Approaching microtubule structure with the scanning tunneling microscope (STM)

We demonstrate that the scanning tunneling microscope can be used to obtain information about arrangement of tubulin subunits in the microtubule wall. Long rows of subunits with a periodicity of 3.8 +/- 0.4 nm were clearly visible in the images of microtubules. The separation between the rows of subunits was 4.8 +/- 0.4 nm. Close inspection of two images revealed another periodicity of 7.8 +/- 0.4 nm in the contour levels of the protofilaments. This indicates that alpha and beta tubulin monomers can be resolved. In these areas the monomers were arranged according to a ‘B-type’ lattice. Scanning tunneling microscope images confirm that the lateral contacts between tubulin monomers in adjacent protofilaments are compatible with a three-start, left-handed helix model. This study demonstrates that scanning tunneling microscopy can give direct information on the structure and organization of macromolecular assemblies and can complement the classical methods of electron microscopy and X-ray scattering.

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Scanning tunneling microscopy of E. coli RNA polymerase deposited onto an Au substrate by an electrochemical process

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100086192 ◽

1991 ◽

Vol 49 ◽

pp. 378-379

Author(s):

Rebecca W. Keller ◽

Carlos Bustamante ◽

David Bear

Keyword(s):

Scanning Tunneling Microscope ◽

Biological Sample ◽

Substrate Surface ◽

Electrochemical Process ◽

Atomic Resolution ◽

Scanning Tunneling ◽

Tunneling Microscopy ◽

Tunneling Microscope ◽

E Coli ◽

Preparation Techniques

Under ideal conditions, the Scanning Tunneling Microscope (STM) can create atomic resolution images of different kinds of samples. The STM can also be operated in a variety of non-vacuum environments. Because of its potentially high resolution and flexibility of operation, it is now being applied to image biological systems. Several groups have communicated the imaging of double and single stranded DNA.However, reproducibility is still the main problem with most STM results on biological samples. One source of irreproducibility is unreliable sample preparation techniques. Traditional deposition methods used in electron microscopy, such as glow discharge and spreading techniques, do not appear to work with STM. It seems that these techniques do not fix the biological sample strongly enough to the substrate surface. There is now evidence that there are strong forces between the STM tip and the sample and, unless the sample is strongly bound to the surface, it can be swept aside by the tip.

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EXAFS- and XANES-like spectra obtained by x-ray-excited scanning tunneling microscope tip current measurement

Surface and Interface Analysis ◽

10.1002/(sici)1096-9918(199903)27:3<132::aid-sia491>3.0.co;2-d ◽

1999 ◽

Vol 27 (3) ◽

pp. 132-135 ◽

Cited By ~ 13

Author(s):

Kouichi Tsuji ◽

Kazuaki Wagatsuma ◽

Kazuaki Sugiyama ◽

Kenji Hiraga ◽

Yoshio Waseda

Keyword(s):

Scanning Tunneling Microscope ◽

Current Measurement ◽

Scanning Tunneling ◽

Tunneling Microscope ◽

X Ray

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Spin-Polarized Scanning Tunneling Microscopy (SPSTM)

MRS Proceedings ◽

10.1557/proc-231-37 ◽

1991 ◽

Vol 231 ◽

Cited By ~ 4

Author(s):

R. Wiesendanger ◽

D. Buergler ◽

G. Tarrach ◽

I.V. Shvets ◽

H.-J. Guentherodt

Keyword(s):

Scanning Tunneling Microscope ◽

High Spatial Resolution ◽

Atomic Scale ◽

Scanning Tunneling ◽

Tunneling Microscopy ◽

Promising Technique ◽

Polarized Electrons ◽

Tunneling Microscope ◽

Magnetic Structures ◽

Spin Polarized

AbstractWe report on a novel promising technique for the investigation of magnetic structures at surfaces at high spatial resolution, ultimately down to the atomic scale. This technique is based on the observation of vacuum tunneling of spin-polarized electrons by means of a scanning tunneling microscope (STM). We discuss appropriate probe tips for the spin-polarized STM (SPSTM) and describe initial experimental results. We further focus on the information obtained by SPSTM. Finally, the perspectives of SPSTM will be discussed.

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