5k1i

PDE4 crystal structure in complex with small molecule inhibitor

Method: X-RAY DIFFRACTION

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1. Protein Identity and Related Structures Protein Identity & Related Structures

;cAMP-specific 3',5'-cyclic phosphodiesterase 4D ;

Homo sapiens

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein monomer	Monomer	Protein 1	4-[(5-acetyl-2-ethyl-3-oxo-6-phenyl-2,3-dihydropyridazin-4-yl)amino]benzoic acid × 1 ZINC ION × 1 MAGNESIUM ION × 1 water × 1	Consistent with protein count
2	Protein monomer	Monomer	Protein 1	4-[(5-acetyl-2-ethyl-3-oxo-6-phenyl-2,3-dihydropyridazin-4-yl)amino]benzoic acid × 1 ZINC ION × 1 MAGNESIUM ION × 1 water × 1	Consistent with protein count
3	Protein monomer	Monomer	Protein 1	4-[(5-acetyl-2-ethyl-3-oxo-6-phenyl-2,3-dihydropyridazin-4-yl)amino]benzoic acid × 1 ZINC ION × 1 MAGNESIUM ION × 1 water × 1	Consistent with protein count
4	Protein monomer	Monomer	Protein 1	4-[(5-acetyl-2-ethyl-3-oxo-6-phenyl-2,3-dihydropyridazin-4-yl)amino]benzoic acid × 1 ZINC ION × 1 MAGNESIUM ION × 1 water × 1	Consistent with protein count
5	Protein monomer	Monomer	Protein 1	4-[(5-acetyl-2-ethyl-3-oxo-6-phenyl-2,3-dihydropyridazin-4-yl)amino]benzoic acid × 1 ZINC ION × 1 MAGNESIUM ION × 1 water × 1	Consistent with protein count
6	Protein monomer	Monomer	Protein 1	4-[(5-acetyl-2-ethyl-3-oxo-6-phenyl-2,3-dihydropyridazin-4-yl)amino]benzoic acid × 1 ZINC ION × 1 MAGNESIUM ION × 1 water × 1	Consistent with protein count
7	Protein monomer	Monomer	Protein 1	4-[(5-acetyl-2-ethyl-3-oxo-6-phenyl-2,3-dihydropyridazin-4-yl)amino]benzoic acid × 1 ZINC ION × 1 MAGNESIUM ION × 1 water × 1	Consistent with protein count
8	Protein monomer	Monomer	Protein 1	4-[(5-acetyl-2-ethyl-3-oxo-6-phenyl-2,3-dihydropyridazin-4-yl)amino]benzoic acid × 1 ZINC ION × 1 MAGNESIUM ION × 1 water × 1	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	PDE4D_HUMAN
Isoform	—
PDB entities	1
Chains and sequence ranges	Author chain A； PDBConstruct 1–326； UniProt 388–713 Author chain B； PDBConstruct 1–326； UniProt 388–713 Author chain C； PDBConstruct 1–326； UniProt 388–713 Author chain D； PDBConstruct 1–326； UniProt 388–713 Author chain E； PDBConstruct 1–326； UniProt 388–713 Author chain F； PDBConstruct 1–326； UniProt 388–713 Author chain G； PDBConstruct 1–326； UniProt 388–713 Author chain H； PDBConstruct 1–326； UniProt 388–713

The page prioritizes protein identity, the current assembly, associated components, oligomeric state and cross-PDB links. Chain mapping and sequence ranges are retained as data evidence. Internal IDs, import timestamps and assembly operation expressions are maintenance fields and are not shown here.

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2. Structure Basics 2. Structure Basics

Entry ID entry_id	5k1i
Deposition date deposition_date	2016-05-18
Structure title title	PDE4 crystal structure in complex with small molecule inhibitor
Keywords keywords	phosphodiesterases, inhibitor, Hydrolase; HYDROLASE
Experimental Method method	X-RAY DIFFRACTION

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3. Official assembly/model SAXS Official SAXS Profiles

This page reads only the latest assembly calculations. Every curve maps to an explicit PDB entry, official biological assembly and coordinate model.

