Intact, metabolically active rumen protozoa prepared by gravity sedimentation and washing in a mineral solution at 10 to 15 degrees C had comparatively low proteolytic activity on azocasein and low endogenous proteolytic activity. Protozoa washed in 0.1 M potassium phosphate buffer (pH 6.8) at 4 degrees C and stored on ice autolysed when they were warmed to 39 degrees C. They also exhibited low...

turnover, but seems unlikely as proteinase 1 is probably lysosomal (North, 19826). Nor has it been shown that substrates and inhibitors used in these studies are specific for proteinase I, which raises the possibility that other proteinases might be involved. A role for cysteine proteinases in the selective control of turnover rates of specific proteins requires more thorough investigation. It ...

Two methods of measuring protein breakdown resulting from self-digestion during incubation in extracts of soybean leaves were examined. The release of free alpha-amino-nitrogen was measured with ninhydrin, and the disappearance of the large subunit of ribulose bisphosphate carboxylase (RuBPcase) was followed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Rates of protein breakd...

During acute lung inflammation, the airspaces are invaded by circulating neutrophils. These may then injure tissues through the release of elastase. Different natural specific inhibitors such as alpha1-proteinase inhibitor, secretory leukocyte proteinase inhibitor, and elafin are nonetheless able to counteract the enzymatic activity of elastase. The present study was undertaken to assess the ro...

Elastases in cystic fibrosis (CF) pulmonary fluids damage lung tissue and perpetuate cycles of infection, inflammation and injury. Elastases from three different sources may be present in CF airways: neutrophils, macrophages and Pseudomonas. We measured how well the cephalosporin-based antielastase L-658,758 blocks the activity of human neutrophil elastase (NE), human proteinase-3, human macrop...

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...

As molecularly targeted agents reach the clinic, there is a need for assays to detect their presence and effectiveness against target molecules in vivo. Proteinase inhibitors are one example of a class of therapeutic agent for which satisfactory methods of identifying successful target modulation in vivo are lacking. This is of particular importance while these drugs are in clinical trials beca...

The activity of multicatalytic proteinase against synthetic substrates and the kinetics of its inhibition by a range of class-specific inhibitors have been investigated. The enzyme was found to have a broader pH activity profile than previously noted, being active against succinyl-Ala-Ala-Phe-7-amino-4-methylcoumarin optimally at pH 4.5 and against benzyloxycarbonyl-Gly-Gly-Arg-7-amino-4-methyl...

In this study, the interaction between clozapine, an atypical antipsychotic drug, and alpha-2-macroglobulin (?2M), a multipurpose anti-proteinase, was investigated under simulated (patho) physiological conditions using multiple spectroscopic techniques molecular modeling. It found that ?2M binds clozapine with moderate affinity (the binding constant of 0.9 × 105 M?1 at 37 °C). The preferable si...