9645
Mis - incorporation causes the transcription elongation complex to backtrack , releasing a single strand 3 ' - RNA segment bearing a noncognate residue , which is hydrolyzed by the active center that carries two Mg ( 2 + ) ions .
 Chemical: Mg ( 2 + )
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: Mg ( 2 + )