Characterisation of proteolytic activity of excretory-secretory products from adult Strongylus vulgaris.

The researchers are investigating the protein-breaking activity of substances released by the adult Strongylus vulgaris worm. They use different techniques to identify and isolate these enzymes and their activities.

Research Methodology

• The researchers started their experiments by creating what they called an excretory-secretory (ES) preparation. This ES preparation contained the substances, including enzymes, that the adult Strongylus vulgaris worm produces and releases.
• They then measured the ability of the ES preparation to break down proteins (protelytic activity) using azocasein (a derived form of casein, the primary protein found in milk) and synthetic peptides as substrates allowing the ES proteins to act upon.
• In order to separate the components of their ES sample, they used molecular sieve fast protein liquid chromatography (FPLC), which isolates proteins by size. They identified the active bands by using a technique known as gelatin-substrate sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE).
• The team also identified that an essential molecule called dithiothreitol (DTT), which is known to activate certain enzymes, considerably increased protein breakdown or proteolysis in their experiments. This indicated that the predominant proteases in their sample were likely to belong to a class of enzymes known as cysteine proteases, which require DTT for their activity.

Results

• After fractionating the ES preparation using FPLC and testing the fractions with the help of DTT, the researchers found a wide peak of activity that broke down the azocasein. They also found two peaks of activity from the use of synthetic substrates for their experiments.
• They found that the breakdown of the synthetic substrate Z-Phe-Arg-NMec was much higher than that of Z-Arg-Arg-NMec. This suggested that the proteases in these peaks were similar in specificity to certain proteases (papain or cathepsin L) rather than others (cathepsin B).
• When separating the proteins using the gelatin SDS-PAGE technique, DTT was again required to detect proteolysis. The team also found that the proteolysis was optimum at pH 6.0. Eight bands of various sizes were revealed through this method, further highlighting that there were several types of proteases present in the ES solution.
• They also found that cysteine proteinase inhibitors were most effective in stopping the proteolysis, confirming that the proteases belonged to the cysteine class of proteases predominant in the ES preparation of adult S. vulgaris.

This study provides valuable insights into the proteolytic activities of adult Strongylus vulgaris, which might be important for understanding the worm’s biology and potential development of new treatments for infections.