3iwm

The octameric SARS-CoV main protease

Method: X-RAY DIFFRACTION

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

3C-like proteinase

SARS coronavirus

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein heterocomplex	Heteromer	Protein 16	;N-[(5-METHYLISOXAZOL-3-YL)CARBONYL]ALANYL-L-VALYL-N~1~-((1R,2Z)-4-(BENZYLOXY)-4-OXO-1-{[(3R)-2-OXOPYRROLIDIN-3-YL]METHYL}BUT-2-ENYL)-L-LEUCINAMIDE ; × 8	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	R1A_CVHSA
Isoform	—
PDB entities	1
Chains and sequence ranges	Author chain A； PDBConstruct 1–306； UniProt 3241–3546 Author chain B； PDBConstruct 1–306； UniProt 3241–3546 Author chain C； PDBConstruct 1–306； UniProt 3241–3546 Author chain D； PDBConstruct 1–306； UniProt 3241–3546

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	3iwm
Deposition date deposition_date	2009-09-02
Structure title title	The octameric SARS-CoV main protease
Keywords keywords	SARS-CoV, main protease, octamer, active conformation, 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.

3iwm__assembly_1__model_1

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

Download this curve (.dat)

3iwm__assembly_1__model_1 | I(q)

100 plotted points; both axes use logarithmic scales.

3iwm__assembly_1__model_1 | P(r) · Pending

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

Rg（Guinier）	48.68 Å
Rg (electron density)	47.90 Å
Total Rg	48.16 Å
Atom count	19024
Residues	2428
Excluded volume	338190 Å³
Maximum q	0.500 Å⁻¹

Assembly	Model	Structure unit	Oligomeric description	Status	CRYSOL	Actions
1	1	`3iwm__assembly_1__model_1`	hexadecameric （16）	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 (2)

Entity 1 Entity 1 polymer

Description description	3C-like proteinase
Molecular weight formula_weight	33876.6 kDa
EC 编号 ec_number	3.4.22.-
Source method src_method	man
Copy count entity_count	4

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	A,B,C,D
Atom count atom_count	9512

SGFRKMAFPSGKVEGCMVQVTCGTTTLNGLWLDDTVYCPRHVICTAEDMLNPNYEDLLIRKSNHSFLVQAGNVQLRVIGHSMQNCLLRLKVDTSNPKTPKYKFVRIQPGQTFSVLACYNGSPSGVYQCAMRPNHTIKGSFLNGSCGSVGFNIDYDCVSFCYMHHMELPTGVHAGTDLEGKFYGPFVDRQTAQAAGTDTTITLNVLAWLYAAVINGDRWFLNRFTTTLNDFNLVAMKYNYEPLTQDHVDILGPLSAQTGIAVLDMCAALKELLQNGMNGRTILGSTILEDEFTPFDVVRQCSGVTFQ

Source Source

Source organism organism	SARS coronavirus
Common name common_name	SARS-CoV
NCBI taxonomy ID ncbi_taxonomy_id	227859
Host organism host_organism	Escherichia coli

Entity 2 Entity 2 polymer

Description description	;N-[(5-METHYLISOXAZOL-3-YL)CARBONYL]ALANYL-L-VALYL-N~1~-((1R,2Z)-4-(BENZYLOXY)-4-OXO-1-{[(3R)-2-OXOPYRROLIDIN-3-YL]METHYL}BUT-2-ENYL)-L-LEUCINAMIDE ;
Molecular weight formula_weight	680.8 kDa
Source method src_method	syn
Copy count entity_count	4

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	H,F,G,E

XAVLXX

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6. Fold Classification (SCOP + CATH) 12 domains

CATH v4.4 (12 domains)

Domain ID domain_id	3iwmA01
Class class	2 — Mainly Beta
Architecture architecture	40 — Beta Barrel
Topology topology	10 — Thrombin, subunit H
Homologous superfamily homologous superfamily	10 — Trypsin-like serine proteases

Domain ID domain_id	3iwmA02
Class class	2 — Mainly Beta
Architecture architecture	40 — Beta Barrel
Topology topology	10 — Thrombin, subunit H
Homologous superfamily homologous superfamily	10 — Trypsin-like serine proteases

