New BODIPY lipid probes for fluorescence studies of membranes

Ivan A. Boldyrev, Xiuhong Zhai, Maureen M. Momsen, Howard L. Brockman, Rhoderick E Brown, Julian G. Molotkovsky

Research output: Contribution to journalArticle

63 Scopus citations

Abstract

Many fluorescent lipid probes tend to loop back to the membrane interface when attached to a lipid acyl chain rather than embedding deeply into the bilayer. To achieve maximum embedding of BODIPY (4,4-difluoro-4-bora-3a,4a- diaza-s-indacene) fluorophore into the bilayer apolar region, a series of sn-2 acyl-labeled phosphatidylcholines was synthesized bearing 4,4-difluoro-1,3,5,7- tetramethyl-4-bora-3a,4a-diaza-s-indacene-8-yl (Me4-BODIPY-8) at the end of C3-, C5-, C7-, or C9-acyl. A strategy was used of symmetrically dispersing the methyl groups at BODIPY ring positions 1, 3, 5, and 7 to decrease fluorophore polarity. Iodide quenching of the phosphatidylcholine probes in bilayer vesicles confirmed that the Me 4-BODIPY-8 fluorophore was embedded in the bilayer. Parallax analysis of Me4-BODIPY-8 fluorescence quenching by phosphatidyl-cholines containing iodide at different positions along the sn-2 acyl chain indicated that the penetration depth of Me4-BODIPY-8 into the bilayer was determined by the length of the linking acyl chain. Evaluation using monolayers showed minimal perturbation of <10 mol% probe in fluid-phase and cholesterol-enriched phosphatidylcholine. Spectral characterization in monolayers and bilayers confirmed the retention of many features of other BODIPY derivatives (i.e., absorption and emission wavelength maxima near 498 nm and ∼506-515 nm) but also showed the absence of the 620-630 nm peak associated with BODIPY dimer fluorescence and the presence of a 570 nm emission shoulder at high Me4-BODIPY-8 surface concentrations. We conclude that the new probes should have versatile utility in membrane studies, especially when precise location of the reporter group is needed.

Original languageEnglish (US)
Pages (from-to)1518-1532
Number of pages15
JournalJournal of Lipid Research
Volume48
Issue number7
DOIs
StatePublished - Jul 1 2007

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Keywords

  • 4,4-difluoro-4-bora-3a,4a- diazas-indacene
  • Fluorescence quenching
  • Fluorophore location in bilayers
  • Fluorophore position
  • Iodide
  • Lipid lateral packing
  • Lipid phase state
  • Monolayers
  • Parallax analysis
  • Spectral properties
  • Surface compressional modulus

Cite this

Boldyrev, I. A., Zhai, X., Momsen, M. M., Brockman, H. L., Brown, R. E., & Molotkovsky, J. G. (2007). New BODIPY lipid probes for fluorescence studies of membranes. Journal of Lipid Research, 48(7), 1518-1532. https://doi.org/10.1194/jlr.M600459-JLR200