IUBMB Enzyme Nomenclature


Accepted name: HycI peptidase

Reaction: This enzyme specifically removes a 32-amino acid peptide from the C-terminus of the precursor of the large subunit of hydrogenase 3 in Escherichia coli by cleavage at the C-terminal side of Arg537.

Other name(s): HycI; HycE processing protein

Comments: The reaction requires nickel to be bound to the precursor of the large subunit of hydrogenase 3. The endopeptidase uses the metal in the large subunit of [NiFe]-hydrogenases as a recognition motif [1]. In peptidase family A31.

Links to other databases: BRENDA, EXPASY, KEGG, MEROPS, Metacyc, PDB, CAS registry number:


1. Theodoratou, E., Paschos, A., Magalon, A., Fritsche, E., Huber, R. and Bock, A. Nickel serves as a substrate recognition motif for the endopeptidase involved in hydrogenase maturation. Eur. J. Biochem. 267 (2000) 1995-1999. [PMID: 10727938]

2. Yang, F., Hu, W., Xu, H., Li, C., Xia, B. and Jin, C. Solution structure and backbone dynamics of an endopeptidase HycI from Escherichia coli: implications for mechanism of the [NiFe] hydrogenase maturation. J. Biol. Chem. 282 (2007) 3856-3863. [PMID: 17150961]

[EC created 2009]

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