25849
Moreover , our modeling study suggested that a single hydrogen bond formed between Vc1 . 1 and position 59 of the alpha 10 alpha 9 pocket confers specificity to rat versus human alpha 9 alpha 10 nAChRs .
 hydrogen
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 hydrogen