Trinitrophenyl-ATP

Ap4A, diadenosine tetraphosphate BBG, Brilliant blue green BzATP, 2 - 3 -0-(4-benzoyl-benzoyl)-ATP cAMP, cyclic AMP CCPA, chlorocyclopentyl adenosine CPA, cyclopentyl adenosine CTP, cytosine triphosphate DPCPX, 8-cyclopentyl-1,3-dipnopylxanthine IP3, inosine triphosphate lpsl, diinosine penta phosphate a,p-meATP, a,p-methylene ATP p.y-meATP, p.y-meihylene ATP 2-MeSADP, 2-methylthio ADP 2-MeSAMP, 2-methylthio AMP 2-MeSATP, 2-methylthio ATP NECA, 5 -W-ethylcarboxamido adenosine PPADS, pyridoxal-phosphate-6-azophenyl-2, 4 -disulfonic acid PLC, phospholipase C RB2, reactive blue 2 TNP-ATP, 2, 3 -0-(2,4,6-trinitrophenyl) ATP. 

Figure 1 Molecular structures of the chromophores involved in the current work (A) crystal violet (CV), (B) malachite green (MG), (C) rhodamine B (rhB), and (D) 2,-(or-3 )-0-(2, 4, 6-trinitrophenyl) adenosine S -triphosphatc (TNP-ATP).

Figure 6. Time course of change in catalytic specificity (upper panel) and Ca2+ dissociation from extracytoplasmic low affinity sites (lower panel) following phosphorylation of the SR Ca2+-ATPase with ATP. The amount of ADP-insensitive phosphoen-zyme (E2P) was measured in two ways (I) [y-32P]ATP was included in the reaction mixture and the radioactivity incorporated into the enzyme was determined after acid quenching at various time intervals. To remove the ADP-sensitive phosphoenzyme so that only ADP-insensitive phosphoenzyme was measured, ADP was added 4 sec before the quench (upper panel, right scale) (2) by the enhancement of fluorescence from a trinitrophenyl-derivative of ADP bound in the catalytic site in exchange with ADP after the phosphorylation (upper panel, left scale). The change in Ca2+ binding was measured indirectly by use of murexide as an indicator of free Ca2+ in the medium. The data show that Ca2+ dissociates simultaneously with formation of E2P. The data points were taken from Andersen et al., 1985.

Trinitrophenyl-nucleotides constitute a unique class of fluorescent ATP-ana-logs, since they bind at the catalytic site of the phosphoenzy me of the Ca2+-ATPase after departure of ADP and give off a tremendous fluorescence signal upon conversion of the phosphoenzyme intermediate from ADP-sensitive to ADP-insen-sitive (c.f., Figure 6), possibly reflecting a hydrophilic-hydrophobic transition related to closure of the catalytic site (Andersen et al., 1985 Seebregts and McIntosh, 1989). 

When ATP and 2,4,6-trinitrobenzenesulphonic acid are mixed at pH 9.5, 2 - (or 3 -) 0-(2,4,6-trinitrophenyl)adenosine-5 -triphosphate (22) is formed, which binds to, and is hydrolysed by, heavy meromyosin. This ATP derivative exhibits reversible formation of a Meisenheimer complex, with pK 5.1. The... 

TNP-ATP 2 (3 )-o-(2,4,6-trinitrophenyl)adenosine 5 -triphosphate Tris tris(hydroxymethyl)aminomethane... 

Figure 28.1 shows data for the binding of a ligand (TNP-ATP, trinitrophenyl adenosine triphosphate) to DnaB helicase protein, a hexamer of six identical subunits. This protein is involved in the replication of DNA. The figure shows... 

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