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Probing Biomaterials with the Atomic Force Microscope

Published online by Cambridge University Press:  02 July 2020

Helen G. Hansma ,
Christine Chen ,
Roxana Golan ,
Lia Pietrasanta ,
Cody Sorenson ,
Ilene Auerbach  and
Patricia Holden
Helen G. Hansma
Affiliation:
Department of Physics, University of California, Santa Barbara, CA93106
Christine Chen
Affiliation:
Department of Physics, University of California, Santa Barbara, CA93106
Roxana Golan
Affiliation:
Department of Physics, University of California, Santa Barbara, CA93106
Lia Pietrasanta
Affiliation:
Department of Physics, University of California, Santa Barbara, CA93106
Cody Sorenson
Affiliation:
Department of Physics, University of California, Santa Barbara, CA93106
Ilene Auerbach
Affiliation:
Department of Physics, University of California, Santa Barbara, CA93106 School of Environmental Science & Management, University of California, Santa Barbara, CA93106
Patricia Holden
Affiliation:
School of Environmental Science & Management, University of California, Santa Barbara, CA93106
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Extract

Recent AFM research in our laboratory has covered such diverse biomaterials as laminin and other macromolecules from basement membranes (Fig. 1) (1), DNA condensed for gene therapy (Fig. 2) (2), DNA-protein complexes in the yeast kinetochore (Fig. 3) (3), and biofilms of the bacterium Pseudomonas putida (Fig. 4) (4).

Laminin is a major protein of basement membranes. When analyzed by AFM in air, it shows a variety of conformations of its cruciform structure (Fig. 1A). Time-lapse images of a single laminin molecule in aqueous solution show the flexibility of the laminin arms as they move and bend (Fig. 1B)(1).

AFM analysis of DNA condensed for receptor-mediated gene therapy poses a puzzle (Fig. 2)(2). Polylysine condenses DNA poorly (Fig. 2A), while AsOR-polylysine condenses DNA into compact toroids and short rods (Fig. 2B). AsOR (asialoorosomucoid) is a 38-kDa glycoprotein with a net negative charge of 5 carboxylic acid groups per molecule. The puzzle is why this negative glycoprotein, covalently attached to polylysine, can enhance the condensation of DNA so much over the condensation caused by the polycation, polylysine, alone.

Type
Biological Applications of Scanning Probe Microscopies
Information
Microscopy and Microanalysis , Volume 5 , Issue S2: Proceedings: Microscopy & Microanalysis '99, Microscopy Society of America 57th Annual Meeting, Microbeam Analysis Society 33rd Annual Meeting, Portland, Oregon August 1-5, 1999 , August 1999 , pp. 1012 - 1013
Copyright
Copyright © Microscopy Society of America

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References

1. Chen, C. H., Clegg, D. O., and Hansma, H. G. (1998) Biochem. 37, 8262–8267.CrossRefGoogle Scholar

2. Hansma, H. G., Golan, R, Hsieh, W., Lollo, C. P., Mullen-Ley, P., and Kwoh, D. (1998) Nucleic Acids Res. 26, 2481–2487.CrossRefGoogle Scholar

3. Pietrasanta, L. I., Thrower, D., Hsieh, W., S., Rao, Stemmann, O., Lechner, J., Carbon, J., and Hansma, H. G. (1999) Proc. Natl. Acad. Sci. (USA), in press.Google Scholar

4. Hansma, H. G., Pietrasanta, L. L, Auerbach, I. D., Sorenson, C, Golan, R, and Holden, P. A. (1999) Polymer International, submitted.Google Scholar

5. Hansma, H. G., and Pietrasanta, L. (1998) Current Opinion in Chemical Biology 2, 579–584.CrossRefGoogle Scholar