3CPA

X-RAY CRYSTALLOGRAPHIC INVESTIGATION OF SUBSTRATE BINDING TO CARBOXYPEPTIDASE A AT SUBZERO TEMPERATURE

Replaces:  1CPA

Summary for 3CPA

• Entry DOI: 10.2210/pdb3cpa/pdb
• Descriptor: CARBOXYPEPTIDASE A, GLYCINE, TYROSINE, ... (4 entities in total)
• Functional Keywords: hydrolase (c-terminal peptidase)
• Biological source: Bos taurus (bovine)
• Cellular location: Secreted, extracellular space: P00730
• Total number of polymer chains: 1
• Total formula weight: 34764.13

Authors

Lipscomb, W.N. (deposition date: 1982-03-24, release date: 1982-07-29, Last modification date: 2024-10-16)

Primary citation

Christianson, D.W.,Lipscomb, W.N.
X-ray crystallographic investigation of substrate binding to carboxypeptidase A at subzero temperature.
Proc.Natl.Acad.Sci.USA, 83:7568-7572, 1986

PubMed Abstract: A high-resolution x-ray crystallographic investigation of the complex between carboxypeptidase A (CPA; peptidyl-L-amino-acid hydrolase, EC 3.4.17.1) 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.

PubMed: 3463986
DOI: 10.1073/pnas.83.20.7568

Experimental method

X-RAY DIFFRACTION (2 Å)