The use of chymotrypsin to decrease postoperative edema in abrasive surgery.

The transformation of a weak hydrogen bond in the free enzyme into a low-barrier hydrogen bond (LBHB) in the tetrahedral intermediate has been suggested as an important factor facilitating catalysis in serine proteases. In this work, we examine the structure of the H-bond in the Asp102-His57 diad of serine proteases in the free enzyme and in a covalent tetrahedral complex (TC) with a trifluoromethylketone inhibitor. We apply ab initio quantum mechanical calculations to models consisting of a large molecular fragment of the enzyme active site, and the combined effect of the rest of the protein body and the solvation by surrounding bulk water was simulated by a self-consistent reaction field method in our novel QM/SCRF(VS) approach. Potential profiles of adiabatic proton transfer in the Asp102-His57 diad in these model systems were calculated. We conclude that the hydrogen bond in both the free enzyme and in the enzyme-inhibitor TC is a strong ionic asymmetric one-well hydrogen bond, in contrast to a previous suggestion that it is a weak H-bond in the former and a double-well LBHB in the latter.

Chymotrypsin↗

PubMed2004

Inhibition of alpha-chymotrypsin with thiol-bearing substrate analogues in the presence of zinc ion.

We have demonstrated that thiol-bearing analogues of alpha-chymotrysin (alpha-CT) substrates such as (S)-(1-benzyl-2-thiolethyl)-carbamic acid, benzyl ester (3) inhibits alpha-CT, a prototypical serine protease, in the presence of Zn(II) ion. They constitute a novel class of small molecule inhibitors for alpha-CT believed to inhibit the enzyme by forming a ternary complex consisting of alpha-CT, Zn(II) ion, and the inhibitor.

Chymotrypsin↗

PubMed2004

Beta-lactoglobulin/polysaccharide interactions during in vitro gastric and pancreatic hydrolysis assessed in dialysis bags of different molecular weight cut-offs.

The effects of gum arabic, low methylated (LM) pectin or xylan at levels of 0 and 50 wt.% on beta-lactoglobulin (beta-lg) digestibility were studied as well as the interactions between the two macromolecules during in vitro hydrolysis. The proteolysis was performed in a system involving a two-step hydrolysis: either pepsin alone, or pepsin followed by a trypsin/chymotrypsin (T/C) mixture in dialysis bags with molecular weight cut-offs (MWCO) 1000 or 8000 Da. Digestibility was estimated by the N release and by a SDS-PAGE electrophoresis of retentates from the two dialysis bags after hydrolysis. Turbidimetric measurements monitored the structural evolution of mixtures during the two-step hydrolysis. Results showed that beta-lg was almost resistant to peptic digestion and that polysaccharides increased the N release despite a reduction of pepsin activity. This is due to the formation of electrostatic complexes between polysaccharides and beta-lg, which reduced beta-lg aggregation, increasing its solubility. The polysaccharides reduced significantly the beta-lg T/C digestibility as determined using a dialysis bag with a MWCO 1000 Da, without a modification of their enzymatic activities. No significant effect of polysaccharides on the beta-lg digestibility was detected using the dialysis bag with a MWCO 8000 Da. The electrophoresis pattern did not show differences in the profile of retentates in relation with the dialysis bag used. This suggests that non-specific interactions could occur during the second step of hydrolysis between polysaccharides and amino acids or peptides smaller than 8000 Da.

Chymotrypsin↗