caffeine synthase

{{short description|Enzyme}}

{{infobox enzyme

| Name = Caffeine synthase

| EC_number = 2.1.1.160

| CAS_number = 155215-94-4

| GO_code =

| image =

| width =

| caption =

}}

Caffeine synthase is a methyltransferase enzyme involved in the caffeine biosynthesis pathway. It is expressed in tea species, coffee species, and cocoa species. The enzyme catalyses the following reactions:{{cite journal |vauthors=Kato M, Mizuno K, Fujimura T, Iwama M, Irie M, Crozier A, Ashihara H | title = Purification and characterization of caffeine synthase from tea leaves | journal = Plant Physiol. | volume = 120 | issue = 2 | pages = 579–86 |date=June 1999 | pmid = 10364410 | pmc = 59297 | doi = 10.1104/pp.120.2.579}}

• S-adenosyl-L-methionine + theobromine $\backslash rightleftharpoons$ S-adenosyl-L-homocysteine + caffeine + H⁺
• S-adenosyl-L-methionine + paraxanthine $\backslash rightleftharpoons$ S-adenosyl-L-homocysteine + caffeine + H⁺
• 7-methylxanthine + S-adenosyl-L-methionine $\backslash rightleftharpoons$ S-adenosyl-L-homocysteine + H⁺ + theobromine

Caffeine synthase is expressed in the Camellia species irrawadiensis, ptilophylla, and sinensis;{{cite journal |vauthors=Kato M, Mizuno K, Crozier A, Fujimura T, Ashihara H | title = Caffeine synthase gene from tea leaves | journal = Nature | volume = 406 | issue = 6799 | pages = 956–7 |date=August 2000 | pmid = 10984041 | doi = 10.1038/35023072 | url = http://eprints.gla.ac.uk/126/1/Kato%2CM_2000pdf.pdf}} the Coffea species arabica,{{cite journal |vauthors=Mizuno K, Okuda A, Kato M, Yoneyama N, Tanaka H, Ashihara H, Fujimura T | title = Isolation of a new dual-functional caffeine synthase gene encoding an enzyme for the conversion of 7-methylxanthine to caffeine from coffee (Coffea arabica L.) | journal = FEBS Lett. | volume = 534 | issue = 1–3 | pages = 75–81 |date=January 2003 | pmid = 12527364 | doi = 10.1016/S0014-5793(02)03781-X| doi-access = free }}{{cite journal |vauthors=Uefuji H, Ogita S, Yamaguchi Y, Koizumi N, Sano H | title = Molecular cloning and functional characterization of three distinct N-methyltransferases involved in the caffeine biosynthetic pathway in coffee plants | journal = Plant Physiol. | volume = 132 | issue = 1 | pages = 372–80 |date=May 2003 | pmid = 12746542 | pmc = 166982 | doi = 10.1104/pp.102.019679 }} and canephora;{{cite journal |vauthors=McCarthy AA, Biget L, Lin C, Petiard V, Tanksley SD, McCarthy JG | title = Cloning, expression, crystallization and preliminary X-ray analysis of the XMT and DXMT N-methyltransferases from Coffea canephora (robusta) | journal = Acta Crystallographica Section F | volume = 63 | issue = Pt 4 | pages = 304–7 |date=April 2007 | pmid = 17401201 | pmc = 2330209 | doi = 10.1107/S1744309107009268 }} and in Theobroma cacao.{{cite journal |vauthors=Yoneyama N, Morimoto H, Ye CX, Ashihara H, Mizuno K, Kato M | title = Substrate specificity of N-methyltransferase involved in purine alkaloids synthesis is dependent upon one amino acid residue of the enzyme | journal = Mol. Genet. Genomics | volume = 275 | issue = 2 | pages = 125–35 |date=February 2006 | pmid = 16333668 | doi = 10.1007/s00438-005-0070-z }}