| 释义 |
nucleotide Biochem.|ˈnjuːklɪətaɪd|
[ad. G. nucleotid (Levene & Mandel 1908, in Ber. d. Deut. Chem. Ges. XLI. 1907): see nucleo- and -ide.]
Any compound in which a phosphate group is linked to the sugar of a nucleoside; spec. any of the compounds of this type obtained by the partial hydrolysis of a nucleic acid, which are the individual monomers of which such acids are composed. (See quot. 1973.)
1908Jrnl. Chem. Soc. XCIV. i. 587 It is suggested that the nucleic acids are composed of simpler complexes, the nucleotides, each formed of phosphoric acid, a carbohydrate, and a base. 1911Jrnl. Biol. Chem. IX. 66 It was demonstrated that the molecule of the complex nucleic acids is composed of nucleotides and these of phosphoric acid, carbohydrate and base linked to one another in the order here given... It is possible to detach from the complex either phosphoric acid alone, giving rise to a nucleoside, or a complex of carbohydrate and base. 1937Nature 30 Oct. 745/2 The co-ferments now described as phosphopyridine nucleotides, the nature of which has been at last worked out. 1952Sci. News XXIV. 33 The complete nucleic acid molecules are generally considered as being built up of nucleotides, linked through the hydroxyl (OH) groups of the sugar and the acid groups of the phosphoric acid. 1957Times 1 Nov. 10/3 The award to Sir Alexander Todd..of the Nobel prize for chemistry..for his work on nucleotides and nucleotide enzymes. 1968Observer (Colour Suppl.) 10 Mar. 15/1 The DNA molecule..is a two-stranded helix. Each strand is built up of smaller molecules called nucleotides. Ibid. 15/2 There are only four kinds of nucleotide, each with a different chemical base. These bases are adenine, thymine, guanine and cytosine. 1971J. Z. Young Introd. Study Man iii. 47 The symbols of the genetic code..are the nucleotides arranged in the helical DNA molecules. 1973Henderson & Paterson Nucleotide Metabolism p. xiv, The terms ‘nucleoside’ and ‘nucleotide’ in the strictest sense refer to N-glycosides, and phosphorylated N-glycosides, respectively, derived from nucleic acids. The term is now used, however, in several broader ways. Thus, adenosine triphosphate (ATP) is not derived from nucleic acids, but is quite legitimately a nucleotide through its relation to adenosine monophosphate (AMP), which is so derived. Other N-ribosides, such as nicotinamide mononucleotide (NMN), are called nucleotides only by extension and analogy, and nicotinamide-adenine dinucleotide (NAD+), nicotinamide-adenine dinucleotide phosphate (NADP+), etc., are called dinucleotides only by a similar process. Flavin mononucleotide (FMN) is a step still further removed, as it contains ribitol instead of ribose, and flavin-adenine dinucleotide similarly extends the meaning of dinucleotide. N-glycosides such as orotidylate (OMP) and adenylosuccinate are called nucleotides through their close relationship to the ‘true’ nucleotides. Ibid. i. 10 In animal cells, a few nucleotides with sugars other than ribose and deoxyribose are known.
Hence ˈnucleotidase [-ase], any enzyme which catalyses the hydrolysis of a nucleotide to a nucleoside and phosphate.
1911Levene & Medigreceanu in Jrnl. Biol. Chem. IX. 395 The enzymes performing this cleavage [of nucleotides to phosphoric acid and carbohydrate-base complex] may be referred to as Nucleotidases. 1932Jrnl. Biol. Chem. XCVI. 462 The optimal activity of the nucleotidase is at a pH > 11. 1970R. W. McGilvery Biochem. xx. 481 The phosphate group of nucleotides is liberated by hydrolysis, catalyzed by nucleotidases. |