Amino-Purines

Purines, N-alkyl-N-phenyl-synthesis, 5, 576 Purines, alkylthio-hydrolysis, 5, 560 Mannich reaction, 5, 536 Michael addition reactions, 5, 536 Purines, S-alkylthio-hydrolysis, 5, 560 Purines, amino-alkylation, 5, 530, 551 IR spectra, 5, 518 reactions, 5, 551-553 with diazonium ions, 5, 538 reduction, 5, 541 UV spectra, 5, 517 Purines, N-amino-synthesis, 5, 595 Purines, aminohydroxy-hydrogenation, 5, 555 reactions, 5, 555 Purines, aminooxo-reactions, 5, 557 thiation, 5, 557 Purines, bromo-synthesis, 5, 557 Purines, chloro-synthesis, 5, 573 Purines, cyano-reactions, 5, 550 Purines, dialkoxy-rearrangement, 5, 558 Purines, diazoreactions, 5, 96 Purines, dioxo-alkylation, 5, 532 Purines, N-glycosyl-, 5, 536 Purines, halo-N-alkylation, 5, 529 hydrogenolysis, 5, 562 reactions, 5, 561-562, 564 with alkoxides, 5, 563 synthesis, 5, 556 Purines, hydrazino-reactions, 5, 553 Purines, hydroxyamino-reactions, 5, 556 Purines, 8-lithiotrimethylsilyl-nucleosides alkylation, 5, 537 Purines, N-methyl-magnetic circular dichroism, 5, 523 Purines, methylthio-bromination, 5, 559 Purines, nitro-reactions, 5, 550, 551 Purines, oxo-alkylation, 5, 532 amination, 5, 557 dipole moments, 5, 522 H NMR, 5, 512 pJfa, 5, 524 reactions, 5, 556-557 with diazonium ions, 5, 538 reduction, 5, 541 thiation, 5, 557 Purines, oxohydro-IR spectra, 5, 518 Purines, selenoxo-synthesis, 5, 597 Purines, thio-acylation, 5, 559 alkylation, 5, 559 Purines, thioxo-acetylation, 5, 559... 

The following papers may bo consulted for the ionization potentials and electron affinities of cytosine and of its complexes with different partners cytosine,171-173-177-178,180.184.186.200,201,203.207,259,260 guanine-cytosine,171-182 18 -106 2-NH2-purine (amine form)-cytosine, 2-NH2-purine(imine form)-cytosine and 2-NH2-purine(amino form)-cytosine (form 6),190 cytosine-cytosine and cytosine-cytosine-cytosine.171... 

M. J. Robins, S. D. Hawrelak, A. E. Hernandez, and S. F. Wnuk, Nucleic add related compounds. 71. Efficient general synthesis of purine (amino, azido, and triflate)-sngar nucleosides, Nucleosides Nucleotides 11 821 (1992). 

This subject has been reviewed recently by Balls (4S). Three general classes of inhibitors of purine ribonucleotide interconversions may be considered the 6-thio and 6-chloro purines, amino acid analogues, and psicofuranine. 

Peroxisomes are more recently recognized intracellular structures that contain catalase, D-amino acid oxidase, and urate oxidase (Masters and Holmes, 1977). The cytoplasm contains some or all of the enzymes of the glycolytic, pentose phosphate, galactose, uronic acid, glycogen, fructose, mucopolysaccharide, pyrimidine, purine, amino acid, fatty acid biosynthetic, and other metabolic pathways. 

Proteias are metabolized coatiauously by all living organisms, and are ia dyaamic equilibrium ia living cells (6,12). The role of amino acids ia proteia biosyathesis has beea described (2). Most of the amino acids absorbed through the digestioa of proteias are used to replace body proteias. The remaining portioa is metabolized iato various bioactive substances such as hormones and purine and pyrimidine nucleotides, (the precursors of DNA and RNA) or is consumed as an energy source (6,13). 

Subsequent knowledge of the stmcture, function, and biosynthesis of the foHc acid coenzyme gradually allowed a picture to be formed regarding the step in this pathway that is inhibited by sulfonamides. The biosynthetic scheme for foHc acid is shown in Figure 1. Sulfonamides compete in the step where condensation of PABA with pteridine pyrophosphate takes place to form dihydropteroate (32). The amino acids, purines, and pyrimidines that are able to replace or spare PABA are those with a formation that requkes one-carbon transfer catalyzed by foHc acid coenzymes (5). 

The pathways for thiamine biosynthesis have been elucidated only partiy. Thiamine pyrophosphate is made universally from the precursors 4-amino-5-hydroxymethyl-2-methylpytimidinepyrophosphate [841-01-0] (47) and 4-methyl-5-(2-hydroxyethyl)thiazolephosphate [3269-79-2] (48), but there appear to be different pathways ia the eadier steps. In bacteria, the early steps of the pyrimidine biosynthesis are same as those of purine nucleotide biosynthesis, 5-Aminoimidazole ribotide [41535-66-4] (AIR) (49) appears to be the sole and last common iatermediate ultimately the elements are suppHed by glycine, formate, and ribose. AIR is rearranged in a complex manner to the pyrimidine by an as-yet undetermined mechanism. In yeasts, the pathway to the pyrimidine is less well understood and maybe different (74—83) (Fig. 9). 

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. 

Amino groups a to nitrogen are hydrolyzed to the corresponding oxo compounds (as in the purines and pteridines) in bo h acid and alkaline conditions. Schiff bases are reduced to benzylamino derivatives with borohydride. 

As with the purines, the replacement of chloro groups by amino groups has been one of the major building blocks of pyridopyrimidine chemistry, being employed in a great variety of reactions too numerous to catalogue fully, particularly in the piromidic and pipemidic acid fields. 

Purine, 6-amino-2-benzyIoxy-9-methyI-hydrogenolysis, 5, 558 Purine, 2-amino-6-chloro-reactions, 5, 562 Purine, 6-amino-2,8-dichIoro-hydrogenolysis, 5, 563... 

Purine, 2-amino-6,8-dioxo-I,6,7,8-tetrahydro-reactions, 5, 557 Purine, 6-amino-2-fluoro-synthesis, S, 597 Purine, 2-amino-9-methyI-sulfonylation, 5, 551 Purine, 6-amino-2-methyIthio-hydrolysis, 5, 560... 

Purine, 2-amino-1 -methyI-6-thioxo-1,6-dihydro-synthesis, 5, 596 Purine, 8-amino-2-oxo-synthesis, 5, 579 Purine, 8-amino-6-oxo-synthesis, 5, 579... 

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