Figure 5

Proposed protein-internal hydrogen bond network in PSGR in the active state. The figure represents a snapshot out of the last 10 ns of free MD simulation (1^st β-ionone simulation in the active state listed in Table 2). The protein backbone in yellow, β-ionone in orange sticks, hydrogen bond network forming protein residues in grey sticks. Helices numbered in roman numbers. Upon protein activation, the Ser111^3.40/Asn194^5.51 hydrogen bond.and the Lys185^5.42/Asp190^5.47 salt bridge are broken. A new hydrogen bond is formed between Ser107^3.36 and Tyr251^6.48.