Abstract:
:A recent thermodynamic model describes a reversible reaction between cholesterol (C) and phospholipid (P) to form a condensed complex C(nq)P(np). Here q and p are relatively prime integers used to define the stoichiometric composition, and n is a measure of cooperativity. The present study applies this model to the scanning calorimetry of binary mixtures of cholesterol and saturated phosphatidylcholines, especially work by McElhaney and collaborators. These mixtures generally show two heat capacity peaks, a sharp peak and a broad peak. The sharp heat absorption is largely due to the chain melting transition of pure phospholipid. In the present work the broad heat absorption is attributed to the thermal dissociation of complexes. The best fits of the model to the data require the complex formation to be highly cooperative, with cooperativity n = 12. Detailed comparisons are made between model calculations and calorimetric data. A number of unusual features of the data arise naturally in the model. The principal discrepancy between the calculations and experimental results is a spurious calculated heat absorption peak. This discrepancy is related to the reported relative magnitudes of the integrated broad and sharp heat absorption curves.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Anderson TG,McConnell HMdoi
10.1016/S0006-3495(01)75920-6subject
Has Abstractpub_date
2001-11-01 00:00:00pages
2774-85issue
5eissn
0006-3495issn
1542-0086pii
S0006-3495(01)75920-6journal_volume
81pub_type
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