摘要:
A scanning confocal microscope scans a sample with an incident beam of radiation, in a raster scan pattern, causing the sample to fluoresce and emit visible radiation in at least two wavelengths. A portion of the fluorescent light retraces a portion of the path optical of incident beam, to a dichroic mirror that separates it from the incident beam for detection by a pair of photomultiplier tubes. A data processor accumulates digital data from the photomultiplier tubes to form a succession of image data frames of the sample being scanned, in the two wavelengths. Image data for a selected number of frames in each wavelength is averaged and then recorded on a single track of a recording system, in an alternating fashion with averaged data for the other wavelength. In addition, a ratio of the averaged data for the two wavelengths is delivered to a video display.
摘要:
The invention discloses fluorescent chelator compounds that are especially useful to monitor and measure cytosolic concentrations of alkali metal cations such as Na.sup.+, K.sup.+, and Li.sup.+. The new compounds are comprised of: (1) crown ethers (that may or may not have substituent groups attached to the core carbons, but will always contain at least one core nitrogen) that are linked via the core nitrogen(s) to at least one (2) fluorophore that contains an additional heteroaromatic liganding center. In the currently preferred dye, SBFI, the core compound is crown ether 1,7-diaza-4,10,13-trioxacyclopentadecane and the heteroaromatic fluorophores are benzofurans that are linked to isophthalate groups. Selectivities for Na.sup.+ over K.sup.+ of about 20 are observed, resulting in effective dissociation constants for Na.sup.+ of about 20 mM against a background of 120 mM K.sup.+. Increasing [Na.sup.+ ] increases the ratio of excitation efficiency at 330-345 nm to that at 370-390 nm with emission collected at 450-550 nm, so that ratio fluorometry and imaging work at the same wavelengths as used with the well-known Ca.sup.2+ indicator fura-2. If the macrocyclic ring is increased in size to a 1,10-diaza-4,7,13,16-tetraoxacyclooctadecane, the chelators become selective for K.sup.+ over Na.sup.+. If the ring is decreased in size, for example to a 1,7-diaza-4,10-dioxacyclododecane, the chelators become selective for Li.sup.+ over Na.sup.+.
摘要:
The present invention discloses a group of calcium chelating compounds which have a descreased affinity for calcium following illumination. These new compounds contain a photolabile nitrobenzyl derivative coupled to a tetracarboxylate Ca.sup.2+ chelating parent compound having the octacoordinate chelating groups characteristic of EGTA or BAPTA. In a first form, the new compounds are comprised of a BAPTA-like chelator coupled to a single 2-nitrobenzyl derivative, which in turn is a photochemical precursor of a 2-nitrosobenzophenone. In a second form, the new compounds are comprised of a BAPTA-like chelator coupled to two 2-nitrobenzyl derivatives, themselves photochemical prcursors of the related 2-nitrosobenzophenones.The present invention also discloses a novel method for preparing 1-hydroxy- or 1-alkoxy-1-(2-nitroaryl)-1-aryl methanes. Methanes of this type are critical to the preparation of, or actually constitute, the photolabile Ca.sup.2+ chelating compounds disclosed and claimed herein.
摘要:
This invention provides tandem fluorescent protein construct including a donor fluorescent protein moiety, an acceptor fluorescent protein moiety and a linker moiety that couples the donor and acceptor moieties. The donor and acceptor moieties exhibit fluorescence resonance energy transfer which is eliminated upon cleavage. The constructs are useful in enzymatic assays.
摘要:
A generic structure for the peptides of the present invention includes A-X-B-C, where C is a cargo moiety, the B portion includes basic amino acids, X is a cleavable linker sequence, and the A portion includes acidic amino acids. The intact structure is not significantly taken up by cells; however, upon extracellular cleavage of X, the B-C portion is taken up, delivering the cargo to targeted cells. Cargo may be, for example, a contrast agent for diagnostic imaging, a chemotherapeutic drug, or a radiation-sensitizer for therapy. Cleavage of X allows separation of A from B, unmasking the normal ability of the basic amino acids in B to drag cargo C into cells near the cleavage event. X is cleaved extracellularly, preferably under physiological conditions. D-amino acids are preferred for the A and B portions, to minimize immunogenicity and nonspecific cleavage by background peptidases or proteases.
摘要:
The present invention provides miniSOG proteins, polynucleotides, and methods of use. When expressed in a bacterial or mammalian cell, miniSOG proteins spontaneously incorporate flavin mononucleotide and produce fluorescence and singlet oxygen upon excitation. Uses include optical and electron microscope imaging, in vivo imaging, detection and localization of protein-protein interactions, and photoablation.
摘要:
Substrates for β-lactamase of the general formula I in which one of X and Y is a fluorescent donor moiety and the other is a quencher (which may or may not re-emit); R′ is selected from the group consisting of H, lower (i.e., alkyl of 1 to about 5 carbon atoms) and (CH2)nOH, in which n is 0 or an integer from 1 to 5; R″ is selected from the group consisting of H, physiologically acceptable metal and ammonium cations, —CHR2OCO(CH2)nCH3, —CHR2OCOC (CH3)3, acylthiomethyl, acyloxy-alpha-benzyl, delta-butyrolactonyl, methoxycarbonyloxymethyl, phenyl, methylsulphinylmethyl, beta-morpholinoethyl, dialkylaminoethyl, acyloxyalkyl, dialkylaminocarbonyloxymethyl and aliphatic, in which R2 is selected from the group consisting of H and lower alkyl; A is selected from the group consisting of S, O, SO, SO2 and CH2; and Z′ and Z″ are linkers for the fluorescent donor and quencher moieties. Methods of assaying β-lactamase activity and monitoring expression in systems using β-lactamase as a reporter gene also are disclosed.
摘要:
Fluorescent indicators including a binding protein moiety, a donor fluorescent protein moiety, and an acceptor fluorescent protein moiety are described. The binding protein moiety has an analyte-binding region which binds an analyte and causes the indicator to change conformation upon exposure to the analyte. The donor moiety and the acceptor moiety change position relative to each other when the analyte binds to the analyte-binding region. The donor moiety and the acceptor moiety exhibit fluorescence resonance energy transfer when the donor moiety is excited and the distance between the donor moiety and the acceptor moiety is small. The indicators can be used to measure analyte concentrations in samples, such as calcium ion concentrations in cells.
摘要:
The present invention relates generally to fluorescent proteins and fluorescent protein variants, and more specifically to monomeric and dimeric forms of Anthozoan fluorescent proteins. In one aspect, the present invention provides variants of fluorescent proteins, where the variants have a reduced propensity to tetramerize, and form dimeric or monomeric structures. In a further aspect, the present invention provides variants of fluorescent proteins, the variants being characterized by more efficient maturation than corresponding fluorescent proteins from which they are derived. The invention also relates to methods of making and using such fluorescent proteins and fluorescent protein variants, including fluorescent protein monomers and dimers.
摘要:
The disclosure provides method and compositions for visualizing protein turnover. In particular, the disclosure provides methods and compositions useful for measuring the age of particular proteins or the dynamics of localized protein translation.