Transfer of oleic acid between albumin and phospholipid vesicles

Journal Article · Wed Jan 01 00:00:00 EST 1986 · Proc. Natl. Acad. Sci. U.S.A.; (United States)

DOI:https://doi.org/10.1073/pnas.83.1.82· OSTI ID:6154135

Hamilton, J A; Cistola, D P

The net transfer of oleic acid between egg phosphatidylcholine unilamellar vesicles and bovine serum albumin has been monitored by TC NMR spectroscopy and 90% isotopically substituted (1- TC)oleic acid. The carboxyl chemical shifts of oleic acid bound to albumin were different from those for oleic acid in phospholipid vesicles. Therefore, in mixtures of donor particles, the equilibrium distribution of oleic acid was determined from chemical shift and peak intensity data without separation of donor and acceptor particles. In a system containing equal masses of albumin and phospholipid and a stoichiometry of 4-5 mol of oleic acid per mol of albumin, the oleic acid distribution was pH dependent, with greater than or equal to80% of the oleic acid associated with albumin at pH 7.4; association was greater than or equal to90% at pH 8.0. Decreasing the pH below 7.4 markedly decreased the proportion of fatty acid bound to albumin. The distribution was reversible with pH and was independent of whether vesicles or albumin acted as a donor. These data suggest that pH may strongly influence the partitioning of fatty acid between cellular membranes and albumin. The TC NMR method is also advantageous because it provides information about the structural environments of oleic acid bound to albumin or phospholipid, the ionization state of oleic acid in each environment, and the structural integrity of the vesicles. In addition, minimum and maximum limits for the exchange rates of oleic acid among different environments were obtained from the NMR data.

• Research Organization: Boston Univ. School of Medicine, MA
• OSTI ID: 6154135
• Journal Information: Proc. Natl. Acad. Sci. U.S.A.; (United States), Vol. 83:1
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
ALBUMINS
NUCLEAR MAGNETIC RESONANCE
CELL MEMBRANES
OLEIC ACID
MASS TRANSFER
CARBON 13
CHEMICAL SHIFT
LABELLED COMPOUNDS
NMR SPECTRA
PH VALUE
PHOSPHOLIPIDS
STOICHIOMETRY
CARBON ISOTOPES
CARBOXYLIC ACIDS
CELL CONSTITUENTS
ESTERS
EVEN-ODD NUCLEI
ISOTOPES
LIGHT NUCLEI
LIPIDS
MAGNETIC RESONANCE
MEMBRANES
MONOCARBOXYLIC ACIDS
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PROTEINS
RESONANCE
SPECTRA
STABLE ISOTOPES
550601* - Medicine- Unsealed Radionuclides in Diagnostics