Domain ID domain_id	3iwmA03
Class class	1 — Mainly Alpha
Architecture architecture	10 — Orthogonal Bundle
Topology topology	1840 — main proteinase (3clpro) structure, domain 3
Homologous superfamily homologous superfamily	10 — main proteinase (3clpro) structure, domain 3

Domain ID domain_id	3iwmB01
Class class	2 — Mainly Beta
Architecture architecture	40 — Beta Barrel
Topology topology	10 — Thrombin, subunit H
Homologous superfamily homologous superfamily	10 — Trypsin-like serine proteases

Domain ID domain_id	3iwmB02
Class class	2 — Mainly Beta
Architecture architecture	40 — Beta Barrel
Topology topology	10 — Thrombin, subunit H
Homologous superfamily homologous superfamily	10 — Trypsin-like serine proteases

Domain ID domain_id	3iwmB03
Class class	1 — Mainly Alpha
Architecture architecture	10 — Orthogonal Bundle
Topology topology	1840 — main proteinase (3clpro) structure, domain 3
Homologous superfamily homologous superfamily	10 — main proteinase (3clpro) structure, domain 3

Domain ID domain_id	3iwmC01
Class class	2 — Mainly Beta
Architecture architecture	40 — Beta Barrel
Topology topology	10 — Thrombin, subunit H
Homologous superfamily homologous superfamily	10 — Trypsin-like serine proteases

Domain ID domain_id	3iwmC02
Class class	2 — Mainly Beta
Architecture architecture	40 — Beta Barrel
Topology topology	10 — Thrombin, subunit H
Homologous superfamily homologous superfamily	10 — Trypsin-like serine proteases

Domain ID domain_id	3iwmC03
Class class	1 — Mainly Alpha
Architecture architecture	10 — Orthogonal Bundle
Topology topology	1840 — main proteinase (3clpro) structure, domain 3
Homologous superfamily homologous superfamily	10 — main proteinase (3clpro) structure, domain 3

Domain ID domain_id	3iwmD01
Class class	2 — Mainly Beta
Architecture architecture	40 — Beta Barrel
Topology topology	10 — Thrombin, subunit H
Homologous superfamily homologous superfamily	10 — Trypsin-like serine proteases

Domain ID domain_id	3iwmD02
Class class	2 — Mainly Beta
Architecture architecture	40 — Beta Barrel
Topology topology	10 — Thrombin, subunit H
Homologous superfamily homologous superfamily	10 — Trypsin-like serine proteases

Domain ID domain_id	3iwmD03
Class class	1 — Mainly Alpha
Architecture architecture	10 — Orthogonal Bundle
Topology topology	1840 — main proteinase (3clpro) structure, domain 3
Homologous superfamily homologous superfamily	10 — main proteinase (3clpro) structure, domain 3

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Unit-cell length a length_a	161.930 Å
Unit-cell length b length_b	161.930 Å
Unit-cell length c length_c	166.435 Å
Unit-cell angle α angle_alpha	90.00 °
Unit-cell angle β angle_beta	90.00 °
Unit-cell angle γ angle_gamma	90.00 °
Molecules per unit cell Z z_pdb	32

Space group space_group	P 41 21 2
Space-group number int_tables_number	92
Crystal system crystal_system	—

Resolution resolution	3.200 Å
Low-resolution limit resolution_low	48.943 Å
R factor r_factor	0.2230
R_work r_work	0.2204
R_free r_free	0.2721

The octameric SARS-CoV main protease

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

3C-like proteinase

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

3iwm__assembly_1__model_1

3iwm__assembly_1__model_1 | I(q)

3iwm__assembly_1__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 (2)

Entity 1 Entity 1 polymer

Polymer Polymer

Source Source

Entity 2 Entity 2 polymer

Polymer Polymer

6. Fold Classification (SCOP + CATH) 12 domains

CATH v4.4 (12 domains)

7. Citations (1)

The octameric SARS-CoV main protease

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

3C-like proteinase

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

3iwm__assembly_1__model_1

3iwm__assembly_1__model_1 | I(q)

3iwm__assembly_1__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 (2)

Entity 1 Entity 1 polymer

Polymer Polymer

Source Source

Entity 2 Entity 2 polymer

Polymer Polymer

6. Fold Classification (SCOP + CATH) 12 domains

CATH v4.4 (12 domains)

7. Citations (1)