 Later, with Marilyn Doscher and Flo Quiocho, Richards demonstrated that ribonuclease S as well as carboxypeptidase were enzymatically active in the crystals, important evidence to silence doubts that the conformations of proteins in crystals are directly relevant to their biological activity in cells.Along with colleague Harold W. Wyckoff, who had worked on early research toward the myoglobin structure, the effort to solve the RNase S 3-dimensional structure was spearheaded by Richards.Done in 1966 and published in 1967, the analyses of RNase S  and RNase A jointly made ribonuclease the third distinct protein structure to be determined by X-ray diffraction of crystals, after myoglobin/hemoglobin and hen-egg lysozyme, and the first to be done in the United States.