6225
Despite the existence of 30 cysteine residues , carboxymethylation prevented the formation of most if not all disulfide bonds that otherwise occurred when the cells were sonicated .
 None
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: GENE 
Text: {0} 
 Entities:  
Answer:
 None