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Electron microscopic observations on the super helical structure of synthetic polypeptide

✍ Scribed by Saburo Ishikawa; Toshio Kurita

Publisher
Wiley (John Wiley & Sons)
Year
1964
Tongue
English
Weight
760 KB
Volume
2
Category
Article
ISSN
0006-3525

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✦ Synopsis

A study of the super helical structure of synthetic polypeptideb, such aa poly-7benzyl-r, (or L)-glutamate (PBDG or PBLG) waa carried out. The PBG waa dissolved in dimethylformamide (DMF). The solution waa either allowed to remain at room temperature for a long time or poured into some fatty acid, such aa formic acid, acetic acid, propionic acid, or caprylic acid. Whether the polymer precipitated slowly or rapidly depended upon the aging of the solution or the nature of the acid used. The precipitated gels revealed the coiled coil fibrils, but the featureand degree of coiling varied, depending upon the length of aging or the nature of the acid used for precipitation. After a short aging of the solution, there was no helical structure in the gels. After long aging, very fine-coiled coil macrofibrils or small spindle-like fibrils were obtained. The macrofibrils consisted of the spindle-like fibrils which in turn consisted of microfibrils (diam. 60-7OA.). When using the fatty acid precipitation very fine to medium fine super helices were obtained. Extremely fine super helices were obtained in propionic acid.

When P M L G DCA solution waa stored for a long time, another type of precipitation waa obtained, one giving evidence of so-called cross-j3 crystallization and no coiled coil fibrils. The precipitation of cross-p fibrils waa obtained when the concentration of the solution was above 8%.

In these gels the PBG chains have an a-helical conformation.

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