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Molecular Motors. Edited by Manfred Schliwa

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further innovations in the future. That
comment also applies to the porphyrazines with annelated heterocyclic
rings that are the subject of the last article of Volume 15, and which contribute
essential information to the chemistry
of the macrotetracycle. Here, and also
in other parts of the handbook, there is
some overlapping between the contents
of individual articles, which is unavoidable in a work that consists of contributions from many different authors.
The subject of synthesis is usually
followed by that of spectroscopic characterization. For porphyrinoid macrocycles, with and without a central metal
atom, one also has to include the determination of redox properties by electrochemical methods. The five articles of
Volume 16 take into account the potential applications of phthalocyanines as
pigments for artificial photosynthesis,
as sensors, and as catalysts. They
describe in detail the characterization
of phthalocyanines by UV/Vis spectroscopy, by magnetic circular dichroism,
and by electrochemical and photoelectrochemical methods, as well as data
from quantum-mechanical calculations.
Unfortunately, many of the figures in
this volume leave something to be
desired, as they are not clearly drawn
or suffer from poor print quality.
The aggregation properties of phthalocyanines is a topic that has attracted
increasing interest, as this behavior
might offer the possibility of designing
new materials for various applications,
and Volume 17 contains five articles on
this theme. Different solid-state structures in phthalocyanines result in physical properties that form the basis for
applications as semiconductors, conductors, or materials with nonlinear optical
behavior, as discussed in the first article.
That is followed by articles on the formation of thin phthalocyanine films by
Langmuir–Blodgett techniques, on the
aggregation behavior of phthalocyanines in general, and on various relevant
methods of investigation and potential
applications. The properties of porphyrins, azaporphyrins, and phthalocyanines
can be used in the form of polymers by
attaching polymerizable groups to the
macrotetracycles and then incorporating them into suitable polymers. Such
polymers make it possible to immobilize
the catalytic or sensing functions of por-
5432
phyrins on solid supports, with the
advantage that such systems can be
used repeatedly in many cycles. The
last article of the volume describes how
a similar capability can be achieved by
the inclusion or intercalation of porphyrins or phthalocyanines into inorganic materials such as zeolites. Thus,
Volume 17 describes in detail the use
of macrotetracycles as materials or as
components of materials.
The common thread in the articles of
Volume 18 is the synthesis and properties of multiporphyrin and multiphthalocyanine structures, which are built up by
self-organization or by covalent bonding
of suitably functionalized macrocyclic
subunits. This theme also featured earlier at many places in Volumes 1–10,
for example, in connection with artificial
photosynthesis, but it is useful to have a
short survey of this area of research and
a progress report on these rapidly growing new developments. The last article in
this volume is also very interesting,
although the topic, that of new developments in corrin chemistry, does not fit
well into this volume, and would have
been better placed elsewhere in the
handbook.
The five articles of Volume 19 return
to the uses of phthalocyanines in medicine and as semiconductors, dyes, pigments, enzyme-like catalysts, and nonlinear optical materials, although some
applications in these areas were also
covered in Volumes 17 and 18. As a
result of that, there is some repetition
that could have been avoided by merging the articles.
Volume 20 consists of just one article, discussing the crystal structures of
phthalocyanines. The first half of the
article considers fundamental structural
aspects of phthalocyanines, and gives
an interesting overview of the topic
and useful insights. The second part
lists structural formulas and structural
data for phthalocyanines, in the same
way as was done previously for porphyrins in Volume 10 of the handbook. It
would certainly have been more helpful
to the user of the handbook to provide
this vast amount of data in electronic
form.
As one expects, Volume 20 also contains the cumulative index to Volumes 11–20, which is certainly very
useful. However, to make the entire
3 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
20-volume handbook really convenient
to use, it would be extremely useful to
provide an electronic index with the
additional facility of searching for keywords in combination. A good index is
an absolute necessity for accessing the
contents of a handbook, as the purpose
of such a work of reference is to
enable the user to extract information.
The merits of the handbook lie in the
fact that it provides the reader with firsthand access to the experts3 knowledge of
the many topics. However, that form of
presentation is also the source of the
work3s weaknesses, as it leads to overlapping, unbalanced weighting of different subject areas, or sometimes simply
losing the main guiding theme of the
work.
Franz-Peter Montforts
Institut fr Organische Chemie
Universitt Bremen (Germany)
Molecular Motors
Edited by Manfred
Schliwa. WileyVCH, Weinheim
2002. 582 pp.,
hardcover
E 169.00.—
ISBN 3-527-30594-7
The ability to generate directed motion
in the presence of the disruptive effects
of thermal motion is the remarkable
achievement of nature3s molecular
motors. The structural motifs in motor
proteins are tuned to deliver either
short strokes or processive walks. The
function of molecular motors has been
investigated using a plethora of experimental techniques: from genetic to
structural, from biochemical to biophysical, and from ensemble to single molecule. A basic understanding of these
motors has led to the present nanobiotechnological revolution and a desire
to harness molecular machines for medAngew. Chem. Int. Ed. 2004, 43, 5431 – 5435
Angewandte
Chemie
ical and technological purposes. At the
same time, the molecular basis of disease conditions, such as myosin myopathies and sensory defects, has been
found to involve mutations in motor
proteins that alter or destroy their
force-generating
properties.
