nucleoside noun. ['nju:klɪǝsʌɪd] E20.
[from NUCLEO- + GLYCO)SIDE.]
Biochemistry. A compound in which a sugar (usu. ribose or deoxyribose) is linked to a purine or pyrimidine base to form a glycoside; spec. such a compound derived from a nucleic acid by hydrolysis.

■ nucleo'sidase noun an enzyme which catalyses the hydrolysis of a nucleoside into its constituent base and sugar, or catalyses the reaction between a nucleoside and phosphate to yield a base and a sugar phosphate E20.

[TahlilGaran] English Dictionary ▲