5129
Like almost all Type IIB systems , BcgI needs two unmethylated sites for nuclease activity ; it cuts both sites upstream and downstream of the recognition sequence , hydrolyzing eight phosphodiester bonds in a single synaptic complex .
 Chemical: phosphodiester
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: phosphodiester