9PQP: Maltose/maltodextrin-binding periplasmic protein

Crystal structure of maltose binding protein (Apo), mutant Trp340 to 4-Fluorotryptophan. Determined by X-ray diffraction at 1.07 Å resolution. Released 5 Aug 2026.

Method: X-ray diffraction
Resolution: 1.07 Å
Organism: Escherichia coli
Chains: 1
Atoms: 3,987
Mol. weight: 42.35 kDa
Ligands: CD
Released: 5 Aug 2026

Explore 9PQP in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

9PQP contains 24 α-helices and 26 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: 24 helices, 26 β-strands

Element	Residues	Length	Sheet
α-helix	2-3	2
β-strand	7-10	4	1
α-helix	17-31	15
β-strand	35-38	4	1
α-helix	43-52	10
β-strand	59-63	5	1
α-helix	64-72	9
β-strand	76	1	2
α-helix	77-79	3
α-helix	83-86	4
β-strand	89	1	3
α-helix	91-95	5
β-strand	98-99	2	4
β-strand	102-103	2	4
β-strand	106-111	6	1
β-strand	114-118	5	5
β-strand	128	1	6
α-helix	132-141	10
β-strand	147	1	5
α-helix	154-163	10
β-strand	167	1	7
β-strand	170-172	3	8
β-strand	175-177	3	8
β-strand	182	1	7
α-helix	186-200	15
α-helix	210-218	9
β-strand	224-227	4	5
α-helix	229-231	3
α-helix	232-238	7
β-strand	242-245	4	5
α-helix	246-248	3
β-strand	249	1	6
β-strand	250	1	9
β-strand	253	1	9
α-helix	254-255	2
β-strand	258-259	2	10
β-strand	260-266	7	1
β-strand	267	1	2
α-helix	273-279	7
α-helix	280-284	5
α-helix	287-296	10
β-strand	301-302	2	1
β-strand	304	1	3
α-helix	305-311	7
α-helix	315-326	12
β-strand	328-329	2	10
α-helix	330-331	2
α-helix	334-338	5
α-helix	339-352	14
α-helix	357-369	13

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Maltose/maltodextrin-binding periplasmic protein	A	protein	370	Escherichia coli	P0AEY0 (AlphaFold model)

Sequence of entity 1 (A), FASTA

>9PQP_1 Maltose/maltodextrin-binding periplasmic protein (chains A)
KIEEGKLVIWINGDKGYNGLAEVGKKFEKDTGIKVTVEHPDKLEEKFPQVAATGDGPDII
FWAHDRFGGYAQSGLLAEITPDKAFQDKLYPFTWDAVRYNGKLIAYPIAVEALSLIYNKD
LLPNPPKTWEEIPALDKELKAKGKSALMFNLQEPYFTWPLIAADGGYAFKYENGKYDIKD
VGVDNAGAKAGLTFLVDLIKNKHMNADTDYSIAEAAFNKGETAMTINGPWAWSNIDTSKV
NYGVTVLPTFKGQPSKPFVGVLSAGINAASPNKELAKEFLENYLLTDEGLEAVNKDKPLG
AVALKSYEEELAKDPRIAATMENAQKGEIMPNIPQMSAFWYAVRTAVINAASGRQAVDEA
LKDAQTRITK

Ligands and cofactors

ID	Name	Formula	Copies
CD	Cadmium ion	Cd	11

Water and common crystallization additives (PEG, PG4, NA) are not listed.

Primary citation

Structural accomodations of tryptophan 4-substitutions in maltose binding protein. Habel, E., Huber, T. To be published.

Other PDB entries of the same protein (UniProt P0AEY0 (AlphaFold model), which also has an AlphaFold model), best resolution first:

9PQL 1.37 Å, Crystal structure of maltose binding protein (Apo), mutant Trp62 to 4-Fluorotryptophan
9PQN 1.37 Å, Crystal structure of maltose binding protein (Apo), mutant Trp340 to 4-Cyanotryptophan
9TY2 1.75 Å, Crystal structure of a Picomolar Nanobody in complex with Maltose Binding Protein, MBP,…
4WGI 1.85 Å, A Single Diastereomer of a Macrolactam Core Binds Specifically to Myeloid Cell Leukemia…
9PQK 1.87 Å, Crystal structure of maltose binding protein (Apo), mutant Trp10 to 4-Fluorotryptophan
4WVI 1.9 Å, Crystal structure of the Type-I signal peptidase from Staphylococcus aureus (SpsB) in…
4WVJ 1.95 Å, Crystal structure of the Type-I signal peptidase from Staphylococcus aureus (SpsB) in…
4YS9 2.0 Å, Ataxin-3 Carboxy-Terminal Region - Crystal C1 (tetragonal)
5II4 2.0 Å, Crystal structure of red abalone VERL repeat 1 with linker at 2.0 A resolution
5JON 2.04 Å, Crystal structure of the unliganded form of HCN2 CNBD
4WVG 2.05 Å, Crystal structure of the Type-I signal peptidase from Staphylococcus aureus (SpsB).
3VD8 2.07 Å, Crystal structure of human AIM2 PYD domain with MBP fusion

Browse structure collections

About this viewer

MolViewer shows 9PQP directly in your browser with nothing to install. Switch between cartoon, ball-and-stick, spacefill and surface views, color by chain, secondary structure or B-factor, measure distances, angles and dihedrals, and share or embed the view.