User:Amy Kerzmann/Sandbox 5: Difference between revisions
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Ile16 appears to be too far from the active site to influence substrate binding directly, doesn't it? However, the protonated form of Ile16 is capable of forming a salt-bridge with Asp194, which opens the substrate-binding pocket <ref>Bender ML, Kézdy FJ. The Current Status of the α-Chymotrypsin Mechanism. J. Amer. Chem. Soc. 1964; 86(18):3704–3714. [http://pubs.acs.org/doi/abs/10.1021/ja01072a020 Bender & Kézdy]</ref>. Conversely, when Ile16 is deprotonated at high pH, it can no longer interact with Asp194, thereby allowing Asp194 to shift position and obstruct the substrate from entering the active site. The 'closed' conformation is further stabilized by a hydrogen bond between Asp194 and His40. In this manner, Asp194 acts as a gate for the substrate-binding pocket, with the ionization state of Ile16 acting as the latch. | Ile16 appears to be too far from the active site to influence substrate binding directly, doesn't it? However, the protonated form of Ile16 is capable of forming a salt-bridge with Asp194, which opens the substrate-binding pocket <ref>Bender ML, Kézdy FJ. The Current Status of the α-Chymotrypsin Mechanism. J. Amer. Chem. Soc. 1964; 86(18):3704–3714. [http://pubs.acs.org/doi/abs/10.1021/ja01072a020 Bender & Kézdy]</ref>. Conversely, when Ile16 is deprotonated at high pH, it can no longer interact with Asp194, thereby allowing Asp194 to shift position and obstruct the substrate from entering the active site. The 'closed' conformation is further stabilized by a hydrogen bond between Asp194 and His40. In this manner, Asp194 acts as a gate for the substrate-binding pocket, with the ionization state of Ile16 acting as the latch. | ||
==See Also== | |||
* [[Serine Proteases]], a later version of the present article. | |||
==References== | ==References== | ||
<references /> | <references /> | ||