Enzyme inhibitors polypeptides, based

Activity-based probes (ABPs) are tagged covalent and irreversible enzyme inhibitors. Formation of a stable covalent bond ensures that the inhibitor will remain attached to the polypeptide after protein denaturation, after which the tag (radio-isotope, biotin, fluorophore) allows visualization and/or identification of the thus modified enzyme or enzyme family. The first proteasome ABP described comprised a tritium-labeled lactacystin analog [6,7]. Proteasome bands are visualized on one-dimensional SDS-PAGE (sodium docecylsulfate-polyacrylamide gel electrophoresis) gel in an autoradiogram after treatment with a radiolabeled... 

In the recent studies, the enzyme shows that the overall polypeptide fold of chymotrypsin-like serine protease possesses essential SI specificity determinants characteristic of elastase using the multiple isomorphous replacement (MIR) method and refined to 2.3 A resolution Fig. (5). Structure-based inhibitor modeling demonstrated that EFEa s SI specificity pocket is preferable for elastase-specific small hydrophobic PI residues, while its accommodation of long and/or bulky PI residues is also feasible if enhanced binding of the substrate and induced fit of the SI pocket are achieved [Fig. (6) shows the active sites of serine protease]. EFEa is thereby endowed with relatively broad substrate specificity, including the dual fibrinolysis. This structure is the first report of an earthworm fibrinolytic enzyme component, a serine protease originated from annelid worm [17]. 

Trypsin preferentially catalyzed the condensation of trimethylsilanol under mild conditions (87% HMDS). Subs tial condensation of trimethylsilanol was not observed in the negative control, non-specific protein (i.e. BSA, y-globulins), small molecule (i.e. CaCl2, imidazole, N-methylimidazole), and polypeptide (i.e. poly-L-lysine) reactions in comparison to the raw material (< 1% HMDS). Based on an inqjurity study with small molecule inhibitors (23), the exceptional activity of trypsin and a-chymotrypsin observed in the original enzyme-catalyzed condensation study was soley due to a tryptic impurity. The tertiary... 

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