title: A novel method of determining the number of macromolecules per asymmetric unit from accurate crystal-volume measurements.
abstract: Knowledge of the number of macromolecules per crystallographic asymmetric unit is frequently useful in the determination of crystal structures. A method has been developed to establish this number directly from measurements of the volume and macromolecular contents of a crystal. The volume of a crystal is determined by measuring the volume of solvent that it displaces in a fine capillary tube. The macromolecular mass contained in a crystal is measured by dissolving the crystal in a known amount of water or suitable buffer and then measuring the UV absorbance of the solution. The method has been tested successfully on three different crystals of known structures.
mesh_terms: D000818:Animals; D002645:Chickens; D003460:Crystallization; D018360:Crystallography, X-Ray / Q000379:methods*; D004259:DNA-Directed DNA Polymerase / Q000032:analysis / Q000737:chemistry; D009113:Muramidase / Q000032:analysis; D010446:Peptide Fragments / Q000032:analysis; D011506:Proteins / Q000032:analysis*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D010446:Peptide Fragments; D011506:Proteins; D004259:DNA-Directed DNA Polymerase; D009113:Muramidase