1q9l

S25-2 Fab Unliganded 2

Method: X-RAY DIFFRACTION

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

No usable UniProt protein identity is available for this entry.

The relationship tables retain this entry's assembly and composition data, but cross-PDB links for the same protein cannot be established reliably without a unified protein identity.

Assembly Composition of the Current Entry

Assembly	Physical composition	Protein state	蛋白 / DNA / RNA / 其他Polymer	Data consistency
1	Protein heterocomplex	Heteromer	2 / 0 / 0 / 0	Consistent with protein count
2	Protein heterocomplex	Heteromer	2 / 0 / 0 / 0	Consistent with protein count
3	Protein heterocomplex	Heteromer	4 / 0 / 0 / 0	Consistent with protein count

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	1q9l
Deposition date deposition_date	2003-08-25
Structure title title	S25-2 Fab Unliganded 2
Keywords keywords	antigen-binding fragment, Fab, anti-carbohydrate, anti-LPS, antibody, immunoglobulin, IMMUNE SYSTEM; IMMUNE SYSTEM
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.

1q9l__assembly_3__model_1

Assembly 3 · Model 1 · CRYSOL 4.1.3-1-20251215 (887e7ef)

Download this curve (.dat)

1q9l__assembly_3__model_1 | I(q)

100 plotted points; both axes use logarithmic scales.

1q9l__assembly_3__model_1 | P(r) · Pending

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

Rg（Guinier）	39.62 Å
Rg (electron density)	39.94 Å
Total Rg	40.23 Å
Atom count	6808
Residues	882
Excluded volume	120300 Å³
Maximum q	0.500 Å⁻¹

Assembly	Model	Structure unit	Oligomeric description	Status	CRYSOL	Actions
1	1	`1q9l__assembly_1__model_1`	dimeric （2）	Success	4.1.3-1-20251215 (887e7ef)	View Download
2	1	`1q9l__assembly_2__model_1`	dimeric （2）	Success	4.1.3-1-20251215 (887e7ef)	View Download
3	1	`1q9l__assembly_3__model_1`	tetrameric （4）	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	S25-2 Fab (IgG1k) heavy chain
Molecular weight formula_weight	24111.0 kDa
Source method src_method	nat
Copy count entity_count	2

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	B,D
Atom count atom_count	7207

EVKLVESGGGLVQSGGSLRLSCATSGFTFTDYYMSWVRQPPGKALEWLGFIRNKANGYTTEYSPSVKGRFTISRDNSQSILYLQMNTLRAEDSATYYCARDHDGYYERFSYWGQGTLVTVSAAKTTPPSVYPLAPGSAAQTNSMVTLGCLVKGYFPEPVTVTWNSGSLSSGVHTFPAVLQSDLYTLSSSVTVPSSTWPSETVTCNVAHPASSTKVDKKIVPR

Entity 2 Entity 2 polymer

Description description	S25-2 Fab (IgG1k) light chain
Molecular weight formula_weight	24242.9 kDa
Source method src_method	nat
Copy count entity_count	2

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	A,C

DIVMSQSPSSLAVSAGEKVTMSCKSSQSLLNSRTRKNYLAWYQQKPGQSPKLLIYWASTRESGVPDRFTGSGSGTDFTLTITSVQAEDLAVYYCKQSYNLRTFGGGTKLEIKRADAAPTVSIFPPSSEQLTSGGASVVCFLNNFYPKDINVKWKIDGSERQNGVLNSWTDQDSKDSTYSMSSTLTLTKDEYERHNSYTCEATHKTSTSPIVKSFNRNEC

Entity 3 Entity 3 non-polymer

Description description	MAGNESIUM ION
Molecular weight formula_weight	24.3 kDa
Source method src_method	syn
Copy count entity_count	7

Entity 4 Entity 4 non-polymer

Description description	ZINC ION
Molecular weight formula_weight	65.4 kDa
Source method src_method	syn
Copy count entity_count	3

Entity 5 Entity 5 water

Description description	water
Molecular weight formula_weight	18.0 kDa
Source method src_method	nat
Copy count entity_count	399

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6. Fold Classification (SCOP + CATH) 16 domains

SCOP 2.08 (8 domains)

