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We present here the crystal structure of the two - domain receptor - binding region of PfEBA - 140 in complex with a glycan containing sialic acid .
 Chemical: sialic acid
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: sialic acid