3ru4

Crystal structure of the Bowman-Birk serine protease inhibitor BTCI in complex with trypsin and chymotrypsin

Method: X-RAY DIFFRACTION

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

Cationic trypsin

OrganismNot specified

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein heterocomplex	Heteromer	Protein 5	Bowman-Birk type seed trypsin and chymotrypsin inhibitor × 1 （P17734） Chymotrypsinogen A × 1 （P00766） Chymotrypsinogen A × 1 （P00766） Chymotrypsinogen A × 1 （P00766） CALCIUM ION × 1 GLYCEROL × 6 SULFATE ION × 9 1,2-ETHANEDIOL × 6 (4R)-2-METHYLPENTANE-2,4-DIOL × 2 water × 5	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	TRY1_BOVIN
Isoform	—
PDB entities	1
Chains and sequence ranges	Author chain T； PDBConstruct 1–223； UniProt 24–246

Bowman-Birk type seed trypsin and chymotrypsin inhibitor

OrganismNot specified

UniProt P17734

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein heterocomplex	Heteromer	Protein 5	Cationic trypsin × 1 （P00760） Chymotrypsinogen A × 1 （P00766） Chymotrypsinogen A × 1 （P00766） Chymotrypsinogen A × 1 （P00766） CALCIUM ION × 1 GLYCEROL × 6 SULFATE ION × 9 1,2-ETHANEDIOL × 6 (4R)-2-METHYLPENTANE-2,4-DIOL × 2 water × 5	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	IBB_VIGUN
Isoform	—
PDB entities	2
Chains and sequence ranges	Author chain B； PDBConstruct 1–61； UniProt 14–74

Chymotrypsinogen A

OrganismNot specified

UniProt P00766

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein heterocomplex	Heteromer	Protein 5	Cationic trypsin × 1 （P00760） Bowman-Birk type seed trypsin and chymotrypsin inhibitor × 1 （P17734） CALCIUM ION × 1 GLYCEROL × 6 SULFATE ION × 9 1,2-ETHANEDIOL × 6 (4R)-2-METHYLPENTANE-2,4-DIOL × 2 water × 5	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	CTRA_BOVIN
Isoform	—
PDB entities	3, 4, 5
Chains and sequence ranges	Author chain C； PDBConstruct 1–11； UniProt 1–11 Author chain D； PDBConstruct 1–131； UniProt 16–146 Author chain E； PDBConstruct 1–96； UniProt 150–245

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	3ru4
Deposition date deposition_date	2011-05-04
Structure title title	Crystal structure of the Bowman-Birk serine protease inhibitor BTCI in complex with trypsin and chymotrypsin
Keywords keywords	serine protease and bowman-birk fold, digestion and inhibition, HYDROLASE-HYDROLASE INHIBITOR complex; HYDROLASE/HYDROLASE INHIBITOR
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.

3ru4__assembly_1__model_1

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

Download this curve (.dat)

3ru4__assembly_1__model_1 | I(q)

100 plotted points; both axes use logarithmic scales.

3ru4__assembly_1__model_1 | P(r) · Pending

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

Rg（Guinier）	25.94 Å
Rg (electron density)	25.42 Å
Total Rg	26.11 Å
Atom count	3956
Residues	522
Excluded volume	70113 Å³
Maximum q	0.500 Å⁻¹

Assembly	Model	Structure unit	Oligomeric description	Status	CRYSOL	Actions
1	1	`3ru4__assembly_1__model_1`	pentameric （5）	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 (11)

Entity 1 Entity 1 polymer

Description description	Cationic trypsin
Molecular weight formula_weight	23324.3 kDa
EC 编号 ec_number	3.4.21.4
Source method src_method	nat
Copy count entity_count	1

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	T
Atom count atom_count	4732

IVGGYTCGANTVPYQVSLNSGYHFCGGSLINSQWVVSAAHCYKSGIQVRLGEDNINVVEGNEQFISASKSIVHPSYNSNTLNNDIMLIKLKSAASLNSRVASISLPTSCASAGTQCLISGWGNTKSSGTSYPDVLKCLKAPILSDSSCKSAYPGQITSNMFCAGYLEGGKDSCQGDSGGPVVCSGKLQGIVSWGSGCAQKNKPGVYTKVCNYVSWIKQTIASN

Entity 2 Entity 2 polymer

Description description	Bowman-Birk type seed trypsin and chymotrypsin inhibitor
Molecular weight formula_weight	6689.8 kDa
Source method src_method	nat
Copy count entity_count	1

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	B

SSKPCCDRCECTKSIPPQCRCSDVRLNSCHSACKSCACTFSIPAQCFCGDINDFCYKPCKS

Entity 3 Entity 3 polymer

Description description	Chymotrypsinogen A
Molecular weight formula_weight	1083.3 kDa
EC 编号 ec_number	3.4.21.1
Source method src_method	nat
Copy count entity_count	1

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	C

CGVPAIQPVLS

Entity 4 Entity 4 polymer

Description description	Chymotrypsinogen A
Molecular weight formula_weight	13934.6 kDa
EC 编号 ec_number	3.4.21.1
Source method src_method	nat
Copy count entity_count	1

