A rapid and precise method of measuring Kendrew-model coordinates with theodolites

The Kendrew-model coordinates of KDPG aldolase have been measured with the use of two theodolites which are improved versions of a conventional surveyor's transit. The four angular measurements are converted to Cartesian coordinates and a minimum-error estimate with a minicomputer interfaced to the theodolites. The positions of 1677 atoms of the asymmetric unit of KDPG aldolase were measured by two of the authors in four working days or at the rate of about 60 atoms h^-1. The standard deviations of the bond distances and angles of the model obtained were ± 0.04 Å and about 7°, respectively. The mathematics of the various conversions are presented.