AbstractThe small‐angle X‐ray scattering ofL‐leucine dehydrogenase (EC 1.4.1.9) fromBacillus sphaericusin 0,2 M sodium phosphate buffer (pH 7,28) was investigated. The following molecular parameters were determined: radius of gyration, as 50,8 Å from the Guinier plot and 48,5 Å from the distance distribution function; molecular weight, as 267 000; volume, as 623 000 Å3; and degree of hydration, as 0,95 g H2O/g of enzyme. By comparing the observed scattering curve with those calculated with a number of models, a hollow cylinder with 47,0 Å of outer radius, 10,3 Å of inner radius and 119,0 Å of length was proposed as a most plausible model for