PURPOSE The purpose was to characterize the properties of a proteinase activity associated with betaA3-crystallin, which was isolated from the alpha-crystallin fraction of human lenses. METHODS An inactive, Arg-bond hydrolyzing proteinase in the alpha-crystallin fraction, which was isolated from the water soluble (WS) protein fraction of 60- to 70-year-old human lenses, was activated by sodiu...

Severe acute respiratory syndrome (SARS) coronavirus is a novel human coronavirus and is responsible for SARS infection. SARS coronavirus 3C-like proteinase (SARS 3CL) plays key roles in viral replication and transcription and is an attractive target for anti-SARS drug discovery. In this report, we quantitatively characterized the dimerization features of the full-length and N-terminal residues...

The infective larvae of Necator americanus were shown to secrete all mechanistic classes of proteolytic enzymes with two overall pH optima of 6.5 and 8.5 using fluorescein isothiocyanate-labeled casein as the substrate. Since infective larvae are obligate skin penetrators, the effect of each of these enzyme classes against macromolecules derived from human skin was examined. Larval secretions w...

BACKGROUND Proteinase activities are often measured using chromogenic substrates that are much smaller than physiological substrates. METHODS The hydrodynamic size of macromolecular substrates (macrosubstrates) prepared by linking small chromogenic substrates to polyethylene glycol was determined by gel filtration. Efficiency of macrosubstrate cleavage by proteinases and alpha(2)-macroglobuli...

A protein proteinase inhibitor was purified from a seed extract of amaranth (Amaranthus hypochondriacus) by precipitation with (NH4)2SO4, gel-filtration chromatography, ion-exchange chromatography, and reverse-phase high-performance liquid chromatography. It is a 69-amino acid protein with a high content of valine, arginine, and glutamic acid, but lacking in methionine. The inhibitor has a rela...

2-fold. Lack of the vacuolar endoproteinases yscA and yscB reduces the protein degradation rate by about 30% under the conditions of canavanine-induced synthesis of false proteins (Table 2). The remaining protein degradation rate of 15% under starvation conditions, and of 6(r-70°h under growing conditions in mineral medium in strains defective in the two vacuolar endoproteinases yscA and yscB, ...

Erythrocytic malaria parasites degrade hemoglobin as a principal source of amino acids for parasite protein synthesis. We have previously shown that a Plasmodium falciparum trophozoite cysteine proteinase, now termed falcipain, is required for hemoglobin degradation, and we have hypothesized that this proteinase is responsible for initial cleavages of hemoglobin. To further evaluate the biologi...

The tumor microenvironment is replete with proteinases. As a sensor of proteinases, proteinase activated receptor 2 (PAR2) plays critical roles in tumorigenesis. We showed that PAR2 and its activating proteinase were coexpressed in different colon cancer cell lines, including HT29. Inactivating proteinase or knockdown of PAR2 significantly not only reduced cell proliferation in vitro but also i...

The ability of tumor cells to express elevated levels of proteinases capable of degrading tissue matrix and basement membrane components in vitro has been correlated to their invasive and metastatic potential. Many in vitro invasion assays have been performed either in the presence of serum or with tumor cells that had been previously grown in serum. Since serum contains large amounts of active...

Mast cells are usually located perivascularly and the granules contain an ionic complex of heparin, histamine and at least one proteinase. Heparin accelerates the reaction between thrombin and anti-thrombin 111, whereas histamine is a vasodilator and increases capillary permeability. The risk of clotting in the early stages of the inflammatory response to injury is thereby decreased. Although t...