21551
Crystallization succeeded only ( i ) when an oxidation - and protease - insensitive protein variant ( C183S - FixK2His6 ) was used , in which C183 was replaced by serine and the C - terminus fused with a hexa - histidine tag , and ( ii ) when this protein was allowed to form a complex with a 30mer double - strand target DNA .
 Chemical: serine; Chemical: C; Chemical: hexa - histidine
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: serine; Chemical: C; Chemical: hexa - histidine