10110
Two kinds of cation - binding sites , which we named intra - subunit and inter - subunit , have been observed in crystal structures of ALDHs , and based on reported crystallographic data , we here propose the existence of a third kind located in the central cavity of some tetrameric ALDHs .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
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