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Human placenta cytidine deaminase: proton‐linked enzyme activity and substrate binding
Author(s) -
Vincenzetti Silvia,
Angeletti Mauro,
Lupidi Giulio,
Cambi Alessandra,
Natalini Paolo,
Vita Alberto
Publication year - 1997
Publication title -
iubmb life
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.132
H-Index - 113
eISSN - 1521-6551
pISSN - 1521-6543
DOI - 10.1080/15216549700202881
Subject(s) - tetramer , chemistry , cytidine deaminase , substrate (aquarium) , enzyme , active site , stereochemistry , binding site , catalysis , monomer , biochemistry , tryptophan , cytidine , amino acid , organic chemistry , biology , ecology , polymer
In this work we focused our attention on some catalytic site requirements for human placenta cytidine deaminase (CDA). The effect of pH on substrate binding and catalysis was studied between pH 3.0 and pH 11.0. The results could be discussed postulating the presence of two classes of ionizable groups in the active site of CDA. The kinetic parameters pH‐dependence has been discussed considering the presence of four zinc atoms per each enzyme tetramer. Furthermore fluorescence studies on the enzyme and on enzyme‐inhibitor complexes, examined by using polar and non polar quenchers, allowed to define the substrate(inhibitor)‐dependent accessibility of the tryptophan‐containing pocket on each CDA monomer.