Model Simulations of the Thermal Dissociation of the TIK(H+)2 Tripeptide: Mechanisms and Kinetic Parameters

摘要: Direct dynamics simulations, utilizing the RM1 semiempirical electronic structure theory, were performed to study thermal dissociation of doubly protonated tripeptide threonine–isoleucine–lysine ion, TIK(H+)2, for temperatures 1250–2500 K, corresponding classical energies 1778–3556 kJ/mol. The number different fragmentation pathways increases with increase in temperature. At 1250 K there are only three pathways, one contributing 85% fragmentation. In contrast, at 2500 61 and not dominates. same ion is often formed via 14 m/z values product ions. backbone side-chain fragmentations occur by concerted reactions, simultaneous proton transfer bond rupture, also homolytic ruptures without transfer. For each temperature TIK(H+)2 probability versus time exponential, accord Rice–Ramsperger–Kassel–Marcus transit...