| 释义 |
nucleoside Biochem.|ˈnjuːklɪəsaɪd|
[ad. G. nucleosid (Levene & Jacobs 1909, in Ber. d. Deut. Chem. Ges. XLII. 2475), f. after glucosid glucoside: see nucleo-.]
Any compound in which a sugar (usu. ribose or deoxyribose) is linked glycosidically to a purine or pyrimidine base; spec. such a compound derived from a nucleic acid by hydrolysis. (See quot. 1973.)
1911[see nucleotide]. 1911[see adenosine]. 1931Levene & Bass Nucleic Acids vi. 126 The name ‘nucleoside’ was assigned to the substances of this group for the reason that..they contain sugar in a glucosidic union, and..the substances linked to the sugars are nuclein bases. 1946Nature 24 Aug. 275/2 Miss Mejbaum has found..that the pentose contained in pyrimidine nucleotides (uridylic acid and cydidylic [read cytidylic] acid) and nucleosides (uridine) are not determined by her method. 1969New Scientist 10 July 65/2 A nucleoside like adenosine or inosine. 1973[see nucleotide].
Hence ˈnucleosidase [-ase], any enzyme which catalyses the hydrolysis of a nucleoside into its constituent base and sugar, or the reaction between a nucleoside and phosphate to yield a base and a sugar phosphate.
1911Levene & Medigreceanu in Jrnl. Biol. Chem. IX. 396 Under the influence of mineral acids nucleosides are readily hydrolyzed into their components. The same cleavage can be brought about by the action of enzymes present in the plasma of most of the organs tested in that direction... Since this reaction is brought about by an enzyme different from the other nucleolytic enzymes, it may be proper to refer to it under the name of Nucleosidase. 1935Biochem. Jrnl. XXIX. 1100 If adenine nucleosidase is present it must therefore be only in relatively small amounts. 1955Chargaff & Davidson Nucleic Acids I. xv. 600 The enzymic cleavage of N-glycoside bonds of nucleic acid derivatives was first observed in nucleosides, and the term ‘nucleosidases’..is still used. In the current literature this name tends to be replaced by the designations ‘nucleoside phosphorylases’ and ‘nucleoside hydrolases’. |