Diazofluorene — A new reagent for fluorescent photochemical labelling of membrane hydrophobic core

Anjaneyulu, P. S. R.; Lala, Anil K.

doi:10.1016/0014-5793(82)80727-8

Cited by 10 publications

(2 citation statements)

References 12 publications

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“…Our interest in fluorenyl fatty acids stems from the fact that we have recently reported diazofluorene (DAF) as a new photoactivatable reagent for labeling membrane hydrophobic core in both artificial (Anjaneyulu & Lala, 1982;Anjaneyulu et al, 1984) and natural (Pradhan & Lala, 1987) membranes. These studies indicated that DAF effectively labels membrane-spanning domains of integral membrane proteins in human erythrocytes (Pradhan & Lala, 1987).…”

Section: Discussionmentioning

confidence: 99%

Design, synthesis, and fluorescence studies of fluorenyl fatty acids as new depth-dependent fluorescent probes for membranes: getting over the looping-back problem

Lala

Dixit²,

Koppaka³

et al. 1988

Biochemistry

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Fluorescent fatty acids have proved very useful in studying the membrane hydrophobic core. They readily partition into membranes or can be converted to phospholipids, which form integral components of membranes. By attaching the fluorescent chromophore to different positions along the alkyl chain of fatty acids, e.g., an anthroyloxy group attached via an ester linkage to n-hydroxystearic acid, membranes have been probed at different depths. While this is an interesting approach and has been extensively used, relatively little attention has been paid to the molecular design of these probes in order to have minimal membrane perturbation. In the present study we have looked into the general problem of design of such depth-dependent membrane probes. We report here a series of fluorenyl fatty acids with varying fatty acid chain lengths, Le., (2-fluoreny1)acetic acid, -butyric acid, -hexanoic acid, and -octanoic acid, in order to obtain information at different depths in the membrane hydrophobic core. To see the effect of attachment of a hydrophobic tail on the orientation of such fatty acids in membranes, an n-butyl group was linked to the C-7 position of fluorene in (2-fluoreny1)butyric acid to get 4-(7-n-butylfluoren-2-yl)butyric acid. Further, to assess their ability to act as depth-dependent fluorescent probes, these fatty acids were incorporated in vesicles prepared from egg phosphatidylcholine, and their fluorescence quenching was studied with potassium iodide, Cu(II), 9,lO-dibromostearic acid, and 12-bromostearic acid. The Stern-Volmer plots so obtained clearly indicated the following depth order: 8-(2-fluorenyl)octanoic acid > 6-(2-fluorenyl)hexanoic acid > 4-(7-n-butylfluoren-2-yl)butyric acid > 4-(2-fluorenyl)butyric acid > (2-fluoreny1)acetic acid. These results indicate that the fluorenyl fatty acids reported here do probe the membrane at different depths, depending on their transverse location. In addition, the attachment of a hydrophobic tail helps in better aligning the probe in membranes and could thus overcome the problems associated with looping back of such fatty acids to the membrane-water interface. These results were also supported by fluorescence polarization data. The general design strategy utilized here can in principle be extended to other membrane probes like photoactivatable fatty acids.

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Section: Discussionmentioning

confidence: 99%

Design, synthesis, and fluorescence studies of fluorenyl fatty acids as new depth-dependent fluorescent probes for membranes: getting over the looping-back problem

Lala

Dixit²,

Koppaka³

et al. 1988

Biochemistry

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“…Lala was quick to recognize the opportunity to develop highly reactive carbenes, capable of rapid insertion into neighboring chemical bonds upon generation by photolysis. His work on diazafluorene as a “new fluorescent photochemical reagent” provided an alternative to light activatable radio‐labels (Anjaneyulu and Lala 1982). Over the last 20 years, Lala and an extraordinarily dedicated band of graduate students developed photolabeling into an important and powerful tool for analyzing the organization of proteins in membranes using the human erythrocyte glucose transporter, Staphylococcus aureus α‐toxin and diphtheria toxin as examples, where the utility of this method was clearly demonstrated (Lala et al 1990; D'Silva and Lala 1998 D'Silva and Lala 2000).…”

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confidence: 99%

Anil Lala (1950–2004)

Balaram

2004

Protein Science

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The Reaction of Diazocyclopentadienyl Compounds with Cyclomanganated Arenes as a Route to Ligand‐Appended Cymantrenes

et al. 2004

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The thermolysis of various cyclomanganated arenes in the presence of 5‐diazocyclopentadiene, 7‐diazoindene or 9‐diazofluorene afforded the corresponding arenes tethered with cymantrenyl, benzocymantrenyl or dibenzocymantrenyl groups in fair to good yields. This reaction implies a multi‐facetted mechanism that consists of three steps: the insertion of an alkylidene moiety into a C−Mn bond, a CAr−C bond formation and several haptotropic ring‐slippages. The coupling reaction has proven to be particularly efficient with Mn(CO)4 chelates derived from acetylarenes and nitrogen‐containing heterocycles. In one case of a 2‐phenyl‐2‐oxazoline complex, the coupling with 9‐diazofluorene yields a new η1‐dibenzocymantrene complex in which the Mn(CO)4 moiety is chelated and is part of a six‐membered metallacycle. The results of this study are mainly supported by the molecular structures of nine new complexes obtained by X‐ray diffraction analyses. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

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Diazofluorene — A new reagent for fluorescent photochemical labelling of membrane hydrophobic core

Cited by 10 publications

References 12 publications

Design, synthesis, and fluorescence studies of fluorenyl fatty acids as new depth-dependent fluorescent probes for membranes: getting over the looping-back problem

Design, synthesis, and fluorescence studies of fluorenyl fatty acids as new depth-dependent fluorescent probes for membranes: getting over the looping-back problem

Anil Lala (1950–2004)

The Reaction of Diazocyclopentadienyl Compounds with Cyclomanganated Arenes as a Route to Ligand‐Appended Cymantrenes

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