sentences:  This distance makes it unlikely that the positive charge of Lys116 is able to affect the pKa of Lys115.Instead through hydrogen bonds with Ser16 and Met210, Lys116 likely holds Lys115 into position in a hydrophobic pocket of the active site.This positioning disrupts the stability of the protonated ammonium cation of Lys115, suggesting that the perturbation of Lys115's pKa occurs through a 'desolvation effect'.