Porcine elastase

A was supported by a 3D X-ray structure of the inhibitor at the closely related porcine elastase (Navia, 1987) (Figure 13.12). After initially reversible inhibition (Figure 13.12, top two rows), time-dependent irreversible inhibition through covalent bonding of the dihydrothiazine ring of the inhibitor to the His-57 residue of the active site of the enzyme increasingly takes over (Figure 13.12, bottom row). Peptidyl chloromethyl ketones, known unspecific inhibitors, act in similar fashion. 

The results obtained for porcine elastase have revealed that the -amino groups of both lysines 224 and 87 have normal pX s (about 10.3) and nucleophilicities anticipated for primary amines of this pXg. That is, the second order rate constants for the reaction of the unprotonated -amino groups of these lysine residues with acetic anhydride fit approximately on the Bronsted plot for the reaction of acetic anhydride with a variety of amines. The results for valine-16, which is known to be in a salt linkage in the interior of the enzyme, indicate that this a-amino group has an apparent pX of 9.7 but a nucleo-philicity of only 4% of that anticipated from the Bronsted plot for an amine of this p/. The unusually low reactivity of this valine isconsistent with the significant steric hindrance that would be expected from a resi-... 

This figure shows that two proteins that have very similar structures can have widely differing chemical makeup, a) shows a full-atom model of porcine elastase (lest.pdb, 240 amino acids). The atoms are colored according to the chemical composition of the respective residue (red = positively charged, blue = negatively charged, yellow = polar, white = nonpolar), b) shows the same... 

FIGURE 1.7 Product ion mass spectra of [M+ 19H] porcine elastase derived from (a) CID of [M+ and (b) post-ion/ion proton transfer reactions. (Reproduced from... 

Hogan, J.M. McLuckey, S.A. Charge state dependent collision-induced dissociation of native and reduced porcine elastase. J. Mass Spectrom. 2003, 38, 245-256. 

Nonpowdery polymer easy to filter can be used in a column, used for synthesis of linear tetrapeptides, and peptide substrate for porcine elastase Tetrapeptide synthesis... 

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