Ramachandran method

One method of overcoming some of the instability and loss in strength of oxychloride cements when exposed to water has been to modify them by impregnation with sulphur (Beaudoin, Ramachandran Feldman, 1977). The resulting material appears to be a composite in which the respective components complement each other. The magnesium oxychloride part has relatively poor resistance to water as initially formed, whereas the sulphur is difficult to wet and is completely insoluble in water. 

The effect of micelles on these spontaneous hydrolyses is difficult to explain in terms of kinetic solvent effects on these reactions. Mukerjee and his coworkers have refined earlier methods for estimating apparent dielectric constants or effective polarities at micellar surfaces. For cationic and zwitterionic betaine sulfonate micelles Def is lower by ca 15 from the value in anionic dodecyl sulfate micelles (Ramachandran et al., 1982). We do not know whether there is a direct connection between these differences in effective dielectric constant and the relation between reaction rates and micellar charge, but the possibility is intriguing. 

Ramachandran, G. and Srinivasan, R. Fourier Methods in Crystallography. Wiley-Interscience, New York, 1970. 

Finally, the structure of the thermodynamically favored isomer of [l2(OCH3)2Ti2]2- was deduced from conformational analysis of X-ray structural data of some of the complexes using Ramachandrarfs method. The dihedral angles and T of the amino acid residues observed in the X-ray structures were determined and were correlated in a Ramachandran diagram. 

A30/Ai = 0, k /k2 = 1. This problem was first analyzed numerically by Brian and Beaverstock (12). Approximate analytical solution to this problem is also available (Ramachandran (13)). Figure 3 has been mainly presented to test the method for multi-step reaction scheme and hence detailed comparison of the accuracy of the solution and the influence of the number of collocation points was not done for this case. 

The average of these converged structures is taken as the protein structure, whose precision can be assessed by the deviations of the individual structures from the average. The quality of the final structure can be described in terms of this root mean square deviation, for both the peptide backbone and side chains, and to some extent by the extent to which it conforms to limitations of dihedral bond angles and interatomic contacts anticipated from thousands of previously known structures (the Ramachandran plot ). By all criteria, NMR structures of proteins that are determined in this way are comparable to structures determined by x-ray crystallography. In addition, NMR methods can be applied to evaluate the... 

Allen, J.M., Balcavage, W.X., Ramachandran, B.R., Shrout, A.L. (1998) Determination of Henry s law constants by equilibrium partitioning in a closed system using a new in situ optical absorbance method. Environ. Toxicol. Chem. 17, 1216-1221. 

Ramachandran LK, Witkop B. V-bromosuccinimide cleavage of peptides. Methods Enzymol. 1967 11 283-299. 

This value was obtained by Ramachandran (1961) by the Goodwin and Morton (1946) method. So far there is no proof that the indole component of thiostreptin is identical with tryptophan or with the recently discovered derivative of 8-hydroxy-quinoline (Drey et ah, 1961). 

Chart I (Ramachandran and Witkop, 1959) summarizes these results The two sequences Try-Ala (17-18) and Try-Lys (52-53) are exposed and fully reactive NBS the sequence Try-Thr (151-152) is buried (cf. Herskovits and Laskowski, 1960) in the A-protein, but becomes accessible to NBS in the tryptic hexadecapeptide. In addition to the methods of spectral perturbation of chromophoric groups by polyhydroxy compounds, spectrophotometric titration studies, and ultraviolet difference spectra the reactivity of tryptophan toward selective agents such as NBS may offer a new tool for assessing influences of secondary or tertiary structure in this area. 

Ramachandran recently extended this work and determined the tryptophan content and tryptophyl sequences of proteins from six different plant viruses by the NBS titration as well as other methods (Table XX) (Ramachandran, 1960). 

Bascle, J., Garel, T., Orland, H. and Velikson, B. (1993). Biasing a Monte Carlo chain growth method with Ramachandran s plot application to twenty-L-alanine. Biopolymers, 33, 1843-1849. 

Discussions on flow modeling so far have been more or less restricted to singlephase reactors. However, in a broad range of application areas, multiple phases are involved in chemical reactions (see examples cited by Ramachandran and Choudhari, 1983 Doraiswamy and Sharma, 1984 Kunii and Levenspiel, 1991 Shah, 1991 Dudukovic et al, 1999). Reactors carrying out such reactions are generically termed multiphase reactors. There are several types of multiphase reactors and several methods are available to classify these reactors. One of the simplest methods of... 

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