Arginine labeling

Fig. 2. NAPI facilitates H2A, H2B release from nucleosomes that are on positively coiled DNA (A) but not negatively coiled DNA (B). The positively coiled DNA (6.0 kb) with a superhelical density of + 0.05 and negatively coiled DNA (6.0 kb) with a superhelical density of -0.05 were reconstituted with lysine, arginine-labeled histones H3, H4, H2A, H2B by NaCl dialysis from 2.0 M to 1.2 M to 0.6 M to 0.1 M NaCl over a 14 h period. The samples were incubated with NAPI at 35 °C for 5 min and applied to a 5-20% sucrose/100 mM NaCl/40 mM Tris, pH 7.8 gradient. After sedimentation at 200,000 X g for 5 h, fractions were collected and the distribution of DNA (bottom panel) was determined on agarose gel and the distribution of protein (top panel) on SDS-PAGE followed by fluorography. These data are unpublished observations (V. Levchenko and V. Jackson). The deg-H2A is degraded H2A in which a 15 amino acid peptide of the C terminal has been proteolytically removed. When H2A, H2B is no longer present in a nucleosome, the C terminal region is sensitive to proteolysis [126] from a protease which is a minor contaminate in the NAPI preparation.

The approach recruited to chemical proteomics in Reference [17] is called SILAC (stable isotope labeling with amino acids in cell culture) and is important in comparative proteomics (Figure 1). SILAC works well with cultured mammalian cells, but prokaryotes defeat it by metabolizing the label (usually supplied in lysine and arginine) into other amino acids. For applications beyond cultured eukaryotic cells, the reductive methylation route to differential labeling [18] is among the alternatives [15]-... 

Figure 5.37 APG can be used to label specifically arginine residues in proteins, producing stable, cyclic Schiff base-like bonds with the side-chain guanidino groups. Photoactivation with UV light then causes ring expansion of the phenyl azide group, initiating covalent bond formation with amines.

For the residue-type assignment of the cross peaks, the SH3 domain was expressed with specifically labeled glycine or arginine residues by using amino acid mixtures where only Gly and Arg were 15N-labeled. Again, yields for the labeled proteins were identical to those of the unlabeled product. Analysis of the corresponding [15N,1H]-HSQC spectra... 

A further study by Olken and collaborators112 describes inactivation of mouse iNOS by /Vc -rncl.hyI-1.-arginine. The inactivation occurs only in the presence of oxygen. Only a small amount of 3H or 14C label from the labeled methyl group of AG-methyl-L-arginine... 

Theoretical calculations predict that, compared to other amino acids, arginine may dimerize and trimeiize in the zwitterionic state. Soft-sampling ESI of the racemate of arginine, with one of the enantiomer isotopically labeled, reveals the formation of stable trimers with NOj" present as counterion. No preference for... 

Figure 1. Elution pattern of toxins from Bio-Rex 70 column in C-labeled arginine feeding. (Fr. fraction number cpm counts per minute and MU mouse units)...

The previously described test system involving in vitro analysis of fat body vitellogenin production and secretion is apparently distinctive in providing evidence for canavanine-mediated curtailment of protein synthesis. At least, canavanine attenuates the amount of [ Hjleucine-labeled protein secreted by the fat body (Fig. 1). As shown in figure 1, the effect of arginine depletion itself is debilitating and it becomes increasingly deleterious with time—quite apart from any effect canavanine may elicit. With increased treatment time, canavanine-... 

NO synthases are oxygenases that carry out a two-step oxidation of L-arginine to L-citrulline with production of NO. In the first step, a normal monooxygenase reaction, i -N -hydroxyarginine is formed (Eq. 18-65, step a). In the second step (Eq. 18-65, step b) NO is formed in a three-electron oxidation. In this equation the symbols and + indicate positions of incorporation of labeled 02 atoms in the intermediate and final products. 

Figure 23-45 (A) Some aspects of the structure of bacteriorhodopsin. Ribbon diagram with the retinal Schiff base in ball-and-stick representation. At the top the helices are labeled as in Fig. 23-41. The locations of aspartate, glutamate, and arginine residues that might carry protons during the proton pumping action are indicated. Retinal is shown attached to lysine 216.

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