. Author manuscript; available in PMC: 2006 Mar 8.

Published in final edited form as: J Am Chem Soc. 1996 Jul 31;118(30):7178–7189. doi: 10.1021/ja9609157

Table 2.

Measured Zero-Pressure Arrhenius Activation Parameters for the Dissociation of Doubly Protonated Bradykinin and Its Variants^a

peptide	activation energy (eV)	frequency factor (s⁻¹)	major fragments	minor fragments
[Ala⁶]-bradykinin	0.74	10⁷	b₂	b₃ – H₂O, M²⁺ – H₂O, y₇
bradykinin	0.84	10⁸	b₂	b₃ – H₂O, M²⁺ – H₂O, y₇
des-Pro²-bradykinin	0.77	10⁷	b₂	M²⁺ – H₂O, y₆
Lys-bradykinin*	1.2	10¹⁰	RP⁺	M²⁺ – H₂O, RPP⁺ – H₂O, b₂, y₇
methyl ester of bradykinin	0.82	10⁶	M²⁺ – H₂O	b₂, b₃ – H₂O

Activation energies have standard deviations between 0.04 and 0.1 eV. Those processes for which calculations indicate the measured Arrhenius parameters are lower than the “high-pressure” limit values within the error of the experiment are indicated by an asterisk.