Active site, catalytic epoxidation nature

The catalytic epoxidation step may be considered to be the heart of the SMPO process. Tlie catalyst is prepared in a multistep gas-phase process by treatment of a silica carrier wifh fifanium tetrachloride, heating the obtained material, followed by steaming and silylation. Possible improvements to this process and research on the support material have already been reviewed [1]. Here, we discuss the nature of the active site, the mechanism of epoxidation, and the various catalyst deactivation mechanisms that exist for fhis unique cafalysf. 

Figure 2.3 Serine protease and hydrolase ABPs. (A) Reaction of a general serine hydrolase probe containing a fluorophosphonate (FP) reactive electrophile. This class of probes has been used extensively to label various classes of serine hydrolases including proteases, esterases, lipases and others. (B) The peptide diphenyl phosphonate (DPP) reacts with the serine nucleophile in the active site of serine proteases. This probe is much less reactive than the FP class of probes but is more selective towards serine proteases over other types of serine hydrolases.(C) The natural product epoxomicin contains a keto-epoxide that selectively reacts with the catalytic N-terminal threonine of the proteasome P-subunit. This reaction results in the formation of a stable six-membered ring. This class of electrophile has been used in probes of the proteasome.

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