sentences:  Arg29 is thought to play a role in substrate binding, while Glu76 is thought to play a role in the orienting the active site for catalysis.The overall hydrophobic environment of the active site plays a critical role in favoring the neutral amine form of Lys115, a key residue involved in the formation of a Schiff base intermediate.Another important lysine residue, Lys116, is thought to play an important role in the positioning of Lys115 in the active site.