Above: a computer generated model of a protease. The binding cleft can be seen to the right.

The NCBE supplies a range of high-quality enzymes from Novozymes and DSM, exclusively for educational use.

We are pleased to add five new liquid enzyme products that are used in detergents, including an improved lipase, to our list. Also, for the first time, we offer a microbial catalase and Peelzym^®, a pectinase made specially for peeling citrus fruit.

HOW LONG CAN I STORE THEM FOR?

The concentrated enzyme solutions or powders come in re-sealable plastic bottles and are accompanied by detailed product specification sheets and full safety information. The data sheets describe industrial uses of the enzymes and provide important information regarding their stability, dosage rates and optimum working conditions. If stored in a refrigerator at 3-5 °C most of these enzymes will retain their declared activity for at least a year.

WHAT CONCENTRATION ARE THEY?

We are asked this question every week. For enzymes, 'concentration' is a fairly meaningless measurement: the activity of an enzyme depends upon many factors, such as the pH, the substrate being used and its concentration, whether co-factors or inhibitors are present, the temperature and so on.

Usually, in a school laboratory context, teachers will be interested in achieving results rapidly so that the work can be completed within, say, a single lesson. This means that the amount of enzyme product used will often be far greater than that which is typical in industry. For example, in industry, about 130 mL of Pectinex is used per tonne of apples to maximise juice extraction; in the classroom, 1 mL per 50 g of apple is normally used to obtain results within a 30-minute period.

In short, we cannot answer the question 'what concentration should I use?' Instead, we recommend that you study the data sheet provided and test the particular protocol you have in mind before attempting it with students.

Safety guidelines for practical work with enzymes in schools
can be found here.

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