The
research efforts in this area have been
truly multidisciplinary, so it would
seem an improbable (but not impossible) task to cover all these approaches
in a single book. The improbable has
been handsomely accomplished in a
new text appropriately entitled Molecular Motors (Wiley-VCH), edited by
Manfred Schliwa.
The text is sensibly organized, and
could be considered as five separate
books within a single, comprehensive
volume. It begins by covering the basic
principles of biomolecular motor
design, which includes an encyclopedic
listing of both classical and nonclassical
biological motors. The classical or conventional motors involved in muscle
contraction (myosin) and cellular transport/organization (kinesin and dynein),
are described, along with the nonconventional types of myosins and kinesins.
Nonclassical types include linear motors
(DNA and RNA polymerases and helicases) and rotary motors (the bacterial
flagellar motor and the F1 motor of
ATP synthase). These well-referenced
chapters include many useful diagrams
and figures, and a wealth of information
regarding function is provided in tables
that are easy to digest.
The mechano-chemistry of these
motors is discussed in the second part.
This includes a description of the new
technological developments used to
study the single-molecule mechanics of
linear and rotary motors. Here, possible
mechanisms are tested by asking: how
could a motor harness random thermal
fluctuations to generate directed
motion? The resulting theoretical analysis, using the power stroke (small
ratchet) and Brownian ratchet (big
ratchet) mechanisms as extreme examples, is particularly coherent. Where
mechanistic details remain controversial, both sides of an argument are
given equal treatment in these chapters.
However, two of the chapters in this part
present opposite sides of an ongoing
debate about how mechano-chemical
coupling occurs in myosin: is it tightly
Angew. Chem. Int. Ed. 2004, 43, 5431 – 5435
coupled (Chapter 11) or loosely coupled
(Chapter 13) to ATP hydrolysis? To
someone unfamiliar with this debate,
the presentation of both these two contrasting views as facts could be confusing. An unbiased explanation of both
views should perhaps have been presented in a single chapter.
The functional implications of these
biomolecular motors are discussed in
the third part, by re-introducing the
individual motors back into the biomachines from which they were
removed. The chapters consider the
functions of motors in mitotic spindles,
in generating developmental asymmetry, and in membrane trafficking, as
well as the regulation mechanisms used
to control motor function (motor
recruitment versus motor attenuation).
The final chapter in this part describes
the emerging research area of plant
motor proteins using Arabidopsis as a
model.
The fourth part is concerned with
the disease conditions that result when
motors go awry. Three chapters describe
the molecular basis for various myosin
myopathies, dynein-related axonemal
and developmental defects, and myosin
mutations that cause sensory defects.
This section provides the all-important
background and validation for the
experiments that biochemists and biophysicists like to do!
The final part summarizes attempts
to utilize nature3s motor designs, both
as basic building blocks and as design
inspiration, to create man-made molecular motors. These two chapters provide
a remedy (of a sort) for the “gray goo”
hysteria about nanotechnology, by
detailing the painstakingly small steps
that have been made towards developing the core technologies needed to
master assembly, energy transduction,
and control on the nanoscale. By combining biological and inorganic components into hybrid nanomachines, very
simple artificial nanodevices have been
constructed, none of which are yet
useful or mechanically robust. Several
huge engineering issues remain, many
of which require a better basic knowledge of biological motors and of how
to arrange them to produce useful outputs. Initial attempts to create proofof-principle artificial synthetic molecular motors (either light driven or chemiwww.angewandte.org
cally driven) have created linear motors
showing intramolecular translation
(molecular switches), and elegant
rotary motors showing unidirectional
intramolecular rotation. These motors
have not yet done any work, nor have
they been organized into nanomachines,
but they are the first steps towards functional nanotechnology. This final part
gives one a renewed appreciation of
the beautiful complexity of nature3s
motors, and of the challenges involved
in creating multifunctional nanomachines. However, as stated in the last
sentence of the final chapter, “Fighting
the Brownian motion, so elegantly
done by Nature3s molecular motors, is
a tantalizing goal”.
This compilation of 23 mini-reviewlike chapters from nearly 40 experts represents an extremely valuable guide (or
introduction for a non-expert) to the
current (early 2002) understanding of
molecular motor structure and function.
As the chapters are by different authors,
there are differences in writing style, and
some repetition also occurs. For example, the domain structure of dynein is
repeated several times in the chapters
that describe the molecular details of
dynein, the function of dynein in mitotic
spindles, and the axonemal defects arising from mutations in dynein. This
book is unlikely to be read from cover
to cover, rather it will be read one relevant section at a time. Minor repetition
under these circumstances could be
useful. Most chapters are well introduced, using graduate-level biological
or physical concepts, and new techniques are for the most part well
explained. The editor does not identify
a target audience for the work. I feel
that it is aimed at an advanced postgraduate audience, although some sections of the book would also be very
useful as introductory material in an
advanced undergraduate course. Personally, I found this book an enjoyable
and thought-provoking read—one to
be highly recommended to beginner
and specialist “motorheads” alike.
Christoph G. Baumann
Department of Biology, University of York
York (Great Britain)
DOI: 10.1002/anie.200485002
3 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
5433
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