Isocytosine

Structural formula
General
Surname	Isocytosine
other names	2-amino-pyrimidin-4-one
Molecular formula	C 4 H 5 N 3 O
Brief description	white prisms
External identifiers / databases
EC number	203-592-0
ECHA InfoCard	100.003.266
PubChem	66950
Wikidata	Q10859790
properties
Molar mass	111.10 g mol −1
Physical state	firmly
Melting point	276 ° C
safety instructions
GHS labeling of hazardous substances Caution
H and P phrases	H: 302-319
	P: 305 + 351 + 338
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Isocytosine is a heterocyclic organic compound with a pyrimidine backbone. It is an isomer of the nucleobase cytosine , with the amino group and carbonyl group switching places. It is part of the nucleosides isocytidine and pseudoisocytidine .

presentation

Isocytosine can be obtained by condensing guanidine hydrochloride with 3-oxopropanoic acid ("formyl acetic acid", C ₃ H ₄ O ₃ ). In this case, however, the C ₃ component cannot be stored and was therefore replaced by malic acid . This is decarbonylated in concentrated sulfuric acid with elimination of water , so it loses carbon monoxide . The 3-oxopropanoic acid formed in situ condenses with the guanidine in the sulfuric acid solution with double elimination of water.

properties

Isocytosine forms white prisms with a melting point of 276 ° C. It is tautomeric and crystallizes in a 1: 1 ratio of a 1 H and a 3 H variant.

use

Isocytosine is used together with isoguanine to investigate unusual base pairings in DNA .

Individual evidence

^ ^A ^b ^c ^d William T. Caldwell, Harry B. Kime: "A New Synthesis of Isocytosine", J. Am. Chem. Soc. , 1940 , 62 (9), pp. 2365-2365 ( doi : 10.1021 / ja01866a028 ).
↑ ^a ^b Data sheet Isocytosine, ≥99% from Sigma-Aldrich , accessed on October 31, 2013 ( PDF ).
↑ Martin Dračínský, Petr Jansa, Kari Ahonen, Miloš Buděšínský: "Tautomerism and the Protonation / Deprotonation of Isocytosine in Liquid- and Solid-States Studied by NMR Spectroscopy and Theoretical Calculations", European Journal of Organic Chemistry , 2011 , 2011 (8) , Pp. 1544-1551 ( doi : 10.1002 / ejoc.201001534 ).
↑ Andrzej Jaworski, Józef S. Kwiatkowski, Bogdan Lesyng: "Why isoguanine and isocytosine are not the components of the genetic code", International Journal of Quantum Chemistry, Supplement: Proceedings of the International Symposium on Quantum Biology and Quantum Pharmacology , 1985 , 28 (Supplement S12), pp. 209-216 ( doi : 10.1002 / qua.560280720 ).
↑ Christopher Roberts, Rajanikanth Bandaru, Christopher Switzer: "Theoretical and Experimental Study of Isoguanine and Isocytosine: Base Pairing in an Expanded Genetic System", J. Am. Chem. Soc. , 1997 , 119 (20), pp. 4640-4649 ( doi : 10.1021 / ja970123s ).
↑ Xiang-Lei Yang, Hiroshi Sugiyama, Shuji Ikeda, Isao Saito, Andrew H.-J. Wang: "Structural Studies of a Stable Parallel-Stranded DNA Duplex Incorporating Isoguanine: Cytosine and Isocytosine: Guanine Basepairs by Nuclear Magnetic Resonance Spectroscopy," Biophys. J. , 1998 , 75 (3), pp. 1163-1171 ( PMID 9726918 ; PMC 1299791 (free full text); doi : 10.1016 / S0006-3495 (98) 74035-4 ).

[Synthesis_Isocytosine-1] A ^b ^c ^d William T. Caldwell, Harry B. Kime: "A New Synthesis of Isocytosine", J. Am. Chem. Soc. , 1940 , 62 (9), pp. 2365-2365 ( doi : 10.1021 / ja01866a028 ).

[Sigma-2] Data sheet Isocytosine, ≥99% from Sigma-Aldrich , accessed on October 31, 2013 ( PDF ).

[3] Martin Dračínský, Petr Jansa, Kari Ahonen, Miloš Buděšínský: "Tautomerism and the Protonation / Deprotonation of Isocytosine in Liquid- and Solid-States Studied by NMR Spectroscopy and Theoretical Calculations", European Journal of Organic Chemistry , 2011 , 2011 (8) , Pp. 1544-1551 ( doi : 10.1002 / ejoc.201001534 ).

[4] Andrzej Jaworski, Józef S. Kwiatkowski, Bogdan Lesyng: "Why isoguanine and isocytosine are not the components of the genetic code", International Journal of Quantum Chemistry, Supplement: Proceedings of the International Symposium on Quantum Biology and Quantum Pharmacology , 1985 , 28 (Supplement S12), pp. 209-216 ( doi : 10.1002 / qua.560280720 ).

[5] Christopher Roberts, Rajanikanth Bandaru, Christopher Switzer: "Theoretical and Experimental Study of Isoguanine and Isocytosine: Base Pairing in an Expanded Genetic System", J. Am. Chem. Soc. , 1997 , 119 (20), pp. 4640-4649 ( doi : 10.1021 / ja970123s ).

[6] Xiang-Lei Yang, Hiroshi Sugiyama, Shuji Ikeda, Isao Saito, Andrew H.-J. Wang: "Structural Studies of a Stable Parallel-Stranded DNA Duplex Incorporating Isoguanine: Cytosine and Isocytosine: Guanine Basepairs by Nuclear Magnetic Resonance Spectroscopy," Biophys. J. , 1998 , 75 (3), pp. 1163-1171 ( PMID 9726918 ; PMC 1299791 (free full text); doi : 10.1016 / S0006-3495 (98) 74035-4 ).