Chemicals labelling

Examples of typical packaging labels from reagent grade chemicals. Label (a) provides the actual lot assay for the reagent as determined by the manufacturer. Note that potassium has been flagged with an asterisk ( ) because its assay exceeds the maximum limit established by the American Chemical Society (ACS). Label (b) does not provide assayed values, but indicates that the reagent meets the specifications of the ACS for the listed impurities. An assay for the reagent also is provided. 

Xandiene dyes have not exhibited health or safety properties warranting special precautions however, standard chemical labeling instmctions are required. Toxicological properties of important dyes are Hsted in Table 2 (12). 

Procedures for shipping boric acid esters depend on the particular compound. Aryl borates produce phenols when in contact with water and are therefore subject to shipping regulations governing such materials and must carry a Corrosive Chemical label. Lower alkyl borates are flammable, flash points of methyl, ethyl, and butyl borates are 0, 32, and 94°C, respectively, and must be stored in approved areas. Other compounds are not hazardous, and may be shipped or stored in any convenient manner. Because borate esters are susceptible to hydrolysis, the more sensitive compounds should be stored and transferred in an inert atmosphere, such as nitrogen. 

Studies of other members of the family have also added support to the topological model shown in the Fig. 3. In particular, chemical labelling of the native and mutated tetracycline transporter has confirmed the cytoplasmic location of the N-terminus and the loop connecting transmembrane helices 2 and 3 [231,232]. Protease digestion experiments on this protein have also provided preliminary evidence for the cyto-... 

Marks KM, Nolan GP (2006) Chemical labeling strategies for cell biology. Nat Methods 3 591-596... 

Soh, N. (2008). Selective chemical labeling of proteins with small fluorescent molecules based on metal-chelation methodology. Sensors 8, 1004-24. 

Some form of chemical labeling process must be used regardless of whether the final oligo conjugate is created by enzymatic or strictly chemical means. If enzymatic modification is to be done, the initial label still must be incorporated into an individual nucleoside triphosphate, which then is polymerized into an existing oligonucleotide strand (Section 1, this chapter). Fortunately, many useful modified nucleoside triphosphates are now available from commercial sources, often eliminating the need for custom derivatization of individual nucleotides. 

Forster, A.C., Mclnnes, J.L., Skingle, D.C., and Symons, R.H. (1985) Non-radioactive hybridization probes prepared by the chemical labeling of DNA and RNA with a novel reagent, photobiotin. Nucleic Acid Res. 13, 745-761. 

Maisch D, Wadhwani P, Afonin S, Bottcher C, Koksch B, Ulrich AS (2009) Chemical labeling strategy with (R)- and (S)-trifluoromethylalanine for solid state 19F NMR analysis of peptaibols in membranes. J Am Chem Soc 131 15596-15597... 

Detritiation of cooling water in nuclear power plants. Biosynthesis of chemicals labelled with D or T. 

The isotope-coded affinity tag approach utilizes chemical labeling that allows quantitation when combined with mass spectrometry. ICAT is desirable because the chemical labeling takes advantage of the mass defects of monoisotopic stable isotopes. ICAT uses an ICAT reagent to differentially label protein samples on their cysteine residues. ICAT is advantageous because it permits the evaluation of low-abundance proteins and proteins at both extremes of molecular weights and isoelectric points.60... 

Chen, J. G., Liu-Chen, S., and Rudnick, G. (1998) Determination of external loop topology in the serotonin transporter by site-directed chemical labeling [In Process Citation], J. Biol. Chem. 273,12675-12681. 

The idea behind the use of chemical labeling is a straightforward approach to simplify peak assignment into the proper ion series. If either peptide s C- or N-terminus is labeled by specific isotopic cluster, the labeled ions are easily recognizable on the spectrum and determination of the sequence string is no longer a problem. 

Can chemicals labeled as technical grade be used as standards in analytical procedures Explain. 

Methods used to demonstrate the existence of membrane phospholipid asymmetry, such as chemical labelling and susceptibility to hydrolysis or modification by phospholipases and other enzymes, are rmsuitable for dynamic studies because the rates of chemical and biochemical reactions are of a different order compared to the transmembrane translocahon of the phospholipids. Indirect methods have therefore been developed to measure the translocation rate which are consequent on the loss of membrane phospholipid asymmetry. Thus time scales appropriate to rates of lipid scrambling under resting conditions or when the forces preserving the asymmetric phospholipid distribution are disturbed can be monitored. Generally the methods rely on detecting the appearance of phosphatidylserine on the surface of cells. Methods of demonstrating Upid translocation in mammalian cells has been the subject of a recent review (Bevers etal., 1999). 

The phenylselenocysteine has also been used successfully to chemically append analogues of methyl- or acetyl-lysine, important histone modifications that can contribute to chromatin structure and accessibility of transcriptional machinery in eukaryotes. By introducing phenylselenocysteine into the Xenopus histone H3, both acetyl-lysine and mono-, di-, and trimethyl-lysine analogues were appended to the purified unnatural amino acid-containing FI 3 protein (Figure 10). " Additionally, the H3 protein with a modification mimicking acetylation of lysine 9 can be deactylated by a histone deacetylation complex and is also a substrate for phosphorylation by Aurora B kinase. Such purified and chemically labeled histones are likely functional in nucleosomes, and preparation of specifically modified histones for comprehensive analysis of chromatin structure and accessibility is particularly suited to this chemical labeling technique. 

Another consideration when choosing a detector is whether it is important to preserve the separated analytes, either for use or for further analysis. Some methods, such as evaporative laser scattering detection and mass spectrometry, destroy the sample during the measurement. Other methods, such as fluorescence or radiochemical detection, may require chemical labeling of the analytes ... 

To avoid too fast an energy transfer and enhance the selectivity of the laser excitation of the chosen sites in large biomolecules, it seems very promising to use their chemical labeling. This is especially important in the mapping of the sequences of DNA nucleotide bases having very close spectral properties. The first experiments on the MPI of dye-labeled nucleic acid bases were quite a success [11]. 

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