps depicted in Scheme 2, and adenosine triphosphate (ATP) is, as usual, the phosphate donor. 

The organism utilized is a mutant of E. coli blocked in the synthesis of aromatic amino acids before the shikimate step. Cells are first grown in the presence of adenosine, a technique that temporarily derepresses the system of en-... 

From this observation of the inhibition by adenosine, and other observations, Newell and Tucker suspected the existence of a common synthetic pathway for adenosine and thiamine, and proved (with the help of a collection of mutants) that the bifurcation occurred after the 5-amino- l-(P-D-ribofura-nosyl)imidazole 5 -phosphate (46) step (Scheme 23). Finally, they found that 5-amino-l-(0-D-ribofuranosyl)imidazole (47), labeled with l4C in the imidazole ring, was incorporated into pyramine without significant loss of molar radioactivity by a mutant that is able to use this nucleoside (presumably after phosphorylation).53,54... 

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