Biomedical Engineering Reference
In-Depth Information
of. human. engineering. into. our. lives. has. been. the. introduction. of. motors. to. artiicially.
produce. motion. and. generate. a. capacity. to. perform. work.. The. semiconductor. industry,.
photovoltaics,. manufacturing,. and. modern. medicine. all. hope. to. achieve. goals. that.
in. some. aspects. have. already. been. mastered. by. nature. in. a. 3.5. billion-year. process. of.
evolution.. Biomimicry. or. biosynthetic. devices. that. incorporate. cellular. motors. offer. us.
unique.insights.into.perfected.design.strategies.at.the.nanoscale.for.novel.applications.in.
manufacturing,.biosensing,.and.medicine.(Hess.and.Vogel,.2001;.Dinu.et.al.,.2007;.Fischer.
et.al.,.2009;.Agarwal.and.Hess,.2010;.Subramanian.et.al.,.2010;.Hess,.2011).
Cellular. molecular. motors. are. present. in. a. range. of. shapes,. sizes,. and. capabilities.
dependent.on.the.mechanistic.need.and.can.be.considered.as.primarily.chemical,.nucleic.
acid,.or.protein-based.in.nature.(Vogel,.2005)..Chemical-based.motors.are.useful.as.one.of.
the.simplest.models.of.propulsion..Their.analysis.is.inspired.from.the.much.more.complex.
biomolecular. motor. proteins. of. the. cytoskeleton. in. living. cells. that. include. myosins,.
kinesins,.and.dynein..A.fundamentally.conserved.aspect.of.directed.motion.is.asymmetry..
In.a.chemical.system,.an.exothermic.reaction.that.is.asymmetrically.afiliated.can.be.used.
to.provide.a.mechanism.for.self-propulsion.(Shi.et.al.,.2009)..The.resulting.motion.can.be.
harnessed.in.engineered.systems.to.offer.an.alternative.or.additional.component.to.the.use.
of.biomolecular.motors..Specialized.polymers,.silicon,.or.chemical.fuels,.such.as.glucose,.
can.also.be.made.to.produce.work..Chemical.controls.and.the.concept.of.asymmetry.are.
often. imbedded. in. the. more. complex. protein. motors.. One. example. is. the. hydrolysis. of.
adenosine.triphosphate.(ATP).to.adenosine.diphosphate.(ADP).plus.an.inorganic.phosphate.
(Pi).that.occurs.at.the.catalytic.cores.of.biomolecular.motor.proteins..The.outcome.of.ATP.
binding.and.hydrolysis.on.protein.structure.are.conformational.changes.that.affect.track.
association.and.force.generation.or.motility..Interestingly,.the.outcome.of.ATP.binding.and.
hydrolysis. has. different. outcomes. for. kinesins. binding. to. microtubules. versus. myosins.
association. with. actin.. In. addition. to. chemical. or. cytoskeleton. protein. motors,. the. cell.
employs.a.diversity.of.other.motor.types.that.should.be.considered.in.designing.complex.
biosynthetic. devices.. The. well-studied. ribosome. machine. is. composed. of. both. RNA.
and. protein.. This. large. structure. includes. a. ratcheting. motor,. which,. like. a. ticker-tape.
machine,.helps.to.thread.a.single.mRNA.over.a.decoder.in.order.to.translate.this.into.a.
protein. sequence.. An. appreciation. of. multiple. motor. designs. is. helpful. in. engineering.
motor-based.nanosystems.for.speciic.applications.of.varying.complexity.
The. seemingly. endless. numbers. of. proteins. present. in. the. interior. of. a. biological. cell.
are. compartmentalized. to. structures. or. organelles. and. reside. in. a. complex,. interlinked.
network. necessary. to. manufacture. what. we. know. as.
life
.. The. very. powerful. nano-. and.
microscale.molecular.motors.that.self-assemble.de.novo.and.perform.their.duties.at.many.
locations.within.the.cellular.milieu.contribute.to.the.dynamic.nature.of.cellular.processes..
The.cytoskeleton.motor.protein.toolbox.in.each.cell.varies.among.species..In.eukaryotes,.
kinesin.and.myosin.are.multi-family.motor.proteins.and.appear.to.be.ubiquitous..Dynein,.
however,.is.not.universal,.which.suggests.that.cells.have.found.a.way.to.replace.its.functional.
roles..Multiple.families.exist.for.kinesin.and.myosin,.and.speciic.motor.parameters.can.
vary.between.families.including.form.(multimeric.or.multiprotein.complexes),.size,.speed,.
directionality,.processivity,.force.generation,.function,.and.location.(Lawrence.et.al.,.2004;.
De. La. Cruz. and. Ostap,. 2004;. O'Connell. et. al.,. 2007;. Wordeman,. 2005).. Motor. variations.
between. families. are. often. achieved. in. nature. through. the. use. of. specialized. domains.
that. allow. functional. tweaking. of. motor. protein. design.. Domains. are. deined. regions,.
often. functional. in. nature,. that. when. translocated. to. a. distinct. protein,. transfer. the.
deined.functional.capacity..Similarly,.the.need.to.redesign.motor.proteins.for.biosynthetic.
engineering. applications. is. important. to. consider.. This. necessitates. either. incorporating.
