Improving Thai students' understanding of concepts in protein purification

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To support student learning in biochemistry and related courses, a simulation program, the Protein Purification Program, offers an alternative multimedia-based tool. This program has now been translated to produce a Thai version. However, translation from the original into the Thai language is limited by the differences between the language characteristics of English and Thai. Therefore, use of the program with Thai students had a twofold purpose. It helped their understanding of the concepts of protein purification by allowing code switching between the languages, but it also improved their understanding of, and competence in scientific English, which is a vital skill for functioning as a modern biochemist. According to the results of the questionnaires, undergraduates using the Thai/English program scored significantly higher than those using only the English language program (p<0.05). In addition, the interview data suggested that the Thai/English program had improved student understanding of the concepts of protein purification to a greater extent than a single language (English) program. Students' overall preference in terms of their learning using the Thai/English program was 4.15 on a 1–5 Likert scale.

Purifying proteins from complex mixtures is an important technique in biochemistry. A cell homogenate, for example, contains thousands of different proteins as well as nucleic acids and polysaccharides. Usually, the physical properties of a desired protein are unknown, and so a purification strategy has to be worked out largely by trial and error. In fact, purifying a protein may take several days in the laboratory (or even longer) and can be expensive in terms of materials used. Teaching undergraduate students how to purify proteins usually takes the form of lectures on methods along with perhaps one real, but recipe-style, laboratory practical class. Therefore,a computer simulation program has a number of advantages, including saving time and cost compared with lab work, encouraging systematic thinking,and practice. The two-language program also helps students' appreciation of English scientific terms.

The Java version of Protein Purification Program was written several years ago in English by Booth as an educational aid for undergraduate biochemistry students. The program contains information on 21 proteins, mostly on their physical properties, which provide the basis for their separation from a mixture. These properties (taken from the scientific literature) include their heat stability, precipitability with ammonium sulfate, the charge on the molecule, and the molecular weight.

Students are required to select one protein, which is then given an enzymatic activity by the program, and to “purify it” from a mixture of 21 proteins using the typical methods available,i.e., heat denaturation, ammonium sulfate precipitation, ion-exchange chromatography, gel filtration. They do not know the physical properties of the proteins at the outset. The computer makes the appropriate calculations and also “assays” the enzyme activity, so that the progress of purification can be followed. In addition, the computer can simulate one- and two-dimensional SDS electrophoresis gels as well as show immunoblotting with an appropriate antibody.

In practice in the School of Biochemistry at the University of Leeds, the purification simulation is posed to second-year undergraduate students of the biochemistry and related courses. It was always considered important that students had some background on protein purification from lectures (e.g., they should know what ion-exchange chromatography involves), and also have at least one lab experience of a protein purification procedure before they used the program. The rationale behind this was that they should have experience of the actual procedures and understand how long they take. The simulation could then help them to devise sensible strategies for purifications by trial and error. This would reinforce their learning of the methods used in protein purification. A feature of the program was that the operations are costed by the computer per unit of enzyme activity finally isolated; this put pressure on them to devise efficient strategies for purification.

In a typical step, a procedure is carried out and then the computer plots a graph showing the separation and also produces an assay of enzyme activity. Tubes from a column procedure can be pooled and subjected to gel electrophoresis to see how well the purification is proceeding. A purification table is simultaneously generated (but students can be asked to do this as part of the exercise).

The program can be used to reinforce the concepts about purification, but can also be used to illustrate practicalities. For example, one does wish to prepare 100% pure protein regardless of the yield as might be the case for a recombinant protein that is going to be used for human injection or obtain the maximal activity (number of units of enzyme) to some extent regardless of purity, such as might be the case for an enzyme that will be added to a detergent.