26757
It was revealed that Arg - Arg pairings become thermodynamically stable ( about - 1 kcal / mol ) as the dielectric constant increases to 46 . 8 ( DMSO ) , in good agreement with the results of the PDB survey .
 Arg - Arg
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 Arg - Arg