Inosinic add

Poly(U) = poly(uridylic add), poly(l + C) = equimolar complex of poly(inosinic add) and poly(cytidylic add), poly (A + U) = equimolar complex of poly(adenylic add) and polyfnridylic add), RNA = polyribonucleic add, DNA = polydeoxyribonucleic add, dDNA = denatured DNA... 

Adenosine 5 -monophosphate (AMP) is synthesized de novo from inosinic add (see Purine biosynthesis) and also arises in reactions in which pyrophosphate and AMP are formed from adenosine triphosphate (e.g. in the synthesis of aminoacyl-tRNA). 

Inosinic add is the parent substance of the two purine nucleotides adenosine 5 -phosphate adenylic add) and guanosine 5 -phosphate (guanylic add), both components of nucleic acids. It is also the parent compound of uric acid, which is the final excretion form of nitrogen in birds and in reptiles. 

Figure 4. Separation of ribonucleoside monophosphofic acids. Conditions 250-cm anion exchange column gradient, 0.01M KHgPO containing HsPOi, (pH 2.6) to 0.15M KHiFO in 30 min column tempera-ture, 70 C detector, UV at 254 nm. 1, cyti-dine-S -monophosphoric acid 2, uridine-5 -monophosphoric acid 3, adenosine-5 -mon-ophosphofic acid 4, inosine-5 -monophosphoric acid 5, 3, 5 -cyclic adenosine mono-phosphoric add 6, guanosine-5 -monophosphoric acid (36).

NMDA, Af-methyl-D-aspartate AMPA, a-amino-3-hydroxy-5-methyl-isoxazole-4-proprionic add 1S,3R-ACPD, L-amino-cydopentane-lS,3R-dicarboxylic add IP3, inosine triphosphate... 

Inosinic and Adenylic Adds, Similarly, Levene and Harris found that the adenylic acid from ribosenucleic acid can be deaminated to an inosinic acid which undergoes hydrolysis at its own pH to give hypo-xanthine and 3-phosphoribose. On the other hand, Thannhauser had shown that ammoniacal hydrolysis of the adenylic acid gives adenosine and phosphoric acid. 

As for triplexes the effect of structural modifications has also been studied for DNA-tetraplexes. The simulations on structures containing inosine, 6-thioguanine and 6-thiopurine indicate that a nucleic add stem formed fixnn G-tetrads can easily incorporate inosine without any marked effects on structure and stability. On the other hand, 6-thioguanine and 6-thiopurine have more or less adverse effects. They cause a destabilization of the tetraplex structure... 

Hypoxanthine, on the other hand, which accounts for only a fifth or so of the urinary uric acid is an active intermediate. It is degraded to xanthine and then to uric add by xanthine oxidase. This enzyme is found mainly in liver, kidney, and bowel, while guanase is widely distributed and would quickly deaminate any guanine formed. The product xanthine is a poor substrate for hypoxanthine phosphoribosyltrans-ferase (HPRT). Most of the hypoxanthine formed is reutiliiced by conversion to inosinic acid. Similar conclusions were reached by Ayvazian and Skupp in 1965 when they administered C-labeled purines to patients (A2). Furthermore, these studies and those earlier studies show that the xanthine is converted to hypoxanthine, presumably at the nucleotide level, and on the basis of what we know about microorganisms, we would assume it to be via guanine nucleotides (M2). Since label was found in urinary 7-methylguanine as early as 4 hours after administration of C-labeled purines, and since methylation of RNA occurs at the macromolecular level (B13), interconversion must be rapid and incorporation of some of these products into nucleic acids must also occur quickly. 

Inosine, /nov kypoxamtkmosiae, hypoxanthlae riboside, 9P-D-ribofimmo lkypoxaiilkme a P-glycosi-dic nucleoside of n-ribose and hypoxanthine, M, 268.23, m.p. 218°C (d.), [a]g -73.6° (c = 2.5, 0.01 M NaOH). It occurs free, is particularly abundant in meat and yeast, and is formed by dephosphorylation of inosine phosphates. It fulfills a sprafic function as a component of the anticodon of certain tRNA spe-des (see Rare nncleic add bases). 

The conversion of inosinic acid to guanylic add has been demonstrated in bone marrow preparations... 

In order to observe regularly the enzymatic exchange reaction, it was necessary to add inosinic acid to the extract and limit de novo synthesis by omitting bicarbonate from the system. When the incubation was carried out in the absence of both bicarbonate and added inosinic acid, labeled glycine and formate were converted into inosinic acid in the ratio expected from de novo synthetic reactions. Inosine and hypoxanthine could not replace inosinic acid, thus demonstrating that the latter was the specific substrate in the enzymatic exchange reaction. 

Glutamic, inosinic and guanylic acids and their sodium and potassium salts can be used as flavour enhancers, individually or in combination, up to the maximum allowable amount. The permissible amount of glutamic acid in foodstuffs in general (excluding soft drinks) is 10 g/kg. Specified amounts of this amino add and nucleotides are prescribed for condiment preparations. 

The yields of L-tryptophan produced by this method are impressive from 6 g of indole and 8 g of pyruvate in 100 ml of culture broth, 10 g of amino acid have been obtained. It was found important to add to the reaction mixture inosine, which form an insoluble complex with the synthesized L-tryptophan. When indole was replaced by 5-hydroxy-, 5-methyl- or 5-amino-indole, the corresponding 5-substituted L-trypto-phan was synthesized 449). 

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