Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.1 (chymotrypsin)
 10,938 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This work describes a methodology to monitor protein unfolding by using the well known changes in tyrosine absorbance with the ionization of the side chain phenol group. It can be applied to proteins that are functionally active at pH values higher than 9.0 where the current UV differential spectroscopy technique can not be used. The simplicity and facility of the proposed methodology (only two absorbance measurements have to be acquired) can make it very useful namely for technological applications. Thermal unfolding of cutinase and alpha-chymotrypsin were followed using this methodology and the thermodynamic stability data were obtained assuming a two-state mechanism. The transition from the folded to the unfolded state was further confirmed by fluorescence maxima for both proteins proving the validity of the methodology based on UV measurements.
 ...
PMID:Thermal unfolding of proteins at high pH range studied by UV absorbance. 908 83

The abilities of isolates of saprophytes (Neurospora crassa, Aspergillus nidulans), an opportunistic human pathogen (Aspergillus fumigatus), an opportunistic insect pathogen (Aspergillus flavus), plant pathogens (Verticillium albo-atrum, Verticillium dahliae, Nectria haematococca), a mushroom pathogen (Verticillium fungicola) and entomopathogens (Verticillium lecanii, Beauveria bassiana, Metarhizium anisopliae) to utilize plant cell walls and insect cuticle components in different nutrient media were compared. The pathogens showed enzymic adaptation to the polymers present in the integuments of their particular hosts. Thus, the plant pathogens produced high levels of enzymes capable of degrading pectic polysaccharides, cellulose and xylan, as well as cutinase substrate, but secreted little or no chitinase and showed no proteolytic activity against elastin and mucin. The entomopathogens and V. fungicola degraded a broad spectrum of proteins (including elastin and mucin) but, except for chitinase, cellulase (V. lecanii and V. fungicola only) and cutinase (B. bassiana only), produced very low levels of polysaccharidases. The saprophytes (Neu. crassa and A. nidulans) and the opportunistic pathogens (A. fumigatus and A. flavus) produced the broadest spectrum of protein and polysaccharide degrading enzymes, indicative of their less specialized nutritional status. V. lecanii and V. albo-atrum were compared in more detail to identity factors that distinguish plant and insect pathogens. V. albo-atrum, but not V. lecanii, grew well on different plant cell wall components. The major class of proteases produced in different media by isolates of V. albo-atrum and V. dahliae were broad spectrum basic (pI > 10) trypsins which degrade Z-AA-AA-Arg-NA substrates (Z, benzoyl; AA, various amino acids; Na, nitroanilide), hide protein azure and insect (Manduca sexta) cuticles. Analogous peptidases were produced by isolates of V. lecanii and V. fungicola but they were specific for Z-Phe-Val-Arg-NA. V. albo-atrum and V. dahliae also produced low levels of neutral (pI ca 7) and basic (pI ca 9.5) subtilisin-like proteases active against a chymotrypsin substrate (Succinyl-Ala2-Pro-Phe-NA) and insect cuticle. In contrast, subtilisins comprised the major protease component secreted by V. lecanii and V. fungicola. Both V. lecanii and V. albo-atrum produced the highest levels of subtilisin and trypsin-like activities during growth on collagen or insect cuticle. Results are discussed in terms of the adaptation of fungi to the requirements of their ecological niches.
 ...
PMID:Adaptation of proteases and carbohydrates of saprophytic, phytopathogenic and entomopathogenic fungi to the requirements of their ecological niches. 920 74

A proteolytic enzyme, alpha-chymotrypsin, and a lipolytic enzyme, cutinase, were adsorbed from aqueous solution onto a hydrophobic Teflon surface and a hydrophilic silica surface. We investigated the influence of adsorption on the structure, the structure thermal stability and the activity of these enzymes. Probing the protein structure by circular dichroism spectroscopy indicates that Teflon promotes the formation of helical structure in alpha-chymotrypsin, but the reverse effect is found with cutinase. The perturbed protein structures on Teflon are remarkably stable, showing no heat-induced structural transitions up to 100°C, as monitored by differential scanning calorimetry. Contact with the hydrophilic silica surface leads to a loss in the helix content of both proteins. Differential scanning calorimetry points to a heterogeneous population of adsorbed protein molecules with respect to their conformational states. The fraction of the native-like conformation in the adsorbed layer increases with increasing coverage of the silica surface by the proteins. The specific enzymatic activity in the adsorbed state qualitatively correlates with the fraction of proteins in the native-like conformation.
 ...
PMID:Structure, Stability, and Activity of Adsorbed Enzymes 924 Nov 87

A proteolytic enzyme, alpha-chymotrypsin, and a lipolytic enzyme, cutinase, were adsorbed from aqueous solutions on solid surfaces with different hydrophobicities and morphologies. With both enzymes the affinity of adsorption is larger for the more hydrophobic surface. Water-soluble, flexible oligomers grafted on the sorbent surface cause a decrease in enzyme adsorption. CD spectroscopy and differential scanning calorimetry (DSC) indicate severe structural perturbations in the enzymes resulting from adsorption. The CD spectra reflect an average of the structure of the whole protein population. The DSC data allow additional conclusions to be drawn on the heterogeneity in the conformational states of the adsorbed enzymes. The degree of structural perturbation, that is the fraction of the adsorbed molecules of which the structure is perturbed, is lower at a surface that (1) is less hydrophobic, (2) contains water-soluble flexible oligomers and (3) is more covered by the protein. The specific activities of the enzymes are decreased on adsorption, more or less following the extent of structural perturbation. Unlike in solution, in the adsorbed state the heat-induced inactivation process is not identical with the heat-induced unfolding process. Furthermore, when the enzymes are adsorbed their specific activities are much less sensitive to temperature variation.
 ...
PMID:Surface-induced changes in the structure and activity of enzymes physically immobilized at solid/liquid interfaces. 975 64