PMID- 7696263
OWN - NLM
STAT- MEDLINE
DCOM- 19950502
LR  - 20190613
IS  - 0006-2960 (Print)
IS  - 0006-2960 (Linking)
VI  - 34
IP  - 12
DP  - 1995 Mar 28
TI  - Structural basis of inhibitor affinity to variants of human carbonic anhydrase 
      II.
PG  - 3981-9
AB  - The activities and structures of certain L198 variants of human carbonic 
      anhydrase II (CAII) have been reported recently [Krebs, J. F., Rana, F., Dluhy, 
      R. A., & Fierke, C. A. (1993) Biochemistry 32, 4496-4505; Nair, S. K., & 
      Christianson, D. W. (1993) Biochemistry 32, 4506-4514]. In order to understand 
      the structural basis of enzyme-inhibitor affinity, we now report the dissociation 
      rate and equilibrium constants for acetazolamide and dansylamide binding to 13 
      variants of CAII containing substituted amino acids at position 198. These data 
      indicate that inhibitor affinity is modulated by the hydrophobicity and charge of 
      the 198 side chain. Furthermore, we have determined crystal structures of L198R, 
      L198E, and L198F CAIIs complexed with the transition state analog acetazolamide. 
      The substituted benzyl side chain of L198F CAII does not occlude the substrate 
      association pocket, and it is therefore not surprising that this substitution has 
      minimal effects on catalytic properties and inhibitor binding. Nevertheless, the 
      F198 side chain undergoes a significant conformation change in order to 
      accommodate the binding of acetazolamide; the same behavior is observed for the 
      engineered side chain of L198R CAII. In contrast, the engineered side chain of 
      L198E CAII does not alter its conformation upon inhibitor binding. We conclude 
      that the mobility and hydrophobicity or residue 198 side chains affect 
      enzyme-inhibitor (and enzyme-substrate) affinity, and these structure-function 
      relationships are important for understanding the behavior of carbonic anhydrase 
      isozyme III, which bears a wild-type F198 side chain.(ABSTRACT TRUNCATED AT 250 
      WORDS)
FAU - Nair, S K
AU  - Nair SK
AD  - Department of Chemistry, University of Pennsylvania, Philadelphia 19104-6323.
FAU - Krebs, J F
AU  - Krebs JF
FAU - Christianson, D W
AU  - Christianson DW
FAU - Fierke, C A
AU  - Fierke CA
LA  - eng
GR  - GM07229/GM/NIGMS NIH HHS/United States
GR  - GM40602/GM/NIGMS NIH HHS/United States
GR  - GM45614/GM/NIGMS NIH HHS/United States
PT  - Comparative Study
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, Non-P.H.S.
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Biochemistry
JT  - Biochemistry
JID - 0370623
RN  - 0 (Carbonic Anhydrase Inhibitors)
RN  - 0 (Dansyl Compounds)
RN  - 0 (Recombinant Proteins)
RN  - 1431-39-6 (5-dimethylaminonaphthalene-1-sulfonamide)
RN  - EC 4.2.1.1 (Carbonic Anhydrases)
RN  - GMW67QNF9C (Leucine)
RN  - O3FX965V0I (Acetazolamide)
SB  - IM
MH  - Acetazolamide/metabolism
MH  - Binding Sites
MH  - Carbonic Anhydrase Inhibitors/*metabolism
MH  - Carbonic Anhydrases/*chemistry/*metabolism
MH  - Dansyl Compounds/metabolism
MH  - Fourier Analysis
MH  - Humans
MH  - Kinetics
MH  - *Leucine
MH  - Models, Molecular
MH  - Mutagenesis, Site-Directed
MH  - *Protein Conformation
MH  - Recombinant Proteins/chemistry/metabolism
EDAT- 1995/03/28 00:00
MHDA- 1995/03/28 00:01
CRDT- 1995/03/28 00:00
PHST- 1995/03/28 00:00 [pubmed]
PHST- 1995/03/28 00:01 [medline]
PHST- 1995/03/28 00:00 [entrez]
AID - 10.1021/bi00012a016 [doi]
PST - ppublish
SO  - Biochemistry. 1995 Mar 28;34(12):3981-9. doi: 10.1021/bi00012a016.