1KNT: The 1.6 Angstroms Structure Of The Kunitz-Type Domain From The Alpha3 Chain Of The Human Type Vi Collagen

The C-terminal Kunitz-type domain from the alpha 3 chain of human type VI collagen (C5), a single 58 amino acid residue chain with three disulfide bridges, was cloned, expressed and crystallized in a monoclonic form, space group P2(1), with a = 25.7 A, b = 38.2 A, c = 28.8 A and beta = 109 degrees. The structure was resolved by molecular replacement, using Alzheimer's protein precursor inhibitor and bovine pancreatic trypsin inhibitor three-dimensional structures as search models. The molecule with one sulfate ion and 43 associated water molecules was refined by XPLOR to an R-factor of 18.9% at 1.6 A. The molecule was not degraded by trypsin and did not inhibit trypsin or tested serine proteases. As opposed to the other Kunitz family members, C5 demonstrates left-handed chirality of the Cys14-Cys38 disulfide bond. Inversion of the Thr13 carbonyl and bulky side-chains at the interface with trypsin in a model of the C5-trypsin complex may explain the lack of inhibition of trypsin.
PDB ID: 1KNTDownload
MMDB ID: 49985
PDB Deposition Date: 1994/8/18
Updated in MMDB: 2007/10
Experimental Method:
x-ray diffraction
Resolution: 1.6  Å
Source Organism:
Similar Structures:
Biological Unit for 1KNT: monomeric; determined by author
Molecular Components in 1KNT
Label Count Molecule
Protein (1 molecule)
Collagen Type VI(Gene symbol: COL6A3)
Molecule annotation
Chemical (1 molecule)
* Click molecule labels to explore molecular sequence information.

Citing MMDB