HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Walsh, M. T. Articles by Atkinson, D. Search for Related Content PubMed PubMed Citation Articles by Walsh, M. T. Articles by Atkinson, D. Social Bookmarking                      What's this?

Journal of Lipid Research, Vol 31, 1051-1062, Copyright © 1990 by Lipid Research, Inc.

ARTICLES

Calorimetric and spectroscopic investigation of the unfolding of human apolipoprotein B

MT Walsh and D Atkinson
Department of Biophysics, Housman Medical Research Center, Boston University School of Medicine, MA 02118-2394.

The unfolding of human apolipoprotein B-100 in its native lipid environment, low density lipoprotein (LDL), and in a soluble, lipid- free complex with sodium deoxycholate (NaDC) has been examined using differential scanning calorimetry (DSC) and near UV circular dichroic (CD) spectroscopy. High resolution DSC shows that LDL undergoes three thermal transitions. The first is reversible and corresponds to the order-disorder transition of the core-located cholesteryl esters (CE) (Tm = 31.1 degrees C, delta H = 0.75 cal/g CE). The second, previously unreported, is reversible with heating up to 65 degrees C (Tm = 57.1 degrees C, delta H = 0.20 cal/g apoB) and coincides with a reversible change in the tertiary structure of apoB as shown by near UV-CD. No alteration in the secondary structure of apoB is observed over this temperature range. The third transition is irreversible (Tm = 73.5 degrees C, delta H = 0.99 cal/g apoB) and coincides with disruption of the LDL particle and denaturation of apoB. The ratio of delta H/delta HvH for the reversible protein-related transition suggests that this is a two-state event that correlates with a change in the overall tertiary structure of the entire apoB molecule. The second protein-related transition is complex and coincides with irreversible denaturation. ApoB solubilized in NaDC undergoes three thermal transitions. The first two are reversible (Tm = 49.7 degrees C, delta H = 1.13 cal/g apoB; Tm = 56.4 degrees C, delta H = 2.55 cal/g apoB, respectively) and coincide with alterations in both secondary and tertiary structure of apoB. The changes in secondary structure reflect an increase in random coil conformation with a concomitant decrease in beta-structure, while the change in tertiary structure suggests that the conformation of the disulfide bonds is altered. The third transition is irreversible (Tm = 66.6 degrees C, delta H = 0.54 cal/g apoB) and coincides with complete denaturation of apoB and disruption of the NaDC micelle. The ratio of delta H/delta HvH for the two reversible transitions indicates that each of these transitions is complex which may suggest that several regions or domains of apoB are involved in each thermal event.
CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				A. Johs, M. Hammel, I. Waldner, R. P. May, P. Laggner, and R. Prassl Modular Structure of Solubilized Human Apolipoprotein B-100: LOW RESOLUTION MODEL REVEALED BY SMALL ANGLE NEUTRON SCATTERING J. Biol. Chem., July 14, 2006; 281(28): 19732 - 19739. [Abstract] [Full Text] [PDF]

				L. Wang, M. T. Walsh, and D. M. Small Apolipoprotein B is conformationally flexible but anchored at a triolein/water interface: A possible model for lipoprotein surfaces PNAS, May 2, 2006; 103(18): 6871 - 6876. [Abstract] [Full Text] [PDF]

				C. M. Chung, J. D. Chiu, L. H. Connors, O. Gursky, A. Lim, A. B. Dykstra, J. Liepnieks, M. D. Benson, C. E. Costello, M. Skinner, et al. Thermodynamic Stability of a {kappa}I Immunoglobulin Light Chain: Relevance to Multiple Myeloma Biophys. J., June 1, 2005; 88(6): 4232 - 4242. [Abstract] [Full Text] [PDF]

				D. L. Gantz, M. T. Walsh, and D. M. Small Morphology of sodium deoxycholate-solubilized apolipoprotein B-100 using negative stain and vitreous ice electron microscopy J. Lipid Res., September 1, 2000; 41(9): 1464 - 1472. [Abstract] [Full Text]

				S. Bauelos, J. L. R. Arrondo, Fél. M. Goi, and G. Pifat Surface-Core Relationships in Human Low Density Lipoprotein as Studied by Infrared Spectroscopy J. Biol. Chem., April 21, 1995; 270(16): 9192 - 9196. [Abstract] [Full Text] [PDF]