5k1i__assembly_2__model_1

Assembly 2 · Model 1 · CRYSOL 4.1.3-1-20251215 (887e7ef)

Download this curve (.dat)

5k1i__assembly_2__model_1 | I(q)

100 plotted points; both axes use logarithmic scales.

5k1i__assembly_2__model_1 | P(r) · Pending

P(r) will be calculated and displayed separately for the same assembly/model.

Rg（Guinier）	20.82 Å
Rg (electron density)	19.54 Å
Total Rg	20.54 Å
Atom count	2667
Residues	326
Excluded volume	47378 Å³
Maximum q	0.500 Å⁻¹

Assembly	Model	Structure unit	Oligomeric description	Status	CRYSOL	Actions
1	1	`5k1i__assembly_1__model_1`	monomeric （1）	Success	4.1.3-1-20251215 (887e7ef)	View Download
2	1	`5k1i__assembly_2__model_1`	monomeric （1）	Success	4.1.3-1-20251215 (887e7ef)	View Download
3	1	`5k1i__assembly_3__model_1`	monomeric （1）	Success	4.1.3-1-20251215 (887e7ef)	View Download
4	1	`5k1i__assembly_4__model_1`	monomeric （1）	Success	4.1.3-1-20251215 (887e7ef)	View Download
5	1	`5k1i__assembly_5__model_1`	monomeric （1）	Success	4.1.3-1-20251215 (887e7ef)	View Download
6	1	`5k1i__assembly_6__model_1`	monomeric （1）	Success	4.1.3-1-20251215 (887e7ef)	View Download
7	1	`5k1i__assembly_7__model_1`	monomeric （1）	Success	4.1.3-1-20251215 (887e7ef)	View Download
8	1	`5k1i__assembly_8__model_1`	monomeric （1）	Success	4.1.3-1-20251215 (887e7ef)	View Download

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4. Crystallography and Experiment 4. Crystallography & Experiment

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5. Entities and Polymers Entities & Polymers (5)

Entity 1 Entity 1 polymer

Description description	;cAMP-specific 3',5'-cyclic phosphodiesterase 4D ;
Molecular weight formula_weight	37578.6 kDa
EC 编号 ec_number	3.1.4.53
Source method src_method	man
Copy count entity_count	8

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	A,B,C,D,E,F,G,H
Atom count atom_count	21443

TEQEDVLAKELEDVNKWGLHVFRIAELSGNRPLTVIMHTIFQERDLLKTFKIPVDTLITYLMTLEDHYHADVAYHNNIHAADVVQSTHVLLSTPALEAVFTDLEILAAIFASAIHDVDHPGVSNQFLINTNSELALMYNDSSVLENHHLAVGFKLLQEENCDIFQNLTKKQRQSLRKMVIDIVLATDMSKHMNLLADLKTMVETKKVTSSGVLLLDNYSDRIQVLQNMVHCADLSNPTKPLQLYRQWTDRIMEEFFRQGDRERERGMEISPMCDKHNASVEKSQVGFIDYIVHPLWETWADLVHPDAQDILDTLEDNREWYQSTIP

Source Source

Source organism organism	Homo sapiens
Common name common_name	Human
NCBI taxonomy ID ncbi_taxonomy_id	9606
Host organism host_organism	Escherichia coli BL21(DE3)

Entity 2 Entity 2 non-polymer

Description description	4-[(5-acetyl-2-ethyl-3-oxo-6-phenyl-2,3-dihydropyridazin-4-yl)amino]benzoic acid
Molecular weight formula_weight	377.4 kDa
Source method src_method	syn
Copy count entity_count	8

Entity 3 Entity 3 non-polymer

Description description	ZINC ION
Molecular weight formula_weight	65.4 kDa
Source method src_method	syn
Copy count entity_count	8

Entity 4 Entity 4 non-polymer

Description description	MAGNESIUM ION
Molecular weight formula_weight	24.3 kDa
Source method src_method	syn
Copy count entity_count	8

Entity 5 Entity 5 water

Description description	water
Molecular weight formula_weight	18.0 kDa
Source method src_method	nat
Copy count entity_count	210

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6. Fold Classification (SCOP + CATH) 16 domains

SCOP 2.08 (8 domains)

