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245	1	0	_aCharacterization of c-tocopherol methyltransferases from Capsicum annuum L and Arabidopsis thaliana
490	0		_vEur. J. Biochem., 270(1), p.84-92, 2003
520	3		_aTocopherols are essential micronutrients in human and animal nutrition due to their function as lipophilic antioxidants. They are exclusively synthesized by photosynthetic organisms including higher plants. Despite the attributed beneficial health effects and many industrial applications, research on the tocopherol biosynthetic pathway and its regulation in plants is still limited. In the work presented here we performed a detailed biochemical characterization of a c-tocopherol methyltransferase (c-TMT)from Arabidopsis thaliana and of a c-TMT purified from Capsicum annuum fruits,a tissue with high accumulation of tocopherols. The biochemical characteristics of both enzyme preparations were remarkably similar including substrate specificities. Both enzymes converted d- and c- into b- and a-tocopherol, respectively,b ut b-tocopherol was not accepted as a substrate, pointing to a specificmethylation at the C(5)-position of the tocopherol aromatic head group. A kinetic analysis performed with the Arabidopsis enzyme was consistent with an iso-ordered bi-bi type reaction mechanism. Our results emphasize the role of c-TMT in regulating the spectrum of accumulated tocopherols in plants
650	1	4	_aARABIDOPSIS
650	1	4	_aCAPSICUM
650	1	4	_aC-TOCOPHEROL
650	1	4	_aMETHYLTRANSFERASE
650	1	4	_aVITAMIN E
700	1	2	_aKoch, M.
700	1	2	_aLemke, R.
700	1	2	_aHeise, K.P.
700	1	2	_aMock, H.P.
856	4	0	_uhttps://drive.google.com/file/d/1mwV0wTL_Ivygovb761GWVlkJcrTzgrjp/view?usp=drivesdk _zPara ver el documento ingresa a Google con tu cuenta: @cicy.edu.mx
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