30286
Here , a two - photon resonance - enhanced ionization scheme is presented that utilizes the 1 pi pi * transition , localized on the DNA base , to elucidate the base - specific ionization in a deprotonated nucleotide .
 Chemical: nucleotide
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: nucleotide