Domain ID domain_id	d5k1ia_
Class class	a — All alpha proteins
Fold Fold fold	a.211 — HD-domain/PDEase-like
Superfamily Superfamily superfamily	a.211.1 — HD-domain/PDEase-like
Family Family family	a.211.1.2 — PDEase

Domain ID domain_id	d5k1ib_
Class class	a — All alpha proteins
Fold Fold fold	a.211 — HD-domain/PDEase-like
Superfamily Superfamily superfamily	a.211.1 — HD-domain/PDEase-like
Family Family family	a.211.1.2 — PDEase

Domain ID domain_id	d5k1ic_
Class class	a — All alpha proteins
Fold Fold fold	a.211 — HD-domain/PDEase-like
Superfamily Superfamily superfamily	a.211.1 — HD-domain/PDEase-like
Family Family family	a.211.1.2 — PDEase

Domain ID domain_id	d5k1id_
Class class	a — All alpha proteins
Fold Fold fold	a.211 — HD-domain/PDEase-like
Superfamily Superfamily superfamily	a.211.1 — HD-domain/PDEase-like
Family Family family	a.211.1.2 — PDEase

Domain ID domain_id	d5k1ie_
Class class	a — All alpha proteins
Fold Fold fold	a.211 — HD-domain/PDEase-like
Superfamily Superfamily superfamily	a.211.1 — HD-domain/PDEase-like
Family Family family	a.211.1.2 — PDEase

Domain ID domain_id	d5k1if_
Class class	a — All alpha proteins
Fold Fold fold	a.211 — HD-domain/PDEase-like
Superfamily Superfamily superfamily	a.211.1 — HD-domain/PDEase-like
Family Family family	a.211.1.2 — PDEase

Domain ID domain_id	d5k1ig_
Class class	a — All alpha proteins
Fold Fold fold	a.211 — HD-domain/PDEase-like
Superfamily Superfamily superfamily	a.211.1 — HD-domain/PDEase-like
Family Family family	a.211.1.2 — PDEase

Domain ID domain_id	d5k1ih_
Class class	a — All alpha proteins
Fold Fold fold	a.211 — HD-domain/PDEase-like
Superfamily Superfamily superfamily	a.211.1 — HD-domain/PDEase-like
Family Family family	a.211.1.2 — PDEase

CATH v4.4 (8 domains)

Domain ID domain_id	5k1iA00
Class class	1 — Mainly Alpha
Architecture architecture	10 — Orthogonal Bundle
Topology topology	1300 — Catalytic domain of cyclic nucleotide phosphodiesterase 4b2b
Homologous superfamily homologous superfamily	10 — 3'5'-cyclic nucleotide phosphodiesterase, catalytic domain

Domain ID domain_id	5k1iB00
Class class	1 — Mainly Alpha
Architecture architecture	10 — Orthogonal Bundle
Topology topology	1300 — Catalytic domain of cyclic nucleotide phosphodiesterase 4b2b
Homologous superfamily homologous superfamily	10 — 3'5'-cyclic nucleotide phosphodiesterase, catalytic domain

Domain ID domain_id	5k1iC00
Class class	1 — Mainly Alpha
Architecture architecture	10 — Orthogonal Bundle
Topology topology	1300 — Catalytic domain of cyclic nucleotide phosphodiesterase 4b2b
Homologous superfamily homologous superfamily	10 — 3'5'-cyclic nucleotide phosphodiesterase, catalytic domain

Domain ID domain_id	5k1iD00
Class class	1 — Mainly Alpha
Architecture architecture	10 — Orthogonal Bundle
Topology topology	1300 — Catalytic domain of cyclic nucleotide phosphodiesterase 4b2b
Homologous superfamily homologous superfamily	10 — 3'5'-cyclic nucleotide phosphodiesterase, catalytic domain

Domain ID domain_id	5k1iE00
Class class	1 — Mainly Alpha
Architecture architecture	10 — Orthogonal Bundle
Topology topology	1300 — Catalytic domain of cyclic nucleotide phosphodiesterase 4b2b
Homologous superfamily homologous superfamily	10 — 3'5'-cyclic nucleotide phosphodiesterase, catalytic domain