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	D

IVNGEEAVPGSWPWQVSLQDKTGFHFCGGSLINENWVVTAAHCGVTTSDVVVAGEFDQGSSSEKIQKLKIAKVFKNSKYNSLTINNDITLLKLSTAASFSQTVSAVCLPSASDDFAAGTTCVTTGWGLTRY

Entity 5 Entity 5 polymer

Description description	Chymotrypsinogen A
Molecular weight formula_weight	10003.4 kDa
EC 编号 ec_number	3.4.21.1
Source method src_method	nat
Copy count entity_count	1

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	E

NTPDRLQQASLPLLSNTNCKKYWGTKIKDAMICAGASGVSSCMGDSGGPLVCKKNGAWTLVGIVSWGSSTCSTSTPGVYARVTALVNWVQQTLAAN

Entity 6 Entity 6 non-polymer

Description description	CALCIUM ION
Molecular weight formula_weight	40.1 kDa
Source method src_method	syn
Copy count entity_count	1

Entity 7 Entity 7 non-polymer

Description description	GLYCEROL
Molecular weight formula_weight	92.1 kDa
Source method src_method	syn
Copy count entity_count	6

Entity 8 Entity 8 non-polymer

Description description	SULFATE ION
Molecular weight formula_weight	96.1 kDa
Source method src_method	syn
Copy count entity_count	9

Entity 9 Entity 9 non-polymer

Description description	1,2-ETHANEDIOL
Molecular weight formula_weight	62.1 kDa
Source method src_method	syn
Copy count entity_count	6

Entity 10 Entity 10 non-polymer

Description description	(4R)-2-METHYLPENTANE-2,4-DIOL
Molecular weight formula_weight	118.2 kDa
Source method src_method	syn
Copy count entity_count	2

Entity 11 Entity 11 water

Description description	water
Molecular weight formula_weight	18.0 kDa
Source method src_method	nat
Copy count entity_count	694

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6. Fold Classification (SCOP + CATH) 7 domains

SCOP 2.08 (2 domains)

Domain ID domain_id	d3ru4b_
Class class	g — Small proteins
Fold Fold fold	g.3 — Knottins (small inhibitors, toxins, lectins)
Superfamily Superfamily superfamily	g.3.13 — Bowman-Birk inhibitor, BBI
Family Family family	g.3.13.1 — Bowman-Birk inhibitor, BBI

Domain ID domain_id	d3ru4t_
Class class	b — All beta proteins
Fold Fold fold	b.47 — Trypsin-like serine proteases
Superfamily Superfamily superfamily	b.47.1 — Trypsin-like serine proteases
Family Family family	b.47.1.2 — Eukaryotic proteases

CATH v4.4 (5 domains)

Domain ID domain_id	3ru4B00
Class class	2 — Mainly Beta
Architecture architecture	10 — Ribbon
Topology topology	69 — Cysteine Protease (Bromelain) Inhibitor, subunit H
Homologous superfamily homologous superfamily	10 — Cysteine Protease (Bromelain) Inhibitor, subunit H

Domain ID domain_id	3ru4D00
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	3ru4E00
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	3ru4T01
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	3ru4T02
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

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Unit-cell length a length_a	49.477 Å
Unit-cell length b length_b	54.571 Å
Unit-cell length c length_c	69.286 Å
Unit-cell angle α angle_alpha	67.28 °
Unit-cell angle β angle_beta	71.04 °
Unit-cell angle γ angle_gamma	73.55 °
Molecules per unit cell Z z_pdb	1

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

Resolution resolution	1.680 Å
Low-resolution limit resolution_low	62.020 Å
R factor r_factor	0.1590
R_work r_work	0.1572
R_free r_free	0.1925

Crystal structure of the Bowman-Birk serine protease inhibitor BTCI in complex with trypsin and chymotrypsin

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

Cationic trypsin

State in the Current Structure

Other States of the Same Protein in the Database

Monomer

Homodimer

Homotetramer

Other homooligomers

Heteromeric or nucleic-acid complex

Bowman-Birk type seed trypsin and chymotrypsin inhibitor

State in the Current Structure

Other States of the Same Protein in the Database

Monomer

Homodimer

Homotetramer

Other homooligomers

Heteromeric or nucleic-acid complex

Chymotrypsinogen A

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

3ru4__assembly_1__model_1

3ru4__assembly_1__model_1 | I(q)

3ru4__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 (11)

Entity 1 Entity 1 polymer

Polymer Polymer

Entity 2 Entity 2 polymer

Polymer Polymer

Entity 3 Entity 3 polymer

Polymer Polymer

Entity 4 Entity 4 polymer

Polymer Polymer

Entity 5 Entity 5 polymer

Polymer Polymer

Entity 6 Entity 6 non-polymer

Entity 7 Entity 7 non-polymer

Entity 8 Entity 8 non-polymer

Entity 9 Entity 9 non-polymer

Entity 10 Entity 10 non-polymer

Entity 11 Entity 11 water

6. Fold Classification (SCOP + CATH) 7 domains

SCOP 2.08 (2 domains)

CATH v4.4 (5 domains)

7. Citations (2)