Open AccessThe Purification and Properties of Cytidine Aminohydrolase from Sheep Liver
Author(s) -
Wisdom G. B.,
Orsi B. A.
Publication year - 1969
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1969.tb19595.x
Subject(s) - enzyme , chemistry , biochemistry , deamination , cytidine , yield (engineering) , substrate (aquarium) , chromatography , biology , ecology , materials science , metallurgy
Cytidine aminohydrolase was purified about 280‐fold with an overall 8% yield from the cytoplasmic fraction of sheep liver cells by the use of protamine sulphate precipitation, salt fractionation using trisodium citrate, acidification and chromatography on DEAE‐and CM‐celluloses. The enzyme catalyses the deamination of several aminopyrimidine nucleosides. Its pH optimum occurred at 5.0 and it was relatively acid and heat stable. The high sensitivity of the enzyme to compounds known to react with sulphydryl groups and the presence of a substrate‐binding group of pK a 9.2 in the enzyme suggests that a sulphydryl group may be important in the catalytic process. dTTP and dUTP were found to inhibit and dCTP to activate the enzyme respectively. The complex type of inhibition produced by dTTP indicates that this aminohydrolase may have a regulatory role similar to that of dCMP aminohydrolase.