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The pseudouridine synthase TruB handles 5-fluorouridine in RNA as a substrate, converting it into two isomeric hydrated products. Unexpectedly, the two products differ not in the hydrated pyrimidine ring but in the pentose ring, which is epimerized to arabinose in the minor product. This inversion of stereochemistry at C2' suggests that pseudouridine generation may proceed by a mechanism involving a glycal intermediate or that the previously proposed mechanism involving an acylal intermediate operates but with an added reaction manifold for 5-fluorouridine versus uridine. The arabino product strongly disfavors a mechanism involving a Michael addition to the pyrimidine ring. 相似文献
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Edward J. Miracco Bogdan Bogdanov Eugene G. Mueller 《Rapid communications in mass spectrometry : RCM》2011,25(18):2627-2632
As part of the investigation of the pseudouridine synthases, 5‐fluorouridine in RNA was employed as a mechanistic probe. The hydrated, rearranged product of 5‐fluorouridine was isolated as part of a dinucleotide and found to undergo unusual fragmentation during mass spectrometry, with the facile loss of HNCO from the product pyrimidine ring favored over phosphodiester bond rupture. Although the loss of HNCO from uridine and pseudouridine is well established, the pericyclic process leading to their fragmentation cannot operate with the saturated pyrimidine ring in the product of 5‐fluorouridine. Based on the MSn results and calculations reported here, a new mechanism relying on the peculiar disposition of the functional groups of the product pyrimidine ring is proposed to account for the unusually facile fragmentation. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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BłAŻEJ JAN WRÓBEL 《Proceedings Mathematical Sciences》2011,121(1):45-75
We examine weighted L
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boundedness of g-functions based on semigroups related to multi-dimensional Laguerre function expansions of Hermite type. A technique of vector-valued
Calderón–Zygmund operators is used. 相似文献
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