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dc.rights.licenseRestricted to current Rensselaer faculty, staff and students. Access inquiries may be directed to the Rensselaer Libraries.
dc.contributorKrause, Sonja
dc.contributorJohnson, William H.
dc.contributorEstes, James E.
dc.contributorWedler, Frederick C.
dc.contributor.authorDe Laney, Donald E.
dc.date.accessioned2021-11-03T08:19:49Z
dc.date.available2021-11-03T08:19:49Z
dc.date.created2015-04-10T16:08:27Z
dc.date.issued1975-12
dc.identifier.urihttps://hdl.handle.net/20.500.13015/1351
dc.descriptionDecember 1975
dc.descriptionSchool of Science
dc.description.abstractThe sizes of the molecules and of their aggregates were obtained from the field-free relaxation of the birefringence observed after the applied electric field was removed. The dipole moments of the paramyosin monomers were determined from their specific Kerr constants and from the ratio of the permanent to the induced dipole moments, P/Q, obtained from measurements in a reversing electrical field.
dc.description.abstractThe relaxation times of ɑ-R- and β-paramyosin at pH 3.1 measured over a temperature range of 20-S0°C showed no thermal denaturation for either form of the molecule.
dc.description.abstractAt the pH values above which the negatively birefringent species disappeared, i.e., pH 6.6 for β-paramyosin and pH 7.4 for ɑ-R-paramyosin, the two forms of the molecule behaved somewhat differently. At pH 7.4 the ɑ-R-paramyosin was monomeric while at pH 6.6 the β-paramyosin was in the form of small aggregates. However, as the pH was increased, both species of the molecule formed similar aggregates in equilibrium with monomer. It was concluded that aggregation in this region takes place in a stepwise manner, with the initial formation of a staggered dimer to which molecules add laterally, thus increasing the diameter while the length remains essentially constant. The relaxation time versus pH curves showed maxima for both forms of the molecule separated by about one pH unit: at pH 7.6-8.0 for β-paramyosin and at pH 8.8-9.2 for ɑ-R-paramyosin. The maximum relaxation times for both forms of the molecule were in the range of 80 ± 5 μsec which corresponds to the value expected for a heptamer. As the pH was increased, the relaxation times of both ɑ-R- and G-paramyosin decreased until only monomer was observed at pH 10. It was hypothesized that the shift to higher pH values for the maximum aggregation of ɑ-R-paramyosin relative to that of the β form is due to a difference in the number or environment of the basic residues that titrate in this region.
dc.description.abstractBirefringence measurements made on suspensions of paramyosin paracrystals indicated that the long axes of the molecules are in the same direction as the major axis of the paracrystals.
dc.description.abstractIn the region of pH 6-7.3 in the case of ɑ-R-paramyosin and pH 6-6.5 for β-paramyosin, a mixture of positively and negatively birefringent species was seen. It was concluded that the negatively birefringent signal probably originates from a large lateral aggregate of molecules in a form similar to an oblate spheroid. The positive signal is probably from monomer or small aggregates.
dc.description.abstractFrom the above observations it lias then hypothesized that ɑ-R-paramyosin has as an "extra piece" that is not present in β-paramyosin. At pH 3.1 this "extra piece" is probably in a rigid extended form due to the presence of an excess of charged basic residues which reveal themselves as part of the greater dipole moment on the ɑ-R-paramyosin at low pH. When this excess charge is neutralized by titration of carboxyl groups, the "extra piece" probably becomes more flexible and the molecule appears to have the same length as the β-paramyosin.
dc.description.abstractThe structure and aggregation properties of several forms of molluscan muscle paramyosin were studied over the pH range of 3 - 11 by the technique of transient electric birefringence. The paramyosin used in these studies was extracted from the white portion of the adductor muscles of the chowder clam, Mercenaria mercenaria. Reduced ɑ-paramyosin, which is thought to be the native form of the molecule, was isolated by an ethanol extraction procedure in the presence of .01M EDTA and 5mM dithiothreitol. Oxidized ɑ-paramyosin was prepared from the reduced protein by treatment with oxygen and CuC12. Another form of the molecule β-paramyosin, was obtained when EDTA and dithiothreitol were not included in the ethanol extraction procedure.
dc.description.abstractIt was found that at pH 3.1 the length of the monomeric ɑ-R-paramyosin (1220 ± 40 Å) is 5% greater than that of the β form of the molecule (1150 ± 20 Å) and that the dipole moments of these molecules are 6300 Debyes and 2700 Debyes, respectively. As the pH was increased, the apparent length of the ɑ-R-paramyosin decreased until it was the same as that of the β-paramyosin; the length of the latter remained unchanged over the same pH range. At pH 10, the monomeric ɑ-R- and β-paramyosin had the same length (1180 Å) and dipole moment (8400 Debyes).
dc.language.isoENG
dc.publisherRensselaer Polytechnic Institute, Troy, NY
dc.relation.ispartofRensselaer Theses and Dissertations Online Collection
dc.subjectChemistry
dc.titleThe structure and aggregation properties of paramyosin by transient electric birefringence
dc.typeElectronic thesis
dc.typeThesis
dc.digitool.pid174941
dc.digitool.pid174942
dc.digitool.pid174943
dc.rights.holderThis electronic version is a licensed copy owned by Rensselaer Polytechnic Institute, Troy, NY. Copyright of original work retained by author.
dc.description.degreePhD
dc.relation.departmentDept. of Chemistry


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