Site labeling

Zhang, Z.-Y., Dixon, J. E. Active site labeling of the yersinia protein tyrosine phosphatase The determination of the pKa of active site cysteine and the function of the conserved histidine 402. Biochem. 32 (1993) 9340-9345. 

Fig. 5.16. Top STM image of a region of an 02-exposed Si (111 )-7 x 7 surface. The sites labeled with A, B, and C have not been changed by exposure to oxygen. D, E, and F correspond to oxygen-induced dark, bright, and perturbed (gray) sites, respectively. Bottom Tunneling spectra corresponding to the different sites [5.41].

The saturation of linear dienones provides a means of labeling even more remote sites. Labeling of the C-2 and C-3 positions of androstan-7-... 

Figure 4-8. 1NDO/SCI simulation of the wavcfunclion y/(x,xi, = 16, chain I) of the lowest charge transfer-excited stale in a cofacial dimer formed by two five-ring PPV oligomers separated by 4A. Ili/(x,x/, - 16, chain 1) represents the probability amplitude in finding an electron on a given site xt. assuming the hole is centered on site 16 of chain I. The site labeling is the same as that reported on top of Figure 4-7.

Figure 4-2. INDO/SCI-siuiulaled linear absorption spectrum of the eleven-ring PPV oligomer. The vertical lines represent the oscillator strength of the transitions that are described the site labeling used tor the wavcluiiclion analyses is shown on lop.

An important advance on these studies was the possibility of isolating AORs from Fe enriched media with obvious interest for an iron-sulfur center site labeling, with enhanced sensitivity of the Mossbauer studies. The work developed with bacterial systems is advantageous as compared with mammalian systems for isotopic labeling and opens the possibility of a direct measurement of substrate binding. Spectra of the enzyme in oxidized, partially reduced, benzaldehyde-reacted, and fully reduced states were recorded at different temperatures and with variable externally applied magnetic fields (222). In the oxidized enzyme, the clusters are diamag-... 

The question whether PCP and sigma opioids bind to more than one receptor was studied by comparing the binding and regional distribution of binding sites labeled by 3H-PCP, 3H-TCP, 3H-dexoxadrol, ... 

Another method used to study whether these tritiated ligands bind to different groups of binding sites was to determine the regional distribution of binding sites labeled by 3H-TCP and 3H-dexoxadrol. 3H-TCP was used to label PCP receptors because PCP receptors have... 

Automdiograms of binding sites labeled by (A) 3H-TCP and (B) 3H-dexoxadrol in coronal sections of rat brain... 

In the most general case considered here, M is adsorbed on two kinds of sites, labelled V and 2 . Each adsorption process is assumed to be fast enough (when... 

The system is defined as a linear chain of m lattice sites (labelled n = 1, ...,m), which are initially taken as isolated from each other (see Fig. 7.2(a)), so that the GF Gm.m for this state has simple diagonal elements... 

Treatment of 9-(/ -D-ribofuranosyluronic acid)adenine with diphenylphosphoro-chloridate and orthophosphate or tripolyphosphate yields (62) and (63), which, although unstable, inhibit rabbit AMP aminohydrolase and pyruvate kinase, respectively, with behaviour characteristic of active-site-specific reagents.98 Adenylate kinases from several sources are inactivated by iV6-[2- and 4-fluorobenzoyl]-adenosine-5 -triphosphates, with kinetics characteristic of active-site labelling, although these compounds were without effect on yeast hexokinase and rabbit pyruvate kinase.99... 

M. K. Johnson, P. Glynn, Active-Site Labelling and Purification of Neuropathy Target Esterase (NTE) Using a Biotinylated Organophosphorous Compound , Toxicologist 1993, 73,211. 

Figure 4 Triply protonated polypeptide containing one SS linkage with the distances Rj to each positive site labeled by dotted lines (appears in Figure 7 of ref. 3s).

Most exohedral fullerene derivatives of preparative importance are formed by one or several successive 1,2-additions to [6,6]-bonds. For a systematic analysis of the regiochemistry of such reactions it is very useful to introduce a simple site labeling system [3]. The relative positional relationships (such as ortho, meta and para in... 

Figure 1.9 The NMD A receptor, showing the sites of interaction for glutamate (Glu), glycine (Gy), polyamine, Zn2+and Mg2+. Glutamate requires the presence of glycine to open the receptor channel. Polyamine positively modulates, and Zn2+and Mg2+negatively modulate, the opening of the channel. Ketamine and phencyclidine bind to the site labelled PCP.

Fig. 9. Variation of water density around the M3018+ cation. Sites labeled S5 and S4 use the same numbers as used in Figure 8.

Adecreased (22%) number of 5-HT1A receptor binding sites labeled by [3H]8-hydroxy-2(di-n-... 

Oxygen ions occupy the sites labelled 1,2,3,5 and fluorine ions the sites labelled 4,6,7,8,9 on the Aj and A, planes, which indicates clustering of anions. 

We characterized and further studied this basic mechanism of covalent affinity labeling using spectroelectrochemical techniques. The kinetics and stability of quinone oxidation products at high dilution and low pH were consistent with the proposed mechanism, as was the concentration dependence of rapid labeling reactions of the more reactive catechol with the receptor.1215 Spectroelectrochemical and direct cyclic voltametric determination of the half-potentials of the hydroxylated quinones were further consistent with their intermediacy in the labeling reactions of TMC.15 The quinone oxidation products of 4- and 5-HTMC were characterized in part as cyclopentadiene Diels-Alder adducts.15 The instantaneous reactions of these hydroxy TMCs with receptor were consistent with their intermediacy in the TMC reactions. From the concentration dependence of the half-of-sites labeling reactions we could deduce Kd for each isomer fC,(4-HTMC) = 224 98 pM, K/5-HTMC) = 39 17 juM. 

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