NanoLab August 2003 Nanoscale motors Molecular Motors Biological
Nano-Lab August 2003 Nano-scale motors
Molecular Motors Ø Biological Motors Ø Ø Laboratory made motors Ø Ø Background Ø Three types of linear stepper protein motors Linear stepper motor: Kinesin Rotary propellers: bacterial flagella UC Berkeley University of Edinburgh/Bologna Cornell/UCLA Future Projections
Background n n Molecular motors are proteins that use ATP to carry out coordinated movements within cells. ATP hydrolysis is presumed to drive protein conformation changes that result in sliding or walking movements. Molecular movement occurs along a “track” The “track”, either an actin filament or a micro tubule, is a helical polymer that has intrinsic polarity. http: //courses. nnu. edu/cm 342 jc/Term%20 Projects/2001%20 proj/collins. ppt
Linear Protein Motor Types MYOSIN Moves toward fast-growing (+) end of actin filaments. KINESIN DYNEIN Moves generally toward Moves toward slow-growing (-) end of microtubules. (+) end of microtubules. http: //courses. nnu. edu/cm 342 jc/Term%20 Projects/2001%20 proj/collins. ppt
Kinesin ~80Å n n (Vale & Milligan, 2000) Kinesin “walks” along the microtubule (MT) protofilament, stepping from one tubulin subunit to the next. Unidirectional motion is produced by a pronounced conformational change in kinesin’s “neck linker. ” http: //courses. nnu. edu/cm 342 jc/Term%20 Projects/2001%20 proj/collins. ppt
1. ) ATP binds to leading head, initiating docking of neck linker to tubulin. COILED COl. L: extends toward cargo. NECK LINKER: motion is produced by conformational change. http: //courses. nnu. edu/cm 342 jc/Term%20 Projects/2001%20 proj/collins. ppt CATALYTIC CORE: allosteric domain containing MT and nucleotide binding regions.
Bacterial Flagella n n Molecular engine powered by the flow of ions across the inner, or cytoplasmic, membrane of a bacterial cell envelope Each motor drives a protruding helical filament, and the rotating filaments provide the propulsive force for cells to swim. Artistic version of flagella motor http: //www 2. physics. ox. ac. uk/biophysics/research/flagellar. html
Bacterial Flagella n n n Ion flux is driven by an electrochemical gradient controlled by H+ and Na+ This gradient consists of a voltage component and a concentration component The inside of the cell is typically at an electrical potential about 150 m. V below the outside and has a slightly lower concentration of H+ or Na+ http: //www 2. physics. ox. ac. uk/biophysics/research/flagellar. html http: //www. id. ucsb. edu/fscf/library/battson/stasis/4. html
Bacterial Flagella n n n Filaments rotate at speeds up to 1000 Hz in swimming cells The rotating heart of the motor is a set of rings in the cytoplasmic membrane This rotor is surrounded by 8 -16 torque generators, proteins Mot. A and Mot. B, anchored in the cell wall http: //www 2. physics. ox. ac. uk/biophysics/research/flagellar. html
Laboratory Nano-motors UC Berkeley Gold Nano-motor n n Gold rotor on a multilayered Carbon nano-tube shaft The rotor, nano-tube anchors and stators were constructed around the carbon nano-tube, using electron beam lithography and silicon etching techniques, that had been deposited on a silicon wafer http: //www. berkeley. edu/news/media/releases/2003/07/23_motor. shtml
UC Berkeley Gold Nano-motor n n n Using an electric jolt to jerk the rotor, the nested nano-tube outer walls were broken free allowing the rotor to spin on the nano-tube “bearings” Motor is about 500 nm across The rotor is between 100 and 300 nm long http: //www. berkeley. edu/news/media/releases/2003/07/23_motor. shtml
UCLA/Cornell University Carlo Montemagno n n n Nickel rotors about 700 nm long are attached to the shaft molecule Shaft is rotated by the six cylindrical structures and can be turned off or on by adding or removing zinc from the solution A histidine peptide allows the molecular motor to adhere to nanofabricated patterns of gold, copper or nickel Nanofabricated nickel post http: //www. news. cornell. edu/releases/sept 99/bio_nano_mechanical. hrs. html http: //www. sciam. com/article. cfm? article. ID=000988 D 5 -647 B-1 C 75 -9 B 81809 EC 588 EF 21&page. Number=2&cat. ID=4
University of Edinburgh/Bologna Two smaller rings move around the larger “cycle” ring n Light, heat or chemical stimuli drive the rings around the cycle by altering the properties of each chemically distinct site chemistry professor David A. Leigh University of Edinburgh n http: //www. chem. ed. ac. uk/leigh/ http: //pubs. acs. org/cen/topstory/8128 notw 9. html http: //www. nanotechweb. org/articles/news/2/7/9/1
http: //bionano. rutgers. edu/Mavroidis_Final_Report. pdf Future Projections
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