|
For decades, a wall chart detailing living
organisms' metabolic pathways has been a fixture in many
classrooms and laboratories where biochemistry is taught. One of
the most popular of those charts first appeared 30 years
ago. Now its editor, Gerhard Michal, has produced a book
that summarizes metabolism (broadly defined) in graphical
and textual formats. The book retains the elegance of the
chart. Names of molecules are printed in a crisp, easy-to-read
font, and structural formulas are shown with exemplary clarity.
Color coding serves multiple purposes: to differentiate enzymes,
substrates, cofactors, and effector molecules; to indicate in
which group or groups of organisms a reaction has been
observed; and to distinguish enzymatic reactions from regulatory
effects.
The primary advantage of presenting this
information in book format is immediately apparent. A typical
metabolic chart covers about 2 m2; the book has a total surface
area nearly 10 times greater. The extra space is used to add
explanatory text to the figures and to include many topics not
covered by the traditional definition of metabolism. Examples
include replication, transcription, translation, reaction
mechanisms for proteolytic enzymes, and the role of chaperones in
protein folding. Illustrating these topics is not as straightforward
as delineating a metabolic pathway, but the author has done
an admirable job of designing figures that clarify these and
other aspects of biochemistry and complement the accompanying
text.
A potential deficiency of book format is the inability
to clearly show links between different realms of
metabolism: carbohydrate and amino acid pathways, for example.
The book overcomes this problem in two ways. A
diagrammatic overview of metabolism (with references to applicable
sections of the book) is printed inside its front cover, and key
compounds (pyruvate, for example) have a distinctive green background
to provide a visual link between pathways. (The author
compares this feature to the hyperlinks in an electronic
document.)
The book's index is comprehensive and useful.
Entries for "phenylketonuria" and "sickle cell anemia", for
example, lead to commendably concise summaries of these
hereditary diseases (and the relevant metabolic pathway, in the
former case). Looking up a specific molecule, however, is less
helpful. The listing for fumarate hydratase, a citric acid cycle
enzyme, directs the reader to the chapter on special bacterial
metabolism but not to the section on the citric acid cycle itself.
Literature references are included at the end of
each section and are mainly from the 1990s, but they could be
more useful. A long section on heme proteins, for example,
concludes with eight citations, but their titles are not
included, so it is impossible to determine what topic each one addresses.
This book will be most useful to those with a good
understanding of the fundamentals of biochemistry. Some of
the information it presents could easily confuse less
experienced readers. For example, it classifies selenocysteine as a
standard amino acid in a figure but not in the accompanying text.
In the diagram of anaerobic glycolysis, a double-headed
arrow for the hexokinase reaction reinforces the frustratingly
common student misperception that the phosphoryl group of
glucose-6-phosphate can be used to phosphorylate ADP.
Biochemical Pathways compiles a large amount of
information in a single source. Its good index and clear, concise
text and diagrams should make it a reliable way of gaining
insight into many biochemical topics. With a price similar to
that of most textbooks, it merits a place in the libraries of
individuals and academic departments that teach biochemistry.
|