A study of the conformational stability of poly(b-benzyl L-aspartate), poly(g-benzyl L-glutamate) and poly(b-benzyl L-aspartate)/ poly(g-benzyl L-glutamate) blend in the solid state by variable-temperature 13C CP/MAS NMR

13C CP/MAS NMR experiments on polypeptides, poly(b-benzyl L-aspartate) (PBLA), poly(g-benzyl L-glutamate) (PBLG) and PBLA/PBLG blend have been carried out, in order to elucidate the conformational stability of the polypeptides in the solid state over a wide range of temperatures and its blending effect. The PBLA/PBLG blend with a mixture ratio of 1/1 is prepared by adding trifluoroacetic acid (TFA) solution to alkaline water (TFA-alkaline treatment). From these experimental results, it is found that the conformation of PBLA in the PBLA/PBLG blend sample is changed from left-handed helix (aL-helix and/or vL-helix) form to the aR-helix form, and then the origin of the formation of the aR-helix form in PBLA comes from the existence of PBLG. Further, from the variable-temperature 13C CP/MAS NMR experiments results, it is shown that the conformational behavior of PBLA in the PBLA/PBLG blend is similar to that of the TFA-alkaline treated PBLA, and also the conformational behavior of PBLG in the PBLA/PBLG blend is similar to that of the TFA-alkaline treated PBLG. q 2004 Elsevier B.V. All rights reserved.