PMID- 8771178
OWN - NLM
STAT- MEDLINE
DCOM- 19961025
LR  - 20190909
IS  - 0269-2139 (Print)
IS  - 0269-2139 (Linking)
VI  - 8
IP  - 10
DP  - 1995 Oct
TI  - Structure of His94-->Asp carbonic anhydrase II in a new crystalline form reveals 
      a partially occupied zinc binding site.
PG  - 975-80
AB  - The structure of histidine 94-->aspartate (H94D) carbonic anhydrase II (CAII) 
      crystallized in an orthorhombic space group has been determined to 2.5 A 
      resolution. This crystal form is not isomorphous with monoclinic wild-type enzyme 
      crystals or with the monoclinic crystal form of H94D CAII reported earlier 
      [Kiefer,L.L., Ippolito, J.A., Fierke, C.A. and Christianson, D.W. (1993) J. Am. 
      Chem. Soc., 115, 12581-12582]. In monoclinic H94D CAII, a fully occupied zinc ion 
      is tetrahedrally coordinated by D94, H96, H119 and a water molecule. In 
      orthorhombic H94D CAII, a partially occupied zinc ion is coordinated by H96 and 
      H119 and only weakly coordinated by a disordered D94 side chain. These 
      differences are particularly surprising given that the two crystal forms 
      co-precipitate in the same drop in the same experiment. Re-refinement of the 
      orthorhombic crystal form of H94C CAII and comparison with its corresponding 
      monoclinic crystal form yield similar results. It appears that partial-but not 
      full-zinc dissociation accompanies the crystallization of CAII variants in the 
      orthorhombic crystal form, and significant differences on the protein surface 
      presumably affect the relative stability of each crystal lattice. These results 
      underscore an unexpected ambiguity in this protein engineering experiment: which 
      crystal structure of H94D CAII should be correlated with functional measurements 
      made in solution?
FAU - Ippolito, J A
AU  - Ippolito JA
AD  - Department of Chemistry, University of Pennsylvania, Philadelphia 19104-6323, 
      USA.
FAU - Nair, S K
AU  - Nair SK
FAU - Alexander, R S
AU  - Alexander RS
FAU - Kiefer, L L
AU  - Kiefer LL
FAU - Fierke, C A
AU  - Fierke CA
FAU - Christianson, D W
AU  - Christianson DW
LA  - eng
PT  - Journal Article
PT  - Research Support, U.S. Gov't, Non-P.H.S.
PL  - England
TA  - Protein Eng
JT  - Protein engineering
JID - 8801484
RN  - EC 4.2.1.1 (Carbonic Anhydrases)
RN  - J41CSQ7QDS (Zinc)
SB  - IM
MH  - Binding Sites
MH  - Carbonic Anhydrases/*chemistry/genetics/metabolism
MH  - Crystallization
MH  - Crystallography, X-Ray
MH  - Electrochemistry
MH  - Humans
MH  - In Vitro Techniques
MH  - Models, Molecular
MH  - Molecular Structure
MH  - Mutagenesis, Site-Directed
MH  - Point Mutation
MH  - Protein Conformation
MH  - Protein Engineering
MH  - Zinc/metabolism
EDAT- 1995/10/01 00:00
MHDA- 1995/10/01 00:01
CRDT- 1995/10/01 00:00
PHST- 1995/10/01 00:00 [pubmed]
PHST- 1995/10/01 00:01 [medline]
PHST- 1995/10/01 00:00 [entrez]
AID - 10.1093/protein/8.10.975 [doi]
PST - ppublish
SO  - Protein Eng. 1995 Oct;8(10):975-80. doi: 10.1093/protein/8.10.975.