Domain ID domain_id	d1q9la1
Class class	b — All beta proteins
Fold Fold fold	b.1 — Immunoglobulin-like beta-sandwich
Superfamily Superfamily superfamily	b.1.1 — Immunoglobulin
Family Family family	b.1.1.1 — V set domains (antibody variable domain-like)

Domain ID domain_id	d1q9la2
Class class	b — All beta proteins
Fold Fold fold	b.1 — Immunoglobulin-like beta-sandwich
Superfamily Superfamily superfamily	b.1.1 — Immunoglobulin
Family Family family	b.1.1.2 — C1 set domains (antibody constant domain-like)

Domain ID domain_id	d1q9lb1
Class class	b — All beta proteins
Fold Fold fold	b.1 — Immunoglobulin-like beta-sandwich
Superfamily Superfamily superfamily	b.1.1 — Immunoglobulin
Family Family family	b.1.1.1 — V set domains (antibody variable domain-like)

Domain ID domain_id	d1q9lb2
Class class	b — All beta proteins
Fold Fold fold	b.1 — Immunoglobulin-like beta-sandwich
Superfamily Superfamily superfamily	b.1.1 — Immunoglobulin
Family Family family	b.1.1.2 — C1 set domains (antibody constant domain-like)

Domain ID domain_id	d1q9lc1
Class class	b — All beta proteins
Fold Fold fold	b.1 — Immunoglobulin-like beta-sandwich
Superfamily Superfamily superfamily	b.1.1 — Immunoglobulin
Family Family family	b.1.1.1 — V set domains (antibody variable domain-like)

Domain ID domain_id	d1q9lc2
Class class	b — All beta proteins
Fold Fold fold	b.1 — Immunoglobulin-like beta-sandwich
Superfamily Superfamily superfamily	b.1.1 — Immunoglobulin
Family Family family	b.1.1.2 — C1 set domains (antibody constant domain-like)

Domain ID domain_id	d1q9ld1
Class class	b — All beta proteins
Fold Fold fold	b.1 — Immunoglobulin-like beta-sandwich
Superfamily Superfamily superfamily	b.1.1 — Immunoglobulin
Family Family family	b.1.1.1 — V set domains (antibody variable domain-like)

Domain ID domain_id	d1q9ld2
Class class	b — All beta proteins
Fold Fold fold	b.1 — Immunoglobulin-like beta-sandwich
Superfamily Superfamily superfamily	b.1.1 — Immunoglobulin
Family Family family	b.1.1.2 — C1 set domains (antibody constant domain-like)

CATH v4.4 (8 domains)

Domain ID domain_id	1q9lA01
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	10 — Immunoglobulins

Domain ID domain_id	1q9lA02
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	10 — Immunoglobulins

Domain ID domain_id	1q9lB01
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	10 — Immunoglobulins

Domain ID domain_id	1q9lB02
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	10 — Immunoglobulins

Domain ID domain_id	1q9lC01
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	10 — Immunoglobulins

Domain ID domain_id	1q9lC02
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	10 — Immunoglobulins

Domain ID domain_id	1q9lD01
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	10 — Immunoglobulins

Domain ID domain_id	1q9lD02
Class class	2 — Mainly Beta
Architecture architecture	60 — Sandwich
Topology topology	40 — Immunoglobulin-like
Homologous superfamily homologous superfamily	10 — Immunoglobulins

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Unit-cell length a length_a	84.700 Å
Unit-cell length b length_b	96.000 Å
Unit-cell length c length_c	114.200 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	8

Space group space_group	P 21 21 21
Space-group number int_tables_number	19
Crystal system crystal_system	—

Resolution resolution	2.280 Å
Low-resolution limit resolution_low	19.850 Å
R factor r_factor	—
R_work r_work	0.2160
R_free r_free	0.2860

S25-2 Fab Unliganded 2

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

Assembly Composition of the Current Entry

2. Structure Basics 2. Structure Basics

3. Official assembly/model SAXS Official SAXS Profiles

1q9l__assembly_3__model_1

1q9l__assembly_3__model_1 | I(q)

1q9l__assembly_3__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

Entity 2 Entity 2 polymer

Polymer 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)