6-aminopurine, adenine

Nucleophilic substitution (S Ar) can be carried out on purine itself as well as on halo-, alkoxy- and alkylsulfanylpurines. The Chichibabin reaction (see p 278) of purine with KNH2 in liquid ammonia leads to 6-aminopurine (adenine) 3 ... 

Deamination of aminopurines Adenine undergoes deamination to produce hypoxanthine, and guanine is deaminated to xanthine. 

The existence of two separate enzymes in animal tissues responsible for the liberation of ammonia from each of the two aminopurines, adenine and guanine, the latter specific for the free purine and the former for the nucleosides, was initially presented by Jones and his colleagues 11, 12). In 1928, Schmidt 13-15) demonstrated that AMP aminohy-drolase was responsible for the appearance of inosinic acid in muscle and for at least a portion of ammonia liberated during contraction. He showed not only a marked specificity for deamination of 5 -AMP but also provided the first clue that muscle adenylic acid (5 -AMP) and yeast adenylic acid (3 -AMP) were different compounds. Initial evidence for guanine and adenosine aminohydrolase including aspects of the specificity were also described by Schmidt 16). Additional details regarding development of interest in purine aminohydrolases are available in several excellent reviews 17-20). 

Aminopurine is adenine and will appear numerous times in this chapter... 

Another compound of interest is adenine [73-24-5] or 6-aminopurine (53) derived from pheny1a 2oma1ononitri1e (92). The introduction of the dicyanostyryl moiety has led to the industriali2ation of several methine dyes such as the Cl Disperse Yellow [6684-20-4] (54) (93). The Cl Disperse Blue 354 [74239-96-6] (55) also represents a new class of anTinoarylneutrocyariine dyes with a brilliant blue shade (94). The dimer of malononitrile is also used for the synthesis of new dyes (95). 

In a combined experimental/computational study, the vibrational spectra of the N9H and N7H tautomers of the parent purine have been investigated [99SA(A) 2329]. Solvent effects were estimated by SCRF calculations. Vertical transitions, transition dipole moments, and permanent dipole moments of several low-lying valence states of 2-aminopurine 146 were computed using the CIS and CASSCF methods [98JPC(A)526, 00JPC(A)1930]. While the first excited state of adenine is characterized by an n n transition, it is the transition for 146. The... 

The photophysical properties of adenine have intrigued chemists from early on. Broo studied adenine and 2-aminopurine (2AP) in order to understand their differences in photophysical properties. Adenine like all natural nucleobases has very short excited state lifetimes and low quantum yields of fluorescence, while 2AP, which differs from adenine in the position of the amino group, has long lifetimes and strong fluorescence, making it a very useful fluorescent probe. In Broo s work it was observed that the first excited state is a nn at vertical excitation but crosses with an nn state which becomes the Si state adiabatically at the minimum. The large out-of-plane distortion on the nn state opens up a deactivation channel in adenine compared to 2AP. In 2AP, on the other hand, the Si state always has a 7T7r character. 

Three fluorescent purine analogs will be described here 2-aminopurine (2AP) [183] and 8-vinyladenine (8VAD), both of which mimic adenine, and N1,N6-ethenoadenine (e-AD). Their structures are shown in Figure 11-15. 2AP is probably the most widely used fluorescent DNA base analog, being utilized as a probe for DNA conformational dynamics [184, 185], due to the environmental specificity of... 

Serrano-Andres L, Merchan M, Borin AC (2006) Adenine and 2-aminopurine paradigms of modem theoretical photochemistry. Proc Natl Acad Sci USA 103 8691-8696... 

Broo A (1998) A theoretical investigation of the physical reason for the very diffferent luminescence properties of the two isomers adenine and 2-aminopurine. J Phys Chem A 102 526... 

Mishra SK, Shukla MK, Mishra PC (2000) Electronic spectra of adenine and 2-aminopurine an ab initio study of energy level diagrams of different tautomers in gas phase and aqueous solution. Spectrochim Acta A 56 1355... 

Mennucci B, Toniolo A, Tomasi J (2001) Theoretical study of the photophysics of adenine in solution tautomerism, deactivation mechanisms, and comparison with the 2-aminopurine fluorescent isomer. J Phys Chem A 105 4749... 

The results indicate that C-6 in purine and 2-aminopurine (17) is more reactive than C-8 or C-2, while the primary attack at C-8 in adenine and 6-ethoxypurine (18) indicates that C-8 is more reactive than C-2. The order of reactivity toward a-hydroxyalkyl radicals in the purine system is therefore C-6 > C-8 > C-2. 

The result is surprising, as with the structurally quite similar adenine (6-aminopurine), N-substitution occurs only at the amino group 46) ... 

This enzyme [EC 2.1.1.72] catalyzes the reaction of S-adenosyl-L-methionine with an adenine residue in DNA to produce S-adenosyl-L-homocysteine and a 6-methyl-aminopurine residue in DNA. 

Ref Bureau of Ordnance, Navy Dept, Italian and French Explosive Ordnance. OP 1668, Washington, DQ1946), 63 Adenine. Same as 6- Aminopurine Adeslvo (Ital). Adhesive Adhesion is the sticking together of substances in contact with each other. The subject is discussed in the following ref-... 

One way in which chemical compounds can induce base substitution mutation is through their incorporation into the structure of DNA itself. Thus, 5-bromodeoxyuridine (or bromouracil) can replace thymidine in DNA, where it serves as an efficient mutagenic agent.767 2-Aminopurine, an analog of adenine, pairs with thymine, just as does adenine when incorporated into DNA. 

Cytosine (2-hydroxy-6-amino-pyrimidine), uracil (2,6-dihydroxypyrimidine), and thymine (5-methyluracil) are pyrimidine derivatives adenine (6-aminopurine), guanine (2-amino-6-hy-droxypurine), and xanthine (2,6-dihydroxypurine) are purine derivatives (Fig. 5). 

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