9YBA: SFTI-1 containing L-2-Selenaproline at residue 8

SFTI-1 containing L-2-Selenaproline at residue 8 in complex with Trypsin. Determined by X-ray diffraction at 1.17 Å resolution. Released 23 Sept 2026.

Method: X-ray diffraction
Resolution: 1.17 Å
Organisms: Bos taurus, Helianthus annuus
Chains: 2
Atoms: 2,258
Mol. weight: 28.07 kDa
Ligands: CA
Released: 23 Sept 2026

Explore 9YBA in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

9YBA contains 8 α-helices and 20 β-strands across 2 chains. Residue ranges use author residue numbering, as in the PDB file, from PDBe. To see them in 3D, choose the Cartoon representation with Secondary structure coloring: helices, sheets and coils get different colors.

Chain A: 7 helices, 18 β-strands

Element	Residues	Length	Sheet
β-strand	25	1	1
β-strand	28-29	2	2
β-strand	38-42	5	3
β-strand	46-54	9	3
β-strand	57-60	4	3
α-helix	62-64	3
β-strand	70-73	4	3
β-strand	86-95	10	3
β-strand	109-113	5	3
β-strand	120	1	4
β-strand	123	1	4
β-strand	127	1	2
α-helix	128-129	2
α-helix	132-134	3
β-strand	138-143	6	2
β-strand	159-165	7	2
α-helix	166-167	2
α-helix	168-174	7
β-strand	183-186	4	2
β-strand	194	1	1
β-strand	203-206	4	2
β-strand	209-218	10	2
β-strand	227-231	5	2
α-helix	232-235	4
α-helix	236-244	9

Chain B: 1 helix, 2 β-strands

Element	Residues	Length	Sheet
β-strand	2-4	3	2
α-helix	9-10	2
β-strand	11	1	2

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Pretrypsinogen I,	A	protein	246	Bos taurus	P00760 (AlphaFold model)
Trypsin inhibitor 1	B	protein	14	Helianthus annuus	Q4GWU5 (AlphaFold model)

Sequence of entity 1 (A), FASTA

>9YBA_1 Pretrypsinogen I, (chains A)
MKTFIFLALLGAAVAFPVDDDDKIVGGYTCGANTVPYQVSLNSGYHFCGGSLINSQWVVS
AAHCYKSGIQVRLGEDNINVVEGNEQFISASKSIVHPSYNSNTLNNDIMLIKLKSAASLN
SRVASISLPTSCASAGTQCLISGWGNTKSSGTSYPDVLKCLKAPILSDSSCKSAYPGQIT
SNMFCAGYLEGGKDSCQGDSGGPVVCSGKLQGIVSWGSGCAQKNKPGVYTKVCNYVSWIK
QTIASN

Sequence of entity 2 (B), FASTA

>9YBA_2 Trypsin inhibitor 1 (chains B)
GRCTKSIXPICFPD

Ligands and cofactors

ID	Name	Formula	Copies
CA	Calcium ion	Ca	1

Water and common crystallization additives (SO4, GOL, EDO) are not listed.

Primary citation

SFTI-1 containing L-2-Selenaproline at residue 8 in complex with Trypsin. Gare, C.L., Frkic, R.L., White, A.M. et al. To be published.

Other PDB entries of the same protein (UniProt P00760 (AlphaFold model), which also has an AlphaFold model), best resolution first:

4I8H 0.75 Å, Bovine trypsin at 0.75 resolution
5MN1 0.79 Å, Cationic trypsin in complex with 2-aminopyridine (deuterated sample at 100 K)
5MNK 0.8 Å, Cationic trypsin in complex with benzylamine (deuterated sample at 100 K)
3MFJ 0.8 Å, Bovine trypsin at 0.8 A resolution, restrained refinement
3MI4 0.8 Å, Bovine trypsin at 0.8 A resolution, non-restrained refinement
4I8G 0.8 Å, Bovine trypsin at 0.8 resolution
4I8K 0.85 Å, Bovine trypsin at 0.85 resolution
5MNN 0.86 Å, Cationic trypsin in complex with N-amidinopiperidine (deuterated sample at 100 K)
5MNG 0.86 Å, Cationic trypsin in complex with benzamidine (deuterated sample at 100 K)
4I8J 0.87 Å, Bovine trypsin at 0.87 A resolution
4I8L 0.87 Å, Bovine trypsin at 0.87 resolution
4XOJ 0.91 Å, Structure of bovine trypsin in complex with analogues of sunflower inhibitor 1 (SFTI-1)

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