Solution of the structure of Aspergillus niger acid α-amylase by combined molecular replacement and multiple isomorphous replacement methods
- 1 August 1991
- journal article
- Published by International Union of Crystallography (IUCr) in Acta crystallographica Section B, Structural science, crystal engineering and materials
- Vol. 47 (4) , 527-535
- https://doi.org/10.1107/s0108768191001908
Abstract
The crystal structure of Aspergillus niger acid alpha-amylase was solved by a combination of multiple isomorphous replacement and molecular replacement methods. The atomic coordinates of Aspergillus oryzae (TAKA) alpha-amylase (entry 2TAA in the Protein Data Bank) and experimental diffraction data from a new monoclinic crystal form of TAKA alpha-amylase, were used during the procedure. Sequence identity between the two proteins is approximately 80%. The atomic parameters derived from the molecular replacement solution were too inaccurate to initiate least-squares crystallographic refinement. The molecular model was extensively revised against the experimental electron density map calculated at 3 A resolution. Subsequent crystallographic refinement of this model using synchrotron data to 2.1 A resolution led to a conventional R factor of 16.8%. The structure conforms well to expected stereochemistry with bond lengths deviating from target values by 0.031 A, and planar groups showing a root-mean-square deviation from ideal planes of 0.025 A.Keywords
This publication has 0 references indexed in Scilit: