T-Alanine Ala

The obtained L-a-alanine grafted polymer 49 was further reacted with p-nitrophenyl ester-containing bases, according to the procedure mentioned earlier. From the NMR and UV spectra, the polymers obtained were found to contain about 98% adenine units 50 (A-Ala-PEI) and about 100% thymine units for polymer 51 (T-Ala-PEI). 

Table 1. Initial rate values for N-Br alanine decomposition at different N-Br-alanine concentrations. [Ala] = 0.02M, [NaOH] = 0.23M, T = 298 K.

Fig. 3. Logarithmic plot showing compliance with first order rate law respect to N-Br-alanine concentration for the N-Br-alanine decomposition reaction. [Ala] = 0.02 M, [NaOH] = 0.23M, T = 298 K. 

Nagasawa T, H Ohkishi, B Kawakami, H Yamano, H Hosono, Y Tani, H Yamada (1982) 3-chloro-D-ala-nine chloride-lyase (deaminating) of Pseudomonas putida CR 1-1. Purification and characterization of a novel enzyme occurring in 3-chloro-D-alanine-resistant pseudomonads. J Biol Chem 257 13749-13756. 

Table 4. Isotropic 15N shielding (asymmetry parameter (t/) of solid polypeptides [Ala, X] containing 15N-labelled L-alanine residue in the a-helix, aL-helix, and /3-sheet forms. 

The percent conversion of the monomer to the polypeptide can be estimated by the quantity 100 (Aq - At) / Aq, where Aq and At are the integrated intensities of the ester band at the start and time t, respectively. At 40 °C, it tended to saturate at about 30 % for the Y-type films of L-NaphAla-C-i s, and L-PyrAla-G 8, although the conversion for the LB film of long-chain ester of alanine (L-Ala- Ci s) reached to 90 % [52]. This difference is considered to be due to a larger steric hindrance of the aromatic rings. 

From the H CRAMPS NMR spectra, therefore, it was possible to determine the NH proton chemical shift value for [Ala ]n-2 (a-helix 6 = 8.0) which is identical with that determined using BR-24 (2.0 kHz). Further, it was possible to determine the " NH proton chemical shift for [Ala ]n-1 (/3-sheet, 6 = 8.6) using the MREV-8 pulse sequence at 3.5 kHz. However, unfortunately, the NH proton chemical shift values for [Ala]n-2 and [Ala]n-t could not be determined because the line shapes of the " NH signals exhibit an asymmetric doublet pattern in this system also. Thus, it is found that determination of the true NH chemical shift of poly(L-alanines) can be achieved to measure fully N-labelled samples at higher MAS speed (3.5 kHz) and that these chemical shifts depend on conformation (a-helix 6 = 8.0 /3-sheet S = 8.6). This is the first determination of the true NH proton chemical shifts of poly(L-alanines) by H CRAMPS NMR. 

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