Download Protein Structure and Enzyme Activity

COMPUTER SOFTWARE REVIEWS
Computer Software Reviews
Bioscience Software
IRL Press, Oxford1Washington,D. C., in association with the Biochemical Society, London, 1985
The programs reviewed are the first of a series of teaching
programs designed to run on the BBC Microcomputer.
They are all supplied on single-density 40/80 track singlesided discs; a special 80-track version is available for use
with ECONET level 2.
The packaging and presentation, in reinforced plastic
folders, are good. Each package includes the disc and one
copy each of the teacher’s notes and notes for students.
The disc enclosure is tight, such that removal without
bending is difficult. For this reason disc handling should be
entrusted to the teacher rather than the student. The initial
cost of each package is 222.50 (plus VAT) but additional
back-up discs may be purchased at g2.50 (plus VAT) each.
The publishers, understandably concerned to prevent
illegal copying of their software, have protected the discs,
each one having a serial number so that the source of any
pirated copies may be traced. The very moderate price of
back-up copies is a sensible move to make illegal copying
unnecessary. An order form is supplied with the package,
The notes provided are well produced and informative.
Additional copies of the notes for students can be ordered
at 21.50 each, a price which is rather excessive for a 12-page
booklet. The publishers should be encouraged to give a
substantial discount for bulk orders.
The programs are aimed mainly at A-level and first-year
undergraduate students, but could usefully be used on a
variety of courses at a variety of levels. Each program will
take the student between 30 and 60 minutes to complete.
Starting-up instructions are simple and clear and the programs are decidedly user-friendly. The use of a colour
monitor is essential. This may limit its use in schools since
evenon a high resolution monochrome monitor the contrast
is insufficient to distinguish the various shades adequately.
A. R. TAMMAR and P. E. SMITH
pH/Titrations
M. F. CHAPLIN
This program covers acid and base behaviour in the context
of titrations. The first section, though the sections may be
accessed in any order, deals with exponential scales and the
concept of pH. This is well covered and the student’s
understanding is tested with calculations for which a
scientific calculator is essential. This reviewer found having
to count up to 13 noughts on a small screen annoying.
The student’s booklet attempts to justify the use of decimal
notation but intended users would surely be sufficiently
numerate to cope with exponentials.
The next section deals with the concept of equilibrium
in kinetic rather than energetic terms. This approach
affords an excellent opportunity to exploit BBC graphics
to illustrate the attainment of equilibrium with a variety of
rate constants for association and dissociation. Further
sections extend these ideas to amino acids, at all times in
the context of ideal solutions. The titration section enables
curves to be drawn of any combination of strong and weak
acid and base with the user in control of the burette.
Indicator colours are also shown. The amphoteric nature of
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amino acids is demonstrated as well as the influence of the
R group.
The last part of the program permits selection of any
amino acid with a view to titrating it with NaOH from a
low pH. During the titration the structural formula changes
as appropriate protons are ionized, the pl is indicated and
so too is the resultant charge on the molecule. This reviewer
is not convinced that the sound effects are helpful but at
least they can be switched off. Most of the seven multiple
choice questions need a calculator and again it proved
impossible to input answers in scientific format. The
version issued was the one referred to in the teacher’s
booklet as having the unintelligible question 3. Minor
criticisms aside, this program provides a valuable insight
into how teachers may be made redundant as well as
affording a well-motivated student, with access t o the
equipment, an opportunity to become au fait with these
concepts. Most departments would find a copy a useful
addition to their teaching equipment.
A. R. TAMMAR
Protein Structure and Enzyme Activity
M. F. CHAPLIN
This program starts with amino acids, the structural information being much more detailed than in the pH/titration
program. Absolute configuration is not dealt with. Linking
of amino acids to form peptides is demonstrated although
the spatial characteristics of the peptide bond are only
hinted at. Further linking to form polypeptides and proteins
leads naturally to primary and secondary structure. Two
such structures, the anti-parallel 0-pleated sheet and the
&-helix, are well illustrated by animated building-up procedures, the particular strong-point of this teaching method.
The amount of detail would probably not satisfy a dedicated
proteinologist but the concepts are clearly presented.
Tertiary structure follows with examples of possible intramolecular bond types. The simulation of folding to form a
globular structure is perhaps the least satisfactory part of
this program.
The bulk of the program is concerned with enzyme
properties and seeks to demonstrate how enzyme-mediated
catalysis is affected by temperature, pH, substrate concentration, enzyme concentration and inhibitors. Two
approaches are used in conjunction. The top half of the
screen is occupied by graphs which show how the enzyme
would behave in the conditions chosen by the operator,
while the lower half simulates the supposed behaviour of
the molecules in animated cartoon form. This is very
successful, catering as it does for both the mathematical as
well as the more visually orientated students. The program
ends with an opportunity for the operator to alter more
than one variable at a time with a view to optimizing a
reaction rate (here the sound effects gave a useful aural
indication). Nine multiple choice questions finally test
the student’s grasp of the material presented. Again, this
program is recommended for departmental rather than
for individual purchase.
A. R. TAMMAR
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