1BIK: Bikunin

X-ray structure of bikunin from the human inter-alpha-inhibitor complex. Determined by X-ray diffraction at 2.5 Å resolution. Released 16 Mar 1999.

Method: X-ray diffraction
Resolution: 2.5 Å
Organism: Homo sapiens
Chains: 1
Atoms: 884
Mol. weight: 16.4 kDa
Ligands: NAG
Released: 16 Mar 1999

Explore 1BIK in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

1BIK contains 4 α-helices and 6 β-strands across 1 chain. Residue ranges use author residue numbering, as in the PDB file, from PDBe. To see them in 3D, choose the Cartoon representation with Secondary structure coloring: helices, sheets and coils get different colors.

Chain A: 4 helices, 6 β-strands

Element	Residues	Length	Sheet
α-helix	29-30	2
β-strand	39-45	7	1
β-strand	50-56	7	1
β-strand	66	1	1
α-helix	69-76	8
α-helix	79-83	5
β-strand	95-101	7	2
β-strand	106-112	7	2
β-strand	122	1	2
α-helix	125-132	8

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Bikunin	A	protein	147	Homo sapiens	P02760 (AlphaFold model)

Sequence of entity 1 (A), FASTA

>1BIK_1 BIKUNIN (chains A)
AVLPQEEEGSGGGQLVTEVTKKEDSCQLGYSAGPCMGMTSRYFYNGTSMACETFQYGGCM
GNGNNFVTEKECLQTCRTVAACNLPIVRGPCRAFIQLWAFDAVKGKCVLFPYGGCQGNGN
KFYSEKECREYCGVPGDGDEELLRFSN

Ligands and cofactors

ID	Name	Formula	Copies
NAG	2-acetamido-2-deoxy-beta-D-glucopyranose	C8 H15 N O6	1

Water and common crystallization additives (SO4) are not listed.

Primary citation

The crystal structure of bikunin from the inter-alpha-inhibitor complex: a serine protease inhibitor with two Kunitz domains. Xu, Y., Carr, P.D., Guss, J.M. et al. J Mol Biol (1998) 276:955-966. DOI 10.1006/jmbi.1997.1582 · PubMed

Other PDB entries of the same protein (UniProt P02760 (AlphaFold model), which also has an AlphaFold model), best resolution first:

6EJA 1.94 Å, Human Xylosyltransferase 1 in complex with peptide QEEEYSGGGQGG
6EJ7 2.0 Å, Human Xylosyltransferase 1 in complex with UDP-xylose and peptide QEEEGAGGGQGG
4ES7 2.0 Å, crystal structure of protein HC from Homo sapiens at 2 angstrom
6EJ9 2.02 Å, Human Xylosyltransferase 1 in complex with peptide QEPEGSGGGQGG
6EJC 2.06 Å, Human Xylosyltransferase 1 in complex with peptide QEEEGSGVGQGG
6EJ8 2.09 Å, Human Xylosyltransferase 1 in complex with peptide QEEEGSGGGQGG
3QKG 2.3 Å, Crystal structure of alpha-1-microglobulin at 2.3 A resolution
4U30 2.5 Å, Human mesotrypsin complexed with bikunin Kunitz domain 2
6EJB 2.56 Å, Human Xylosyltransferase 1 in complex with peptide QEEEGSAGGQGG
6EJD 2.68 Å, Human Xylosyltransferase 1 in complex with peptide QEEEGSGGPQGG

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