1l2a

The Crystal Structure and Catalytic Mechanism of Cellobiohydrolase CelS, the Major Enzymatic Component of the Clostridium thermocellum cellulosome

Method: X-RAY DIFFRACTION

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

cellobiohydrolase

Clostridium thermocellum

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Other combination	Monomer	Protein 1 其他Polymer 2	beta-D-glucopyranose-(1-4)-beta-D-glucopyranose × 1 ;beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose ; × 1 water × 1	Consistent with protein count
2	Other combination	Monomer	Protein 1 其他Polymer 2	beta-D-glucopyranose-(1-4)-beta-D-glucopyranose × 1 ;beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose ; × 1 water × 1	Consistent with protein count
3	Other combination	Monomer	Protein 1 其他Polymer 2	beta-D-glucopyranose-(1-4)-beta-D-glucopyranose × 1 ;beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose ; × 1 water × 1	Consistent with protein count
4	Other combination	Monomer	Protein 1 其他Polymer 2	beta-D-glucopyranose-(1-4)-beta-D-glucopyranose × 1 ;beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose ; × 1 water × 1	Consistent with protein count
5	Other combination	Monomer	Protein 1 其他Polymer 2	beta-D-glucopyranose-(1-4)-beta-D-glucopyranose × 1 ;beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose ; × 1 water × 1	Consistent with protein count
6	Other combination	Monomer	Protein 1 其他Polymer 2	beta-D-glucopyranose-(1-4)-beta-D-glucopyranose × 1 ;beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose ; × 1 water × 1	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	GUNS_CLOTM
Isoform	—
PDB entities	1
Chains and sequence ranges	Author chain A； PDBConstruct 1–678； UniProt 1–678 Author chain B； PDBConstruct 1–678； UniProt 1–678 Author chain C； PDBConstruct 1–678； UniProt 1–678 Author chain D； PDBConstruct 1–678； UniProt 1–678 Author chain E； PDBConstruct 1–678； UniProt 1–678 Author chain F； PDBConstruct 1–678； UniProt 1–678

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	1l2a
Deposition date deposition_date	2002-02-20
Structure title title	The Crystal Structure and Catalytic Mechanism of Cellobiohydrolase CelS, the Major Enzymatic Component of the Clostridium thermocellum cellulosome
Keywords keywords	alpha/alpha barrel, 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.

1l2a__assembly_1__model_1

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

Download this curve (.dat)

1l2a__assembly_1__model_1 | I(q)

100 plotted points; both axes use logarithmic scales.

1l2a__assembly_1__model_1 | P(r) · Pending

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

Rg（Guinier）	24.51 Å
Rg (electron density)	23.30 Å
Total Rg	24.24 Å
Atom count	5192
Residues	642
Excluded volume	91229 Å³
Maximum q	0.500 Å⁻¹

Assembly	Model	Structure unit	Oligomeric description	Status	CRYSOL	Actions
1	1	`1l2a__assembly_1__model_1`	monomeric （1）	Success	4.1.3-1-20251215 (887e7ef)	View Download
2	1	`1l2a__assembly_2__model_1`	monomeric （1）	Success	4.1.3-1-20251215 (887e7ef)	View Download
3	1	`1l2a__assembly_3__model_1`	monomeric （1）	Success	4.1.3-1-20251215 (887e7ef)	View Download
4	1	`1l2a__assembly_4__model_1`	monomeric （1）	Success	4.1.3-1-20251215 (887e7ef)	View Download
5	1	`1l2a__assembly_5__model_1`	monomeric （1）	Success	4.1.3-1-20251215 (887e7ef)	View Download
6	1	`1l2a__assembly_6__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 (4)

Entity 1 Entity 1 polymer

Description description	cellobiohydrolase
Molecular weight formula_weight	76638.3 kDa
EC 编号 ec_number	3.2.1.4
Source method src_method	man
Copy count entity_count	6

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	A,B,C,D,E,F
Atom count atom_count	32414

MVKSRKISILLAVAMLVSIMIPTTAFAGPTKAPTKDGTSYKDLFLELYGKIKDPKNGYFSPDEGIPYHSIETLIVEAPDYGHVTTSEAFSYYVWLEAMYGNLTGNWSGVETAWKVMEDWIIPDSTEQPGMSSYNPNSPATYADEYEDPSYYPSELKFDTVRVGSDPVHNDLVSAYGPNMYLMHWLMDVDNWYGFGTGTRATFINTFQRGEQESTWETIPHPSIEEFKYGGPNGFLDLFTKDRSYAKQWRYTNAPDAEGRAIQAVYWANKWAKEQGKGSAVASVVSKAAKMGDFLRNDMFDKYFMKIGAQDKTPATGYDSAHYLMAWYTAWGGGIGASWAWKIGCSHAHFGYQNPFQGWVSATQSDFAPKSSNGKRDWTTSYKRQLEFYQWLQSAEGGIAGGATNSWNGRYEKYPAGTSTFYGMAYVPHPVYADPGSNQWFGFQAWSMQRVMEYYLETGDSSVKNLIKKWVDWVMSEIKLYDDGTFAIPSDLEWSGQPDTWTGTYTGNPNLHVRVTSYGTDLGVAGSLANALATYAAATERWEGKLDTKARDMAAELVNRAWYNFYCSEGKGVVTEEARADYKRFFEQEVYVPAGWSGTMPNGDKIQPGIKFIDIRTKYRQDPYYDIVYQAYLRGEAPVLNYHRFWHEVDLAVAMGVLATYFPDMTYKVPGTPSTKLYG

