SAXSdb — 1f34

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

PEPSIN A

OrganismNot specified

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein heterocomplex	Heteromer	Protein 2	MAJOR PEPSIN INHIBITOR PI-3 × 1 （P19400） (4S)-2-METHYL-2,4-PENTANEDIOL × 1 water × 2	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	PEPA_PIG
Isoform	—
PDB entities	1
Chains and sequence ranges	Author chain A； PDBConstruct 1–326； UniProt 60–386

MAJOR PEPSIN INHIBITOR PI-3

Ascaris suum

UniProt P19400

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein heterocomplex	Heteromer	Protein 2	PEPSIN A × 1 （P00791） (4S)-2-METHYL-2,4-PENTANEDIOL × 1 water × 2	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	API3_ASCSU
Isoform	—
PDB entities	2
Chains and sequence ranges	Author chain B； PDBConstruct 1–149； UniProt 21–169

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	1f34
Deposition date deposition_date	2000-05-31
Structure title title	CRYSTAL STRUCTURE OF ASCARIS PEPSIN INHIBITOR-3 BOUND TO PORCINE PEPSIN
Keywords keywords	proteinase-inhibitor complex, 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.

1f34__assembly_1__model_1

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

Download this curve (.dat)

1f34__assembly_1__model_1 | I(q)

100 plotted points; both axes use logarithmic scales.

1f34__assembly_1__model_1 | P(r) · Pending

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

Rg（Guinier）	23.67 Å
Rg (electron density)	22.40 Å
Total Rg	23.37 Å
Atom count	3515
Residues	463
Excluded volume	62096 Å³
Maximum q	0.500 Å⁻¹

Assembly	Model	Structure unit	Oligomeric description	Status	CRYSOL	Actions
1	1	`1f34__assembly_1__model_1`	dimeric （2）	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	PEPSIN A
Molecular weight formula_weight	34593.5 kDa
EC 编号 ec_number	3.4.23.1
Source method src_method	nat
Copy count entity_count	1

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	A
Atom count atom_count	3617

IGDEPLENYLDTEYFGTIGIGTPAQDFTVIFDTGSSNLWVPSVYCSSLACSDHNQFNPDDSSTFEATSQELSITYGTGSMTGILGYDTVQVGGISDTNQIFGLSETEPGSFLYYAPFDGILGLAYPSISASGATPVFDNLWDQGLVSQDLFSVYLSSNDDSGSVVLLGGIDSSYYTGSLNWVPVSVEGYWQITLDSITMDGETIACSGGCQAIVDTGTSLLTGPTSAIANIQSDIGASENSDGEMVISCSSIDSLPDIVFTINGVQYPLSPSAYILQDDDSCTSGFEGMDVPTSSGELWILGDVFIRQYYTVFDRANNKVGLAPVA

Entity 2 Entity 2 polymer

Description description	MAJOR PEPSIN INHIBITOR PI-3
Molecular weight formula_weight	16411.7 kDa
Source method src_method	man
Copy count entity_count	1

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	B

QFLFSMSTGPFICTVKDNQVFVANLPWTMLEGDDIQVGKEFAARVEDCTNVKHDMAPTCTKPPPFCGPQDMKMFNFVGCSVLGNKLFIDQKYVRDLTAKDHAEVQTFREKIAAFEEQQENQPPSSGMPHGAVPAGGLSPPPPPSFCTVQ

Source Source

Source organism organism	Ascaris suum
Common name common_name	pig roundworm
NCBI taxonomy ID ncbi_taxonomy_id	6253
Host organism host_organism	Escherichia coli

Entity 3 Entity 3 non-polymer

Description description	(4S)-2-METHYL-2,4-PENTANEDIOL
Molecular weight formula_weight	118.2 kDa
Source method src_method	syn
Copy count entity_count	1

Entity 4 Entity 4 water

Description description	water
Molecular weight formula_weight	18.0 kDa
Source method src_method	nat
Copy count entity_count	102

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6. Fold Classification (SCOP + CATH) 6 domains

SCOP 2.08 (2 domains)

Domain ID domain_id	d1f34a_
Class class	b — All beta proteins
Fold Fold fold	b.50 — Acid proteases
Superfamily Superfamily superfamily	b.50.1 — Acid proteases
Family Family family	b.50.1.2 — Pepsin-like

Domain ID domain_id	d1f34b_
Class class	d — Alpha and beta proteins (a+b)
Fold Fold fold	d.62 — Pepsin inhibitor-3
Superfamily Superfamily superfamily	d.62.1 — Pepsin inhibitor-3
Family Family family	d.62.1.1 — Pepsin inhibitor-3

CATH v4.4 (4 domains)

Domain ID domain_id	1f34A01
Class class	2 — Mainly Beta
Architecture architecture	40 — Beta Barrel
Topology topology	70 — Cathepsin D, subunit A; domain 1
Homologous superfamily homologous superfamily	10 — Acid Proteases

Domain ID domain_id	1f34A02
Class class	2 — Mainly Beta
Architecture architecture	40 — Beta Barrel
Topology topology	70 — Cathepsin D, subunit A; domain 1
Homologous superfamily homologous superfamily	10 — Acid Proteases

Domain ID domain_id	1f34B01
Class class	3 — Alpha Beta
Architecture architecture	30 — 2-Layer Sandwich
Topology topology	1120 — Arylsulfatase, C-terminal domain
Homologous superfamily homologous superfamily	50 — Pepsin inhibitor-3

Domain ID domain_id	1f34B02
Class class	3 — Alpha Beta
Architecture architecture	30 — 2-Layer Sandwich
Topology topology	1120 — Arylsulfatase, C-terminal domain
Homologous superfamily homologous superfamily	50 — Pepsin inhibitor-3

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Unit-cell length a length_a	65.374 Å
Unit-cell length b length_b	97.593 Å
Unit-cell length c length_c	136.394 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	C 2 2 21
Space-group number int_tables_number	20
Crystal system crystal_system	—

Resolution resolution	2.450 Å
Low-resolution limit resolution_low	18.660 Å
R factor r_factor	0.2180
R_work r_work	0.2180
R_free r_free	0.2900

CRYSTAL STRUCTURE OF ASCARIS PEPSIN INHIBITOR-3 BOUND TO PORCINE PEPSIN

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

PEPSIN A

State in the Current Structure

Other States of the Same Protein in the Database

MAJOR PEPSIN INHIBITOR PI-3

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

1f34__assembly_1__model_1

1f34__assembly_1__model_1 | I(q)

1f34__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

Entity 2 Entity 2 polymer

Polymer Polymer

Source Source

Entity 3 Entity 3 non-polymer

Entity 4 Entity 4 water

6. Fold Classification (SCOP + CATH) 6 domains

SCOP 2.08 (2 domains)

CATH v4.4 (4 domains)

7. Citations (1)

CRYSTAL STRUCTURE OF ASCARIS PEPSIN INHIBITOR-3 BOUND TO PORCINE PEPSIN

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

PEPSIN 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

MAJOR PEPSIN INHIBITOR PI-3

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

1f34__assembly_1__model_1

1f34__assembly_1__model_1 | I(q)

1f34__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

Entity 2 Entity 2 polymer

Polymer Polymer

Source Source

Entity 3 Entity 3 non-polymer

Entity 4 Entity 4 water

6. Fold Classification (SCOP + CATH) 6 domains

SCOP 2.08 (2 domains)

CATH v4.4 (4 domains)

7. Citations (1)