|3cpa, resolution 2.00Å ()|
X-RAY CRYSTALLOGRAPHIC INVESTIGATION OF SUBSTRATE BINDING TO CARBOXYPEPTIDASE A AT SUBZERO TEMPERATURE
A high-resolution x-ray crystallographic investigation of the complex between carboxypeptidase A (CPA; peptidyl-L-amino-acid hydrolase, EC 18.104.22.168) and the slowly hydrolyzed substrate glycyl-L-tyrosine was done at -9 degrees C. Although this enzyme-substrate complex has been the subject of earlier crystallographic investigation, a higher resolution electron-density map of the complex with greater occupancy of the substrate was desired. All crystal chemistry (i.e., crystal soaking and x-ray data collection) was performed on a diffractometer-mounted flow cell, in which the crystal was immobilized. The x-ray data to 1.6-A resolution have yielded a well-resolved structure in which the zinc ion of the active site is five-coordinate: three enzyme residues (glutamate-72, histidine-69, and histidine-196) and the carbonyl oxygen and amino terminus of glycyl-L-tyrosine complete the coordination polyhedron of the metal. These results confirm that this substrate may be bound in a nonproductive manner, because the hydrolytically important zinc-bound water has been displaced and excluded from the active site. It is likely that all dipeptide substrates of carboxypeptidase A that carry an unprotected amino terminus are poor substrates because of such favorable bidentate coordination to the metal ion of the active site.
X-ray crystallographic investigation of substrate binding to carboxypeptidase A at subzero temperature., Christianson DW, Lipscomb WN, Proc Natl Acad Sci U S A. 1986 Oct;83(20):7568-72. PMID:3463986
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
About this Structure
3cpa is a 1 chain structure with sequence from Bos taurus. This structure supersedes the now removed PDB entry 1cpa. The October 2011 RCSB PDB Molecule of the Month feature on PDB Pioneers by David Goodsell is 10.2210/rcsb_pdb/mom_2011_10. Full crystallographic information is available from OCA.
- Christianson DW, Lipscomb WN. X-ray crystallographic investigation of substrate binding to carboxypeptidase A at subzero temperature. Proc Natl Acad Sci U S A. 1986 Oct;83(20):7568-72. PMID:3463986