PMID- 11076507
OWN - NLM
STAT- MEDLINE
DCOM- 20001228
LR  - 20190613
IS  - 0006-2960 (Print)
IS  - 0006-2960 (Linking)
VI  - 39
IP  - 45
DP  - 2000 Nov 14
TI  - Structural influence of hydrophobic core residues on metal binding and 
      specificity in carbonic anhydrase II.
PG  - 13687-94
AB  - Aromatic residues in the hydrophobic core of human carbonic anhydrase II (CAII) 
      influence metal ion binding in the active site. Residues F93, F95, and W97 are 
      contained in a beta-strand that also contains two zinc ligands, H94 and H96. The 
      aromatic amino acids contribute to the high zinc affinity and slow zinc 
      dissociation rate constant of CAII [Hunt, J. A., and Fierke, C. A. (1997) J. 
      Biol. Chem. 272, 20364-20372]. Substitution of these aromatic amino acids with 
      smaller side chains enhances Cu(2+) affinity while decreasing Co(2+) and Zn(2+) 
      affinity [Hunt, J. A., Mahiuddin, A., & Fierke, C. A. (1999) Biochemistry 38, 
      9054-9062]. Here, X-ray crystal structures of zinc-bound F93I/F95M/W97V and 
      F93S/F95L/W97M CAIIs reveal the introduction of new cavities in the hydrophobic 
      core, compensatory movements of surrounding side chains, and the incorporation of 
      buried water molecules; nevertheless, the enzyme maintains tetrahedral zinc 
      coordination geometry. However, a conformational change of direct metal ligand 
      H94 as well as indirect (i.e., "second-shell") ligand Q92 accompanies metal 
      release in both F93I/F95M/W97V and F93S/F95L/W97M CAIIs, thereby eliminating 
      preorientation of the histidine ligands with tetrahedral geometry in the 
      apoenzyme. Only one cobalt-bound variant, F93I/F95M/W97V CAII, maintains 
      tetrahedral metal coordination geometry; F93S/F95L/W97M CAII binds Co(2+) with 
      trigonal bipyramidal coordination geometry due to the addition of azide anion to 
      the metal coordination polyhedron. The copper-bound variants exhibit either 
      square pyramidal or trigonal bipyramidal metal coordination geometry due to the 
      addition of a second solvent molecule to the metal coordination polyhedron. The 
      key finding of this work is that aromatic core residues serve as anchors that 
      help to preorient direct and second-shell ligands to optimize zinc binding 
      geometry and destabilize alternative geometries. These geometrical constraints 
      are likely a main determinant of the enhanced zinc/copper specificity of CAII as 
      compared to small molecule chelators.
FAU - Cox, J D
AU  - Cox JD
AD  - Roy and Diana Vagelos Laboratories, Department of Chemistry, University of 
      Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA.
FAU - Hunt, J A
AU  - Hunt JA
FAU - Compher, K M
AU  - Compher KM
FAU - Fierke, C A
AU  - Fierke CA
FAU - Christianson, D W
AU  - Christianson DW
LA  - eng
SI  - PDB/1FQL
SI  - PDB/1FQM
SI  - PDB/1FQN
SI  - PDB/1FQR
SI  - PDB/1FR4
SI  - PDB/1FR7
SI  - PDB/1FSN
SI  - PDB/1FSQ
SI  - PDB/1FSR
GR  - GM40602/GM/NIGMS NIH HHS/United States
GR  - GM45614/GM/NIGMS NIH HHS/United States
PT  - Journal Article
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Biochemistry
JT  - Biochemistry
JID - 0370623
RN  - 0 (Amino Acids)
RN  - 0 (Metals, Heavy)
RN  - 3G0H8C9362 (Cobalt)
RN  - 452VLY9402 (Serine)
RN  - 47E5O17Y3R (Phenylalanine)
RN  - 789U1901C5 (Copper)
RN  - 8DUH1N11BX (Tryptophan)
RN  - AE28F7PNPL (Methionine)
RN  - EC 4.2.1.1 (Carbonic Anhydrases)
RN  - GMW67QNF9C (Leucine)
RN  - HG18B9YRS7 (Valine)
RN  - J41CSQ7QDS (Zinc)
SB  - IM
MH  - Amino Acid Substitution
MH  - Amino Acids/*chemistry
MH  - Binding Sites
MH  - Carbonic Anhydrases/*chemistry/*metabolism
MH  - Cobalt/metabolism
MH  - Copper/metabolism
MH  - Crystallography, X-Ray
MH  - Humans
MH  - Leucine/chemistry
MH  - Metals, Heavy/*metabolism
MH  - Methionine/chemistry
MH  - Phenylalanine/chemistry
MH  - Serine/chemistry
MH  - Structure-Activity Relationship
MH  - Substrate Specificity
MH  - Tryptophan/chemistry
MH  - Valine/chemistry
MH  - Zinc/metabolism
EDAT- 2000/11/15 11:00
MHDA- 2001/02/28 10:01
CRDT- 2000/11/15 11:00
PHST- 2000/11/15 11:00 [pubmed]
PHST- 2001/02/28 10:01 [medline]
PHST- 2000/11/15 11:00 [entrez]
AID - bi001649j [pii]
AID - 10.1021/bi001649j [doi]
PST - ppublish
SO  - Biochemistry. 2000 Nov 14;39(45):13687-94. doi: 10.1021/bi001649j.