Domain ID domain_id	5k1iF00
Class class	1 — Mainly Alpha
Architecture architecture	10 — Orthogonal Bundle
Topology topology	1300 — Catalytic domain of cyclic nucleotide phosphodiesterase 4b2b
Homologous superfamily homologous superfamily	10 — 3'5'-cyclic nucleotide phosphodiesterase, catalytic domain

Domain ID domain_id	5k1iG00
Class class	1 — Mainly Alpha
Architecture architecture	10 — Orthogonal Bundle
Topology topology	1300 — Catalytic domain of cyclic nucleotide phosphodiesterase 4b2b
Homologous superfamily homologous superfamily	10 — 3'5'-cyclic nucleotide phosphodiesterase, catalytic domain

Domain ID domain_id	5k1iH00
Class class	1 — Mainly Alpha
Architecture architecture	10 — Orthogonal Bundle
Topology topology	1300 — Catalytic domain of cyclic nucleotide phosphodiesterase 4b2b
Homologous superfamily homologous superfamily	10 — 3'5'-cyclic nucleotide phosphodiesterase, catalytic domain

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Unit-cell length a length_a	61.444 Å
Unit-cell length b length_b	78.347 Å
Unit-cell length c length_c	161.756 Å
Unit-cell angle α angle_alpha	91.01 °
Unit-cell angle β angle_beta	92.79 °
Unit-cell angle γ angle_gamma	90.08 °
Molecules per unit cell Z z_pdb	8

Space group space_group	P 1
Space-group number int_tables_number	1
Crystal system crystal_system	—

Resolution resolution	2.610 Å
Low-resolution limit resolution_low	25.000 Å
R factor r_factor	0.1947
R_work r_work	0.1913
R_free r_free	0.2583

PDE4 crystal structure in complex with small molecule inhibitor

1. Protein Identity and Related Structures Protein Identity & Related Structures

;cAMP-specific 3',5'-cyclic phosphodiesterase 4D ;

State in the Current Structure

Other States of the Same Protein in the Database

2. Structure Basics 2. Structure Basics

3. Official assembly/model SAXS Official SAXS Profiles

5k1i__assembly_2__model_1

5k1i__assembly_2__model_1 | I(q)

5k1i__assembly_2__model_1 | P(r) · Pending

4. Crystallography and Experiment 4. Crystallography & Experiment

Unit cell Unit Cell

Symmetry Symmetry

Refinement Refinement

Diffraction experiment Diffraction

5. Entities and Polymers Entities & Polymers (5)

Entity 1 Entity 1 polymer

Polymer Polymer

Source Source

Entity 2 Entity 2 non-polymer

Entity 3 Entity 3 non-polymer

Entity 4 Entity 4 non-polymer

Entity 5 Entity 5 water

6. Fold Classification (SCOP + CATH) 16 domains

SCOP 2.08 (8 domains)

CATH v4.4 (8 domains)

7. Citations (1)

PDE4 crystal structure in complex with small molecule inhibitor

1. Protein Identity and Related Structures Protein Identity & Related Structures

;cAMP-specific 3',5'-cyclic phosphodiesterase 4D ;

State in the Current Structure

Other States of the Same Protein in the Database

Monomer

Homodimer

Homotetramer

Other homooligomers

Heteromeric or nucleic-acid complex

2. Structure Basics 2. Structure Basics

3. Official assembly/model SAXS Official SAXS Profiles

5k1i__assembly_2__model_1

5k1i__assembly_2__model_1 | I(q)

5k1i__assembly_2__model_1 | P(r) · Pending

4. Crystallography and Experiment 4. Crystallography & Experiment

Unit cell Unit Cell

Symmetry Symmetry

Refinement Refinement

Diffraction experiment Diffraction

5. Entities and Polymers Entities & Polymers (5)

Entity 1 Entity 1 polymer

Polymer Polymer

Source Source

Entity 2 Entity 2 non-polymer

Entity 3 Entity 3 non-polymer

Entity 4 Entity 4 non-polymer

Entity 5 Entity 5 water

6. Fold Classification (SCOP + CATH) 16 domains

SCOP 2.08 (8 domains)

CATH v4.4 (8 domains)

7. Citations (1)