DB code: S00295

RLCP classification	1.13.30000.9 : Hydrolysis
CATH domain	3.40.50.200 : Rossmann fold	Catalytic domain
E.C.	3.4.21.64
CSA
M-CSA
MACiE

CATH domain	Related DB codes (homologues)
3.40.50.200 : Rossmann fold	S00296 D00219 S00519

Uniprot Enzyme Name
UniprotKB	Protein name	Synonyms	MEROPS	Pfam
P06873	Proteinase K	EC 3.4.21.64 Tritirachium alkaline proteinase Endopeptidase K	S08.054 (Serine)	PF05922 (Inhibitor_I9) PF00082 (Peptidase_S8) [Graphical View]

KEGG enzyme name
peptidase K Tritirachium alkaline proteinase Tritirachium album serine proteinase proteinase K Tritirachium album proteinase K endopeptidase K

UniprotKB: Accession Number	Entry name	Activity	Subunit	Subcellular location	Cofactor
P06873	PRTK_TRIAL	Hydrolysis of keratin, and of other proteins with subtilisin-like specificity. Hydrolyzes peptide amides.			Binds 2 calcium ions per subunit.

KEGG Pathways
Map code	Pathways	E.C.

Compound table
	Substrates			Products		Intermediates
KEGG-id	C00017	C00012	C00001	C00017	C00012	I00087	I00085	I00086
E.C.
Compound	Protein	Peptide	H2O	Protein	Peptide	Peptidyl-tetrahedral intermediate	Acyl-enzyme	Tetrahedral intermediate
Type	peptide/protein	peptide/protein	H2O	peptide/protein	peptide/protein
ChEBI			15377 15377
PubChem			22247451 962 22247451 962

1bjrE	Unbound	Bound:VAL-ALA-GLN-GLY-GLY-ALA-ALA-GLY-LEU-ALA		Unbound	Unbound	Unbound	Unbound	Unbound
1egqA	Unbound	Unbound		Unbound	Unbound	Unbound	Unbound	Unbound
1ic6A	Unbound	Unbound		Unbound	Unbound	Unbound	Unbound	Unbound
1pekE	Unbound	Unbound		Bound:PRO-ALA-PRO-PHE (chain C)	Bound:ALA-ALA (chain D)	Unbound	Unbound	Unbound
1ptkA	Unbound	Unbound		Unbound	Unbound	Unbound	Unbound	Unbound
2pkcA	Unbound	Unbound		Unbound	Unbound	Unbound	Unbound	Unbound
2prkA	Unbound	Unbound		Unbound	Unbound	Unbound	Unbound	Unbound
3prkE	Unbound	Unbound		Unbound	Unbound	Unbound	Unbound	Transition-state-analogue:MSU-ALA-ALA-PRO-ALA-CH2

Reference for Active-site residues
resource	references	E.C.
Swiss-prot;P06873 & PDB;1pek, 1ptk

Active-site residues
PDB	Catalytic residues	Cofactor-binding residues	Modified residues	Main-chain involved in catalysis	Comment

1bjrE	ASP 39;HIS 69;ASN 161;THR 223;SER 224			SER 224
1egqA	ASP 39;HIS 69;ASN 161;THR 223;SER 224			SER 224
1ic6A	ASP 39;HIS 69;ASN 161;THR 223;SER 224			SER 224
1pekE	ASP 39;HIS 69;ASN 161;THR 223;SER 224			SER 224
1ptkA	ASP 39;HIS 69;ASN 161;THR 223;SER 224			SER 224
2pkcA	ASP 39;HIS 69;ASN 161;THR 223;SER 224			SER 224
2prkA	ASP 39;HIS 69;ASN 161;THR 223;SER 224			SER 224
3prkE	ASP 39;HIS 69;ASN 161;THR 223;SER 224			SER 224

References for Catalytic Mechanism
References	Sections	No. of steps in catalysis
[3]	Fig.8, p.164-168	3

