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NMR spectroscopy was also used to examine the hSOD1 mutants C57A , C146A , and C57A / C146A , which are unable to form the structurally conserved disulfide bond in SOD1 , in order to investigate the role of these cysteines during hSOD1 copper acquisition .
 Chemical: disulfide; Chemical: cysteines
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: disulfide; Chemical: cysteines