************ The 7th Lab Seminar ***************************************

Title :
A Low-Barrier Hydrogen Bond in the Catalytic Triad of Serine Proteases 
(Perry A. Frey, Sean A. Whitt, John B. Tobin, Science, 1994, 264, 1927.)

Speaker : KITAMURA Yukichi

Date : Thu. Oct. 18th, 1:30 pm

Abstract
Spectroscopic properties of chymotrypsin and model compounds indicate that 
a low-barrier hydrogen bond participates in the mechanism of serine protease 
action. A low-barrier hydrogen bond between N_sigma_1 of His57 and the beta-
carboxyl group of Asp102 in chymotrypsin can facilitate the formation of the 
tetrahedral adduct, and the nuclear magnetic resonance properties of this 
proton indicate that it is a low-barrier hydrogen bond. These conclusions 
are supported by the chemical shift of this proton, the deuterium isotope 
effect on the chemical shift, and the properties of hydrogen-bonded model 
compounds in organic solvents, including the hydrogen bond in cis-urocanic 
acid, in which the imidazole ring is internally hydrogen-bonded to the carboxyl 
group.

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