Determination of branching

Similar to the work described by Spohn et al. [34], a trienzyme sensor was developed recently for the determination of branched-chain amino acids (L-valine, L-leucine, and L-isoleucine). Leucine dehydrogenase, NADH oxidase, and peroxidase were coimmobilized covalently on tresylate-hydrophylic vinyl polymer beads and packed into a transparent PILL tube (20 cm X 1.0 id), which was used as flow cell. The sensor was free of interferences from protein and NH4+ and it was stable for 2 weeks. The sensor system was applied to the determination of branched-chain amino acids in plasma with recoveries ranging from 98 to 100% [36],... 

Tong and Tan [18] have performed a simultaneous determination of branched alkylbenzene sulfonates (ABSs) and LASs by HPLC using a C48 column. The elution of ABS produced one large wide peak representing the elution of the compounds with high molecular weight, with the same retention time of the CnLAS. 

A sensitive method for determination of branched-chain L-amino acids is based on labelling individual species with 13 C or 2H, isolating the amino acid by IEC and applying the derivatization scheme depicted in reaction 1. The L-amino acid is converted... 

Nakai, N. Kobayashi, R. Popov, K.M. Harris, R.A. Shimomura, Y. Determination of branched-chain cr-keto acid dehydrogenase activity state and branched-chain cr-keto acid dehydrogenase kinase activity and protein in mammalian tissues. Methods EnzymoL, 324, 48-62 (2000)... 

Establishing the complete structure of oligosaccharides and polysaccharides requires determination of branching positions, the sequence in each branch, the configuration of each monosaccharide unit, and the positions of the glycosidic links—a more complex problem than protein and nucleic acid analysis. 

Girotti S, Roda A, Angelotti M. Bioluminescence flow system determination of branched-chain L-amino acids in serum and urine. Anal Chim Acta 1988 205 229-37. 

Determination of Branches. Reductive dechlorinations were performed with Bu.SnH as reducing agent. We have modifid the original two-step method given by Starnes et. al. (21) to a one-step method (22). To avoid precipitation, a mixture of tetrahydrofuran and xylene is used as solvent. At high conversion, the concentration of xylene and the temperature is increased. By this procedure, a chlorine content less than 0.1% is obtained in 6 h. The experimental details are as previously given.(22). 

A complicated problem is the modeling of branched polymerization. Theoretical aspects of this problem, including the choice of the most suitable mathematical methods and the determination of branching parameters, can be found in the studies of Bamford and Tompa97), Zaidel and Katz98), Zeman and Amundson99, and Graisley et al.100. ... 

This explains why Gossl (31), when comparing results obtained by this method to those obtained by means of the 7.25 p band in CC14 solution, found large errors (up to 50%) with C3 content higher than 10%. The same mistake of using absorptivities of terminal methyls of n-paraffins for the determination of branches is also found in the paper by Bryant and Voter (6). 

Determination of branching ratios for RO2 + NO reactions yields of alkyl... 

Figure 12. Electron ionization mass spectrum of the picolinyl derivative of I4-methyloctadecanoic acid extracted from the gui nea pig Harderian gland, illustrating the determination of branching position. Reproduced from reference [I58J with permission.

The rate coefficient for the overall reaction (R3.1) (= (R3.1a) + (R3.1b)) is ki, which is equal to the sum of the rate coefficients for the two reaction channels, so ki = ki + ib. The branching ratio for the two channels is the ratio of their rate coefficients, so that in the example above the branching ratio is kiJki, while the channel efficiency for channel (R3.1a) is kiJki The determination of branching ratios is as important as the determination of overall rate coefficients but presents greater challenges. 

Before beginning the section on interpretation, mention should be made of the excellent work on determination of branching for polyethylene [ ], crystallinity [ ], theoretical work on structures p, 20, 2ij orientation etc, [ ]. While this work is not covered... 

Beaucage C (2004) Determination of branch fraction and minimum dimension of mass-fractal aggregates. Phys Rev E 70(3) 031401-031411. doi 10.1103/PhysRevE.70.031401... 

Nomenclature for cnd-elhylene copolymers Idem iticat ion of end groups in PMMA at high field Determination of branching in polyethylene. 

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