Source Source

Source organism organism	Clostridium thermocellum
NCBI taxonomy ID ncbi_taxonomy_id	1515
Host organism host_organism	Escherichia coli

Entity 2 Entity 2 branched

Description description	beta-D-glucopyranose-(1-4)-beta-D-glucopyranose
Molecular weight formula_weight	342.3 kDa
Source method src_method	man
Copy count entity_count	6

Entity 3 Entity 3 branched

Description description	;beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose ;
Molecular weight formula_weight	990.9 kDa
Source method src_method	man
Copy count entity_count	6

Entity 4 Entity 4 water

Description description	water
Molecular weight formula_weight	18.0 kDa
Source method src_method	nat
Copy count entity_count	1150

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6. Fold Classification (SCOP + CATH) 24 domains

SCOP 2.08 (6 domains)

Domain ID domain_id	d1l2aa_
Class class	a — All alpha proteins
Fold Fold fold	a.102 — alpha/alpha toroid
Superfamily Superfamily superfamily	a.102.1 — Six-hairpin glycosidases
Family Family family	a.102.1.2 — Cellulases catalytic domain

Domain ID domain_id	d1l2ab_
Class class	a — All alpha proteins
Fold Fold fold	a.102 — alpha/alpha toroid
Superfamily Superfamily superfamily	a.102.1 — Six-hairpin glycosidases
Family Family family	a.102.1.2 — Cellulases catalytic domain

Domain ID domain_id	d1l2ac_
Class class	a — All alpha proteins
Fold Fold fold	a.102 — alpha/alpha toroid
Superfamily Superfamily superfamily	a.102.1 — Six-hairpin glycosidases
Family Family family	a.102.1.2 — Cellulases catalytic domain

Domain ID domain_id	d1l2ad_
Class class	a — All alpha proteins
Fold Fold fold	a.102 — alpha/alpha toroid
Superfamily Superfamily superfamily	a.102.1 — Six-hairpin glycosidases
Family Family family	a.102.1.2 — Cellulases catalytic domain

Domain ID domain_id	d1l2ae_
Class class	a — All alpha proteins
Fold Fold fold	a.102 — alpha/alpha toroid
Superfamily Superfamily superfamily	a.102.1 — Six-hairpin glycosidases
Family Family family	a.102.1.2 — Cellulases catalytic domain

Domain ID domain_id	d1l2af_
Class class	a — All alpha proteins
Fold Fold fold	a.102 — alpha/alpha toroid
Superfamily Superfamily superfamily	a.102.1 — Six-hairpin glycosidases
Family Family family	a.102.1.2 — Cellulases catalytic domain

CATH v4.4 (18 domains)

Domain ID domain_id	1l2aA01
Class class	1 — Mainly Alpha
Architecture architecture	50 — Alpha/alpha barrel
Topology topology	10 — Glycosyltransferase
Homologous superfamily homologous superfamily	10 —

Domain ID domain_id	1l2aA02
Class class	2 — Mainly Beta
Architecture architecture	170 — Beta Complex
Topology topology	160 — Endo-1,4-beta-glucanase f; domain 2
Homologous superfamily homologous superfamily	10 — Endo-1,4-beta-glucanase f. Domain 2

Domain ID domain_id	1l2aA03
Class class	4 — Few Secondary Structures
Architecture architecture	10 — Irregular
Topology topology	870 — Endo-1,4-beta-glucanase f; domain 3
Homologous superfamily homologous superfamily	10 — Endo-1,4-beta-glucanase f. Domain 3

Domain ID domain_id	1l2aB01
Class class	1 — Mainly Alpha
Architecture architecture	50 — Alpha/alpha barrel
Topology topology	10 — Glycosyltransferase
Homologous superfamily homologous superfamily	10 —

Domain ID domain_id	1l2aB02
Class class	2 — Mainly Beta
Architecture architecture	170 — Beta Complex
Topology topology	160 — Endo-1,4-beta-glucanase f; domain 2
Homologous superfamily homologous superfamily	10 — Endo-1,4-beta-glucanase f. Domain 2

Domain ID domain_id	1l2aB03
Class class	4 — Few Secondary Structures
Architecture architecture	10 — Irregular
Topology topology	870 — Endo-1,4-beta-glucanase f; domain 3
Homologous superfamily homologous superfamily	10 — Endo-1,4-beta-glucanase f. Domain 3

