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By introducing cysteines at locations where bacteriophage T4 lysozyme molecules contact each other in a crystal and taking advantage of the alignment provided by the lattice, we have obtained polymers of defined polarity up to 25 molecules long that retain enzymatic activity. These polymers then were manipulated mechanically by using a modified scanning force microscope to characterize the force-induced reversible unfolding of the individual lysozyme molecules. This approach should be general and adaptable to many other proteins with known crystal structures. For T4 lysozyme, the force required to unfold the monomers was 64 \u00b1 16 pN at the pulling speed used. Refolding occurred within 1 sec of relaxation with an efficiency close to 100%. Analysis of the force versus extension curves suggests that the mechanical unfolding transition follows a two-state model. The unfolding forces determined in 1 M guanidine hydrochloride indicate that in these conditions the activation barrier for unfolding is reduced by 2 kcal\/mol.<\/jats:p>","DOI":"10.1073\/pnas.97.1.139","type":"journal-article","created":{"date-parts":[[2002,7,26]],"date-time":"2002-07-26T14:40:52Z","timestamp":1027694452000},"page":"139-144","update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":209,"title":["Solid-state synthesis and mechanical unfolding of polymers of T4 lysozyme"],"prefix":"10.1073","volume":"97","author":[{"given":"Guoliang","family":"Yang","sequence":"first","affiliation":[{"name":"Departments of Molecular and Cell Biology and Physics, University of California, Berkeley, CA 94720; Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720; Institute of Molecular Biology, Howard Hughes Medical Institute, and Department of Chemistry, University of Oregon, Eugene, OR 97403; Max-Planck-Institute for Molecular Physiology, Department of Structural Biology, Otto-Hahn-Str. 11, 44227 Dortmund, Germany; and Nutri-Logics, Inc., 111 SW Columbia Street, Suite..."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ciro","family":"Cecconi","sequence":"additional","affiliation":[{"name":"Departments of Molecular and Cell Biology and Physics, University of California, Berkeley, CA 94720; Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720; Institute of Molecular Biology, Howard Hughes Medical Institute, and Department of Chemistry, University of Oregon, Eugene, OR 97403; Max-Planck-Institute for Molecular Physiology, Department of Structural Biology, Otto-Hahn-Str. 11, 44227 Dortmund, Germany; and Nutri-Logics, Inc., 111 SW Columbia Street, Suite..."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Walter A.","family":"Baase","sequence":"additional","affiliation":[{"name":"Departments of Molecular and 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Department of Structural Biology, Otto-Hahn-Str. 11, 44227 Dortmund, Germany; and Nutri-Logics, Inc., 111 SW Columbia Street, Suite..."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Wendy A.","family":"Breyer","sequence":"additional","affiliation":[{"name":"Departments of Molecular and Cell Biology and Physics, University of California, Berkeley, CA 94720; Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720; Institute of Molecular Biology, Howard Hughes Medical Institute, and Department of Chemistry, University of Oregon, Eugene, OR 97403; Max-Planck-Institute for Molecular Physiology, Department of Structural Biology, Otto-Hahn-Str. 11, 44227 Dortmund, Germany; and Nutri-Logics, Inc., 111 SW Columbia Street, Suite..."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Julie A.","family":"Haack","sequence":"additional","affiliation":[{"name":"Departments of Molecular and Cell Biology and Physics, University of California, Berkeley, CA 94720; Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720; Institute of Molecular Biology, Howard Hughes Medical Institute, and Department of Chemistry, University of Oregon, Eugene, OR 97403; Max-Planck-Institute for Molecular Physiology, Department of Structural Biology, Otto-Hahn-Str. 11, 44227 Dortmund, Germany; and Nutri-Logics, Inc., 111 SW Columbia Street, Suite..."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Brian W.","family":"Matthews","sequence":"additional","affiliation":[{"name":"Departments of Molecular and Cell Biology and Physics, University of California, Berkeley, CA 94720; Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720; Institute of Molecular Biology, Howard Hughes Medical Institute, and Department of Chemistry, University of Oregon, Eugene, OR 97403; Max-Planck-Institute for Molecular Physiology, Department of Structural Biology, Otto-Hahn-Str. 11, 44227 Dortmund, Germany; and Nutri-Logics, Inc., 111 SW Columbia Street, Suite..."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Frederick W.","family":"Dahlquist","sequence":"additional","affiliation":[{"name":"Departments of Molecular and Cell Biology and Physics, University of California, Berkeley, CA 94720; Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720; Institute of Molecular Biology, Howard Hughes Medical Institute, and Department of Chemistry, University of Oregon, Eugene, OR 97403; Max-Planck-Institute for Molecular Physiology, Department of Structural Biology, Otto-Hahn-Str. 11, 44227 Dortmund, Germany; and Nutri-Logics, Inc., 111 SW Columbia Street, Suite..."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Carlos","family":"Bustamante","sequence":"additional","affiliation":[{"name":"Departments of Molecular and Cell Biology and Physics, University of California, Berkeley, CA 94720; 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