In the lab topic you investigate the activity of the enzyme amylase, a carbohydr

Question

In the lab topic you investigate the activity of the enzyme amylase, a carbohydrate-digesting enzyme found in the digestive tract of many animals. Other digestive enzymes in animal’s digestive tracts include those that digest proteins, proteases. Although we usually think of protein- digesting enzymes as being found in the digestive tract of animals, it is interesting to note that plants also contain proteases. For example, pineapple fruits and stems contain the protease bromelain, and the fruit of papaya contains the protease papain. Both of these enzymes are reported to have health benefits, and papain is used in meat tenderizers, for example, Adolph’s Meat Tenderizer.

Using protocols and materials presented in the lab topic, design an experiment to investigate the activity of one of these enzymes. What is the optimum pH for this activity? At what temperature is it denatures? Does it digest a range of common proteins, for examples, gelatin or albumin?

Explanation / Answer

Papain shows its optimal high activity at pH 5.0 and can digest 300 times more than its weight of egg albumin. It can also function in neutral and alkaline media. It is completely soluble in water and glycerol but is insoluble in organic solvents. Papain is a cysteine protease and is a relatively heat resistant enzyme, with a temperature optimal range of 60-70 °C. Papain consists of several proteolytic enzymes like peptidase-I, milk coagulating enzyme like rennin, amylolytic enzyme and a clotting enzyme similar to pectase. Peptidase - I can convert proteins into dipeptides and polypeptides.

Bromelin is a glycoprotein and insoluble in water. It is acidic in nature in fruit and alkaline in stem tissues. It contains endopeptidases like ananain and comosain. It is used as a meat tenderizer. It has the optimum temperature for maximum cumulated activity over time is 35-45 °C and survive at room temperature for one week under freeze thawed condition.

To test optimum pH and temperature and digesting ability of other proteins like albumin or geatin, the enzyme extracts are tested at various concentrations with albumin and gelatin and measure the inhibitory activity. The pH and temperature range cn be known by incubating enzyme preparation at various pH and temperatures range and the residual concentration of enzyme measured before and after the incubation and optimum pH and temperature can be known.

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