Domain ID domain_id	1l2aC01
Class class	1 — Mainly Alpha
Architecture architecture	50 — Alpha/alpha barrel
Topology topology	10 — Glycosyltransferase
Homologous superfamily homologous superfamily	10 —

Domain ID domain_id	1l2aC02
Class class	2 — Mainly Beta
Architecture architecture	170 — Beta Complex
Topology topology	160 — Endo-1,4-beta-glucanase f; domain 2
Homologous superfamily homologous superfamily	10 — Endo-1,4-beta-glucanase f. Domain 2

Domain ID domain_id	1l2aC03
Class class	4 — Few Secondary Structures
Architecture architecture	10 — Irregular
Topology topology	870 — Endo-1,4-beta-glucanase f; domain 3
Homologous superfamily homologous superfamily	10 — Endo-1,4-beta-glucanase f. Domain 3

Domain ID domain_id	1l2aD01
Class class	1 — Mainly Alpha
Architecture architecture	50 — Alpha/alpha barrel
Topology topology	10 — Glycosyltransferase
Homologous superfamily homologous superfamily	10 —

Domain ID domain_id	1l2aD02
Class class	2 — Mainly Beta
Architecture architecture	170 — Beta Complex
Topology topology	160 — Endo-1,4-beta-glucanase f; domain 2
Homologous superfamily homologous superfamily	10 — Endo-1,4-beta-glucanase f. Domain 2

Domain ID domain_id	1l2aD03
Class class	4 — Few Secondary Structures
Architecture architecture	10 — Irregular
Topology topology	870 — Endo-1,4-beta-glucanase f; domain 3
Homologous superfamily homologous superfamily	10 — Endo-1,4-beta-glucanase f. Domain 3

Domain ID domain_id	1l2aE01
Class class	1 — Mainly Alpha
Architecture architecture	50 — Alpha/alpha barrel
Topology topology	10 — Glycosyltransferase
Homologous superfamily homologous superfamily	10 —

Domain ID domain_id	1l2aE02
Class class	2 — Mainly Beta
Architecture architecture	170 — Beta Complex
Topology topology	160 — Endo-1,4-beta-glucanase f; domain 2
Homologous superfamily homologous superfamily	10 — Endo-1,4-beta-glucanase f. Domain 2

Domain ID domain_id	1l2aE03
Class class	4 — Few Secondary Structures
Architecture architecture	10 — Irregular
Topology topology	870 — Endo-1,4-beta-glucanase f; domain 3
Homologous superfamily homologous superfamily	10 — Endo-1,4-beta-glucanase f. Domain 3

Domain ID domain_id	1l2aF01
Class class	1 — Mainly Alpha
Architecture architecture	50 — Alpha/alpha barrel
Topology topology	10 — Glycosyltransferase
Homologous superfamily homologous superfamily	10 —

Domain ID domain_id	1l2aF02
Class class	2 — Mainly Beta
Architecture architecture	170 — Beta Complex
Topology topology	160 — Endo-1,4-beta-glucanase f; domain 2
Homologous superfamily homologous superfamily	10 — Endo-1,4-beta-glucanase f. Domain 2

Domain ID domain_id	1l2aF03
Class class	4 — Few Secondary Structures
Architecture architecture	10 — Irregular
Topology topology	870 — Endo-1,4-beta-glucanase f; domain 3
Homologous superfamily homologous superfamily	10 — Endo-1,4-beta-glucanase f. Domain 3

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Unit-cell length a length_a	148.027 Å
Unit-cell length b length_b	207.640 Å
Unit-cell length c length_c	215.354 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	24

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

Resolution resolution	2.500 Å
Low-resolution limit resolution_low	15.000 Å
R factor r_factor	0.1831
R_work r_work	0.1809
R_free r_free	0.2258

The Crystal Structure and Catalytic Mechanism of Cellobiohydrolase CelS, the Major Enzymatic Component of the Clostridium thermocellum cellulosome

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

cellobiohydrolase

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

1l2a__assembly_1__model_1

1l2a__assembly_1__model_1 | I(q)

1l2a__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 (4)

Entity 1 Entity 1 polymer

Polymer Polymer

Source Source

Entity 2 Entity 2 branched

Entity 3 Entity 3 branched

Entity 4 Entity 4 water

6. Fold Classification (SCOP + CATH) 24 domains

SCOP 2.08 (6 domains)

CATH v4.4 (18 domains)

7. Citations (1)

The Crystal Structure and Catalytic Mechanism of Cellobiohydrolase CelS, the Major Enzymatic Component of the Clostridium thermocellum cellulosome

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

cellobiohydrolase

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

1l2a__assembly_1__model_1

1l2a__assembly_1__model_1 | I(q)

1l2a__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 (4)

Entity 1 Entity 1 polymer

Polymer Polymer

Source Source

Entity 2 Entity 2 branched

Entity 3 Entity 3 branched

Entity 4 Entity 4 water

6. Fold Classification (SCOP + CATH) 24 domains

SCOP 2.08 (6 domains)

CATH v4.4 (18 domains)

7. Citations (1)