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208 Biomimetics: Biologically Inspired Technologies

Figure 7.5 The biological elements will be used to fabricate robotic systems. A vision of a nano-organism: carbon
nanotubes (CNT) form the main body; peptide limbs can be used for locomotion and object manipulation, a
biomolecular motor located at the head can propel the device in various environments.

production and dimensions of the molecular motors (Montemagno and Bachand, 1999; Bachand
and Montemagno, 2000; Soong et al., 2000). Frasch’s group is currently studying the binding
of metals to amino acids of the motor protein. These experiments are providing new insights into
the means by which the energy obtained from the hydrolysis of ATP can be converted into the
physical action of pumping a proton in a unilateral direction (Frasch, 2000).

7.2.2.2 Kinesin and Myosin

Motor proteins are tiny vehicles that transport molecular cargoes within cells. These minute cellular
machines exist in three families: the kinesins, the myosins, and the dyneins (Farrell et al., 2002).
Conventional kinesin was found to be a highly processive motor that could take several hundred
steps on a microtubule without detaching (Block et al., 1990; Howard et al., 1989), whereas muscle
myosin has been shown to execute a single ‘‘stroke’’ and then dissociate (Finer et al., 1994).
A detailed analysis and modeling of these motors has been done (Vale and Milligan, 2000).
Hackney’s group has concentrated upon the usage of ATP energy by motors like kinesin, myosin,
dynenin, and related motor families (Hackney, 1996). Unger’s group is currently working towards
developing a microtubule–kinesin system as a biological linear-motoric actuator. Their work is
aimed at producing force multiplication by parallel action of numerous single driving units as well
as a more efficient means for system control (Bohm et al., 1997). Other researchers have discovered
a new member of the myosin-V family (Myo5c) and have implicated this myosin in the transport of
a specific membrane compartment (Mehta et al., 1999). The role of ATP hydrolysis in kinesin
motility has also been recently described (Farrell et al., 2002).

7.2.2.3 The Flagella Motors
Escherichia coli and similar organisms are equipped with a set of rotary motors only 45 nm in
diameter. Each motor drives a long, thin, helical filament that extends several cell body lengths out