摘要:
The present invention relates to a group of organic chelators whose affinity for calcium ion in solution is increased by electromagnetic radiation. Specifically, the chelators are related to BAPTA and utilize the addition of an electron-withdrawing group (e.g., diazocarbonyl) to a ring of BAPTA, para to the amino group. Photochemical rearrangement of the diazoacetyl group converts the group to the electron-donating carboxymethyl group, causing the calcium ion efficiency to increase 25 to 50 fold. These chelators when incorporated into rat fibroblasts either by microinjection or by incubation as the membrane-permeable, enzymatically-labile tetraacetoxymethyl ester and flash-photolyzed cause a drop in intracellular free calcine ion to or below resting valves of about 10.sup.-7 M. These chelators are used to generate controlled fast removal of intracellular free calcium ion to mimic or modulate a number of important cellular responses, especially in nerve or muscle.
摘要:
The present invention relates to a group of organic chelators whose affinity for calcium ion in solution is decreased by electromagnetic radiation. Specifically, the chelators are related to fura-2 and utilize the addition of an azide group to the 3-position of the benzofuran ring of a fura-2 type structure. Photolysis of the azide group causes the calcium ion affinity to decrease 100 to 1000 fold. These chelators when incorporated into rat fibroblasts either by microinjection or by incubation as the membrane-permeable, enzymatically-labile esters and flash-photolyzed cause large increases in intracellular free calcium ion. These chelators are used to generate controlled fast elevation of intracellular free calcium ion concentration to mimic or modulate a number of important cellular responses, especially in nerve or muscle.
摘要:
The invention provides labeled proteins suitable for determining the presence of cAMP, other second messengers and organic molecules. The proteins are separately labeled with fluorochromes which, when in close spatial proximity, preferably, less than about 6 nm, interact through the transfer of energy from one fluorochrome to the other.A composition of matter, (S.sub.1.A).sub.n1 (S.sub.2.D).sub.n2 is provided wherein S.sub.1 and S.sub.2 are two proteins which are associated in one state and substantially disassociated in another, the equilibrium between which is controlled by the free concentration of an analyte, and A and D are fluorochromes, the emission wavelength of fluorochrome D overlapping the excitation wavelength of fluorochrome A and the distance between A and D being in sufficiently close proximity to allow the radiationless transfer of energy between the fluorochromes. A and D can be selected from a variety of acceptor, donor pairs such as fluorescein and tetramethylrhodamine and derivatives thereof. The concentration of analytes such as cAMP in a sample can be determined by contacting the sample with (S.sub.1.A).sub.n1 (S.sub.2.D).sub.n2 providing energy near the excitation wavelength of D and measuring the fluorescence of A or D, the concentration of cAMP and other said analytes being determined by the ratio of emission of D to the emission of A, previously calibrated with reference solutions of known analyte concentration.
摘要:
A new class of optical indicators which are capable of memorizing and preserving the spatial localization of intracellular analytes in a time resolved manner is described. The compounds comprise a chromophore carrying a photolabile group capable of undergoing an irreversible and detectable chemical transformation upon irradiation by light. The chromophore is linked to a binding site capable of binding an analyte, wherein binding of the analyte to the binding site alters an optical property of the chromophore, thus altering the ability of the photolabile group to undergo the chemical transformation. Methods and kits for memorizing the spatial localization of the analytes are also described.
摘要:
The present invention relates to a group of organic chelators whose affinity for calcium ion in solution is decreased by electromagnetic radiation. Specifically, the chelators are related to fura-2 and utilize the addition of an azide group to the 3-position of the benzofuron ring of a fura-2 type structure. Photolysis of the azide group causes the calcium ion affinity to decrease 100 to 1000 fold. These chelators when incorporated into rat fibroblasts either by microinjection or by incubation as the membrane-permeable, enzymatically-labile esters and flash-photolyzed cause large increases in intracellular free calcium ion. These chelators are used to generate controlled fast elevation of intracellular free calcium ion concentration to mimic or modulate a number of important cellular responses, especially in nerve or muscle.
摘要:
Described is a method and system for performing path-sensitive value flow analysis on a software program. Concrete state and value alias information is tracked along each statement and each relevant path in an abstract program and is stored as a symbolic state in a symbolic store. The value alias information includes a first set of aliases that identify aliases for a designated value that is being analyzed and a second set of aliases that identify possible aliases for the designated value. The value alias information is obtained using imprecise memory alias analysis. Along each relevant path for each statement, transforms are applied to the sets of aliases to update the first and second sets of aliases. The transforms are applied based on the type of statement being processed. Symbolic states existing at the same location are merged if the value alias information is identical within the symbolic states.
摘要:
A data parallel pipeline may specify multiple parallel data objects that contain multiple elements and multiple parallel operations that operate on the parallel data objects. Based on the data parallel pipeline, a dataflow graph of deferred parallel data objects and deferred parallel operations corresponding to the data parallel pipeline may be generated and one or more graph transformations may be applied to the dataflow graph to generate a revised dataflow graph that includes one or more of the deferred parallel data objects and deferred, combined parallel data operations. The deferred, combined parallel operations may be executed to produce materialized parallel data objects corresponding to the deferred parallel data objects.
摘要:
A data parallel pipeline may specify multiple parallel data objects that contain multiple elements and multiple parallel operations that operate on the parallel data objects. Based on the data parallel pipeline, a dataflow graph of deferred parallel data objects and deferred parallel operations corresponding to the data parallel pipeline may be generated and one or more graph transformations may be applied to the dataflow graph to generate a revised dataflow graph that includes one or more of the deferred parallel data objects and deferred, combined parallel data operations. The deferred, combined parallel operations may be executed to produce materialized parallel data objects corresponding to the deferred parallel data objects.
摘要:
The present invention discloses a new class of calcium chelating compounds which have a decreased 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. However unlike EGTA or BAPTA-like compounds, in which the two halves of the chelator are linked by a simple 1,2-ethanediyl moiety, the compounds of the present invention modify the stereochemical conformation of this linkage by adding bulky substituents or incorporating the linkage into a carbocyclic or heterocyclic ring. 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 precursors of the related 2-nitrosobenzophenones.