Biochemical and crystallographic data for phaseolin, the storage protein from Phaseolus vulgaris

Abstract

We have isolated and biochemically characterized a major seed protein from Phaseolus vulgaris (common garden green bean) that appears to be identical with a form of the storage protein of that plant seed known as phaseolin. We have further shown that it appears very similar in most properties to the storage protein from Canavalia ensiformis (jack bean) which we have solved to 3.0-A resolution using X-ray diffraction techniques. [McPherson, A., & Rich, A. (1973) J. Biochem. (Tokyo) 74, 155-160; McPherson, A., & Spencer, R. (1975) Arch. Biochem. Biophys. 169, 650-661; McPherson, A. (1980) J. Biol. Chem. 255, 10472-10480]. We have crystallized phaseolin and conducted a preliminary X-ray diffraction analysis on it as well. The data show the crystals to be of pseudo cubic space group P432, although the symmetry can be, strictly speaking, only P1. The unit cell has one trimeric molecule of 150 000 daltons in a unit cell of dimensions a = b = c = 66.6 and alpha = beta = gamma = 90 degrees. The crystals apparently possess some form of disorder that makes reconciliation of the unit cell contents with the observed crystallographic properties difficult, although they do diffract strongly to better than 2.8-A resolution. No evidence of twinning has been observed.