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Features Section: Problem-based Learning

Editor: C A Smith, The Manchester Metropolitan University, UK

The Problem-based Learning in this issue of Biochemical Education has two offerings. The first relates to the teaching enzyme kinetics, while the second concerns the use of PBL in teaching basic Biochemistry to medical students.

Enzymes have always fascinated me, even before my undergraduate days (themselves many years ago). It always appeared axiomatic that life was not possible without these splendid catalysts and therefore that they are intrinsically worthy of study. Thus it came as something of a shock to discover that some of my fellow students did not appreciate their activities, found their study boring and, indeed, a number of classmates positively detested learning/memorising those aspects of enzyme kinetics that were required in order to pass the unit examination! My subsequent experiences as a teacher suggest that, if anything, these attitudes in a number of students have hardened in over the intervening decades.

A quick perusal of any biochemistry textbook or past issues of this journal will reveal a wealth of material devoted to the structure, activities, modifications and biological roles of enzymes. A rapid scan of several standard (excellent) biochemistry texts 1-4 shows they devote considerable numbers of pages to enzyme kinetics reflecting the importance in which the topic is held. Why should, therefore, a significant proportion of students display this antagonism to the study of enzyme kinetics? True, the presentation of enzyme kinetics is often couched in mathematical terms and students, and many staff, find this approach difficult and/or obtuse. Perhaps texts should be more careful to explain the mathematics of the approach not only in simple (not simplistic), under- standable terms, but also at a pace which the reader can assimilate easily.

It is always necessary to justify why a subject requires study; to pass the examination is perhaps insufficient! I believe an understanding of enzyme kinetics is necessary in all students of the biological sciences. Kinetics can give value insights into the mechanism of action of the enzyme. This is particularly so, when combined with information from other techniques, such as the chemical or site- directed mutagenic modifications of essential active site residues, and structural studies of enzyme molecules, enzyme-substrate and enzyme-inhibitor/activator com- plexes. Enzyme kinetic experiments under appropriate conditions may also provide valuable inferences on the role(s) of the enzyme in the organism and on how its activities are regulated in response to metabolic needs. A knowledge of enzyme kinetics has practical aspects and may be exploited to manipulate metabolic and clinical conditions in, for example, the rational design of enzyme inhibitors for use as pharmaceutical agents.

BIOCHEMICAL EDUCATION 25(3) 1997

Having justified the study of kinetics to students, how can one get over the principles? The 'obvious' answer is the tried and trusted techniques: practice at solving problems, designing and performing experiments and analysing the data; and, dare one say, the PBL approach in addition to traditional teaching strategies. All too often, students are required to solve numerical questions and obtain the Michaelis-Menten constant of the enzyme, the maximum velocity of the reaction and identify the type of inhibition from their experimental data using the tried, if not entirely trusted, Lineweaver-Burk graphical method. In the past, I had little against this graphical approach in students fresh to the topic. I appreciate that the method introduces bias in favour of the lower concentration of substrate, but as a teaching aid it has the great advantage of placing the two variables on separate axes and so giving a less confusing picture to the student. However, in this age of small desk-top computers, I do believe all students should fit simple kinetic data to one of the freely available curve fitting programs, similar to those described in refer- ences 5'6. However, Dr. Whiteley in this issue of the PBL Page of Biochemical Education describes an interesting, but less well known way of graphically analysing enzyme data to obtain kinetic parameters and to identify the types of inhibition. This type of analysis deserves to be adver- tised and, as always, teachers of the molecular and cellular sciences can adapt the approach to their own needs.

The second article of the Page by Harris et al, is an account of the use of PBL in teaching aspects of basic Biochemistry to medical students at the West Virginia University School of Medicine. The experiences of these educators in designing and implementing an integrated PBL experience for their first year medical students is interesting and instructive. Everybody seems to have benefited and, no doubt, a follow-up article will be forth- coming when the first cohort of students begin their clinical clerkships in three years time!

My usual ending! The Problem-based Learning Page is always pleased to receive letters, so do write to express your views on the issues and topics raised here. Do keep submitting articles, especially those on topics/techniques less well described in the literature.

References 1 Matthews, C K and van Holde, K E (1990) Biochemistry, Benjamin/

Cummings, CA, USA 2 Stryer, L (1995) Biochemistry, 4th ed, W.H. Freeman and Co, NY,

USA 3 Voet D and Voet J G (1995) Biochemistry, 2nd ed, J Wiley & Sons, NJ,

USA 4 Zubay, G (1993) Biochemistry, 3rd ed, Wm C Brown, IA, USA 5 Beynon, R J (1985) CABIOS, 1, 111-5 6 Leone, F A, Baranauskas, J A and Ciancaglini, P (1995) Biochem Educ,

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