The present invention provides a fast and efficient method for determining the three-dimensional conformation of a protein. The steps of the method of the invention include: 1) formation of physical distance constraints, e.g., forming intramolecular chemical crosslinks of known size between residues of a protein; 2) enriching the number of the molecules that have intramolecular chemical crosslinks in the reaction pool, e.g., using size separation to remove proteins with intermolecular bonds; 3) exposing the enriched reaction pool to a protease that cuts the protein at specific sites to produce peptide fragments; 4) measuring the size of the peptide fragments to determine linkage sites with a certain spatial relationship in the protein; and 5)interpreting the data produced to determine spatial geometry and protein structure based on the deduced spatial relationship of the linkage sites. The information is preferably analyzed with aid from a computer system, which can be used to generate and/or analyze distance constraints between amino acids.