PDBsum entry 4l5u

Lyase

PDB id: 4l5u

Contents

Protein chain

257 a.a.

Ligands

GOL

Metals

_ZN

Waters ×209

PDB id:

4l5u

Name:

Lyase

Title:

The structural implications of the secondary co2 binding pocket in human carbonic anhydrase ii

Structure:

Carbonic anhydrase 2. Chain: a. Synonym: carbonate dehydratase ii, carbonic anhydrasE C, cac, carbonic anhydrase ii, ca-ii. Engineered: yes. Mutation: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: ca2. Expressed in: escherichia coli. Expression_system_taxid: 562

Resolution:

2.05Å R-factor: 0.156 R-free: 0.201

Authors:

C.D.Boone,S.Gill,R.Mckenna

Key ref:

C.D.Boone et al. (2013). Structural, catalytic and stabilizing consequences of aromatic cluster variants in human carbonic anhydrase II. Arch Biochem Biophys, 539, 31-37. PubMed id: 24036123 DOI: 10.1016/j.abb.2013.09.001

Date:

11-Jun-13 Release date: 30-Apr-14

Protein chain

P00918  (CAH2_HUMAN) -  Carbonic anhydrase 2 from Homo sapiens

Seq: 260 a.a.

Struc: 257 a.a.*

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

Enzyme reactions

• Enzyme class 2: E.C.4.2.1.1 - carbonic anhydrase.
• Reaction: hydrogencarbonate + H⁺ = CO2 + H2O
• Cofactor: Zn(2+)
• Enzyme class 3: E.C.4.2.1.69 - cyanamide hydratase.
• Reaction: urea = cyanamide + H2O

Note, where more than one E.C. class is given (as above), each may correspond to a different protein domain or, in the case of polyprotein precursors, to a different mature protein.

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

reference

DOI no: 10.1016/j.abb.2013.09.001

Arch Biochem Biophys 539:31-37 (2013)

PubMed id: 24036123

Structural, catalytic and stabilizing consequences of aromatic cluster variants in human carbonic anhydrase II.

C.D.Boone, S.Gill, C.Tu, D.N.Silverman, R.McKenna.

ABSTRACT

The presence of aromatic clusters has been found to be an integral feature of many proteins isolated from thermophilic microorganisms. Residues found in aromatic cluster interact via π-π or C-H⋯π bonds between the phenyl rings, which are among the weakest interactions involved in protein stability. The lone aromatic cluster in human carbonic anhydrase II (HCA II) is centered on F226 with the surrounding aromatics F66, F95 and W97 located 12 Å posterior the active site; a location which could facilitate proper protein folding and active site construction. The role of F226 in the structure, catalytic activity and thermostability of HCA II was investigated via site-directed mutagenesis of three variants (F226I/L/W) into this position. The measured catalytic rates of the F226 variants via (18)O-mass spectrometry were identical to the native enzyme, but differential scanning calorimetry studies revealed a 3-4 K decrease in their denaturing temperature. X-ray crystallographic analysis suggests that the structural basis of this destabilization is via disruption and/or removal of weak C-H⋯π interactions between F226 to F66, F95 and W97. This study emphasizes the importance of the delicate arrangement of these weak interactions among aromatic clusters in overall protein stability.