Studies on Peanut Proteins

Part III. MolecuIar dimension and subunit structure of arachin

Abstract

Arachin was purified by gel filtration chromatography on a Sephadex G-200 column and by ion exchange chromatography on a DEAE-Sephadex A-50 column in 0.076M tris-citrate buffer with 0.01M 2-mercaptoethanol (pH 8.6). The molecular dimension and the subunit structure were investigated.
The axial ratio of the monomer form (9.2S, M.W. 180, 000 by sedimentation-diffusion method) was estimated to be 3.5 from the frictional ratio f/f0=1.288 and 4.6 from the intrinsic viscosity [η]=0.060dl/g assuming the molecule of a prolate ellipsoid of revolution with 30% hydration, and of the dimer form (14.7S, 350, 000) 3.0 from f/f_J=1.252 and 3.2 from [η]=0.044 dl/g.
It was considered from the results of ultracentrifuge, gel electrophoresis and N-terminal amino acid analysis that arachin was consisted of six kinds of main subunits having the average molecular weight of 29, 000, which possessed three glycines, two (iso-) leucines, and one valine as the N-terminal amino acid.