1. The molecular weight and molecular shape of Taka-amylase A were studied by the measurements of sedimentation constant, diffusion coefficient and viscosity.
2. If we assume the molecule of a prolate ellipsoid of revolution of axial ratio 4.00 without or with scarce hydration, the molecular weight would be 51, 000, which is in good agreement with previous data. The length of the major axis of the molecule is 125 Å and that of the minor axis 30 Å, respectively.
3. The partial specific volume of Taka-amylase A is 0.700 and less than the calculated value from the specific volumes of constitutional amino acids.
In conclusion, the authors express their hearty thanks to Prof. S. Akabori and Mr. T. Ikenaka, of the Faculty of Science, Osaka University who supplied us the valuable sample of Taka-amylase and the authors are also indebted Prof. K. Fukai of the Institute for Microbiological Desease, Osaka University for his kind guidance for taking the photographs of sedimentation diagram.