PDBsum entry: 2zeh

Transferase

PDB id: 2zeh

Contents

Protein chains

323 a.a. *

Ligands

SO4 ×2

Metals

_ZN ×2

Waters ×867

* Residue conservation analysis

PDB id:

2zeh

Name:

Transferase

Title:

Crystal structure of the human glutaminyl cyclase mutant e20 angstrom resolution

Structure:

Glutaminyl-peptide cyclotransferase. Chain: a, b. Fragment: residues 33-361. Synonym: qc, glutaminyl-tRNA cyclotransferase, glutaminyl c glutamyl cyclase. Engineered: yes. Mutation: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Tissue: bone marrow. Gene: qpct. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Resolution:

1.80Å R-factor: 0.181 R-free: 0.207

Authors:

K.F.Huang,Y.R.Wang,E.C.Chang,T.L.Chou,A.H.Wang

Key ref:

K.F.Huang et al. (2007). A conserved hydrogen bond network in the catalytic center of animal glutaminyl cyclases is critical for catalysis. Biochem J, 411, 181-190. PubMed id: 18072935 DOI: 10.1042/BJ20071073

Date:

12-Dec-07 Release date: 22-Apr-08

Protein chains

Q16769  (QPCT_HUMAN) -  Glutaminyl-peptide cyclotransferase

Seq: 361 a.a.

Struc: 323 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

Enzyme reactions

• Enzyme class: E.C.2.3.2.5 - Glutaminyl-peptide cyclotransferase.
• Reaction: L-glutaminyl-peptide = 5-oxoprolyl-peptide + NH₃

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

 Gene Ontology (GO) functional annotation 

• Cellular component: extracellular region (1 term)
• Biological process: protein modification process (3 terms)
• Biochemical function: transferase activity (6 terms)

Added reference

DOI no: 10.1042/BJ20071073

Biochem J 411:181-190 (2007)

PubMed id: 18072935

A conserved hydrogen bond network in the catalytic center of animal glutaminyl cyclases is critical for catalysis.

K.F.Huang, Y.R.Wang, E.C.Chang, T.L.Chou, A.H.Wang.

ABSTRACT

Glutaminyl cyclases (QCs) catalyze the N-terminal pyroglutamate formation of numerous bioactive peptides and proteins. The enzymes were reported to be related to several pathological processes, such as amyloidotic diseases, osteoporosis, rheumatoid arthritis, and melanoma. The crystal structure of human QC revealed an unusual hydrogen bond (H-bond) network in the active site, formed by several highly conserved residues (Ser 160, Glu 201, Asp 248, Asp 305, and His 319), within which Glu 201 and Asp 248 were found to bind to substrate. In this study, we combine steady-state enzyme kinetic and X-ray structural analyses of eleven single-mutation human QCs to investigate the roles of the H-bond network in catalysis. Our results showed that disrupting one or both of the central H-bonds, i.e., Glu 201...Asp 305 and Asp 248...Asp 305, reduced the steady-state catalysis dramatically. The roles of these two COOH...COOH bonds on catalysis could be partly replaced by COOH...H 2O bonds, but not by COOH...CONH 2 bonds, reminiscent of the low-barrier Asp...Asp H-bond in the active site of pepsin-like aspartic peptidases. Mutations on Asp 305, a residue located at the center of the H-bond network, raised the K m value of the enzyme by 4.4~19-fold, but decreased the k cat value by 79~2842-fold, indicating that Asp 305 primarily plays a catalytic role. In addition, results from mutational studies on Ser 160 and His 319 suggest that these two residues might help stabilize the conformations of Asp 248 and Asp 305, respectively. These data allow us to propose an essential proton transfer between Glu 201, Asp 305, and Asp 248 during the catalysis of animal QCs.