References
[1]
Resource
Comments	X-ray crystallography
Medline ID	84261419
PubMed ID	6378621
Journal	EMBO J
Year	1984
Volume	3
Pages	1311-4
Authors	Paehler A, Banerjee A, Dattagupta JK, Fujiwara T, Lindner K, Pal GP, Suck D, Weber G, Saenger W
Title	Three-dimensional structure of fungal proteinase K reveals similarity to bacterial subtilisin.
Related PDB
Related UniProtKB	P06873
[2]
Resource
Comments	X-ray crystallography (1.5 Angstroms)
Medline ID
PubMed ID	3271105
Journal	Acta Crystallogr B
Year	1988
Volume	44
Pages	163-72
Authors	Betzel C, Pal GP, Saenger W
Title	Synchrotron X-ray data collection and restrained least-squares refinement of the crystal structure of proteinase K at 1.5 A resolution.
Related PDB	2prk
Related UniProtKB
[3]
Resource
Comments	X-ray crystallography (1.5 Angstroms)
Medline ID
PubMed ID	3203685
Journal	Eur J Biochem
Year	1988
Volume	178
Pages	155-71
Authors	Betzel C, Pal GP, Saenger W
Title	Three-dimensional structure of proteinase K at 0.15-nm resolution.
Related PDB	1ptk
Related UniProtKB
[4]
Resource
Comments	X-ray crystallography (2.2 Angstroms)
Medline ID
PubMed ID	1894649
Journal	J Biol Chem
Year	1991
Volume	266
Pages	17695-9
Authors	Wolf WM, Bajorath J, Muller A, Raghunathan S, Singh TP, Hinrichs W, Saenger W
Title	Inhibition of proteinase K by methoxysuccinyl-Ala-Ala-Pro-Ala-chloromethyl ketone. An x-ray study at 2.2-A resolution.
Related PDB	3prkE
Related UniProtKB
[5]
Resource
Comments	X-ray crystallography (2.2 Angstroms)
Medline ID
PubMed ID	8340410
Journal	J Biol Chem
Year	1993
Volume	268
Pages	15854-8
Authors	Betzel C, Singh TP, Visanji M, Peters K, Fittkau S, Saenger W, Wilson KS
Title	Structure of the complex of proteinase K with a substrate analogue hexapeptide inhibitor at 2.2-A resolution.
Related PDB	1pekE
Related UniProtKB
[6]
Resource
Comments	X-ray crystallography (1.5 Angstroms)
Medline ID
PubMed ID	8083213
Journal	J Biol Chem
Year	1994
Volume	269
Pages	23108-11
Authors	Muller A, Hinrichs W, Wolf WM, Saenger W
Title	Crystal structure of calcium-free proteinase K at 1.5-A resolution.
Related PDB	2pkc
Related UniProtKB	P06873
[7]
Resource
Comments	X-ray crystallography (2.44 Angstroms)
Medline ID	98412873
PubMed ID	9741842
Journal	Proteins
Year	1998
Volume	33
Pages	30-8
Authors	Singh TP, Sharma S, Karthikeyan S, Betzel C, Bhatia KL
Title	Crystal structure of a complex formed between proteolytically-generated lactoferrin fragment and proteinase K.
Related PDB	1bjrE
Related UniProtKB	P06873
[8]
Resource
Comments	X-ray crystallography (2.2 Angstroms)
Medline ID
PubMed ID	10737944
Journal	Proteins
Year	2000
Volume	39
Pages	226-34
Authors	Gupta MN, Tyagi R, Sharma S, Karthikeyan S, Singh TP
Title	Enhancement of catalytic efficiency of enzymes through exposure to anhydrous organic solvent at 70 degrees C. Three-dimensional structure of a treated serine proteinase at 2.2 A resolution.
Related PDB	1cnm
Related UniProtKB
[9]
Resource
Comments	X-ray crystallography (0.98 Angstroms)
Medline ID
PubMed ID	11258922
Journal	Biochemistry
Year	2001
Volume	40
Pages	3080-8
Authors	Betzel C, Gourinath S, Kumar P, Kaur P, Perbandt M, Eschenburg S, Singh TP
Title	Structure of a serine protease proteinase K from Tritirachium album limber at 0.98 A resolution.
Related PDB	1ic6A
Related UniProtKB
[10]
Resource
Comments	X-ray crystallography, catalysis
Medline ID
PubMed ID	11563328
Journal	Indian J Biochem Biophys
Year	2001
Volume	38
Pages	34-41
Authors	Sharma S, Tyagi R, Gupta MN, Singh TP
Title	Enhancement of catalytic activity of enzymes by heating in anhydrous organic solvents: 3D structure of a modified serine proteinase at high resolution.
Related PDB
Related UniProtKB
[11]
Resource
Comments	X-ray crystallography (1.5 Angstroms)
Medline ID
PubMed ID	11438752
Journal	Protein Eng
Year	2001
Volume	14
Pages	307-13
Authors	Singh RK, Gourinath S, Sharma S, Roy I, Gupta MN, Betzel C, Srinivasan A, Singh TP
Title	Enhancement of enzyme activity through three-phase partitioning: crystal structure of a modified serine proteinase at 1.5 A resolution.
Related PDB	1egq
Related UniProtKB

Comments
This enzyme belongs to the peptidase family-S8. This enzyme, protenase K, also has a catalytic triad (Asp/His/Ser), which is the same as those of other serine proteases, such as chymotrypsin, trypsin and subtilisin. The paper [3] proposed a possible catalytic mechanism for this proteinase K, as follows: In the catalytic center, the oxyanion hole is occupied by a water molecule, and the substrate-recognition site is close to the center. A substrate peptide enters the active site, is attacked by the sidechain of Ser224 and the negative charge of the resulting tetrahedral hemiketal transition sate is stabilized by hydrogen-bond formation in the oxyanion hole. The leaving group of R-NH2 (product 1) leaves the active site and the acyl-enzyme formed is hydrolysed by a water molecule. The product-2 formed diffuses out of the substrate-recognition site and the oxyanion hole is filled by another water molecule [3]. However, in contrast to other trypsin-like serine proteases, the oxyanion hole is composed of sidechains of Asn161 and Thr223, as well as mainchain amide of Ser224, as in subtilisin (D00219 in EzCatDB).

Comments

This enzyme belongs to the peptidase family-S8.
This enzyme, protenase K, also has a catalytic triad (Asp/His/Ser), which is the same as those of other serine proteases, such as chymotrypsin, trypsin and subtilisin.
The paper [3] proposed a possible catalytic mechanism for this proteinase K, as follows:
In the catalytic center, the oxyanion hole is occupied by a water molecule, and the substrate-recognition site is close to the center. A substrate peptide enters the active site, is attacked by the sidechain of Ser224 and the negative charge of the resulting tetrahedral hemiketal transition sate is stabilized by hydrogen-bond formation in the oxyanion hole. The leaving group of R-NH2 (product 1) leaves the active site and the acyl-enzyme formed is hydrolysed by a water molecule. The product-2 formed diffuses out of the substrate-recognition site and the oxyanion hole is filled by another water molecule [3].
However, in contrast to other trypsin-like serine proteases, the oxyanion hole is composed of sidechains of Asn161 and Thr223, as well as mainchain amide of Ser224, as in subtilisin (D00219 in EzCatDB).

Created	Updated
2002-07-01	2011-02-21