胎盤組織 Cytidine Deaminase에 關한 硏究 (Ⅰ) : Purification & Characterization = Studies on Cytidine Deaminase from Human Placenta (Ⅰ)

다국어 초록 (Multilingual Abstract)

Cytidine deaminase has been partially purified from human term placenta approximately 26-fold by combination of ammoninm sulfate saturation, sephacryl S-300, DEAE-cellulose and hydroxyapatite chromatography, and then its properties have been investigated.
The enzyme shows a broad optimum pH from 5 to 9 and is heat-stable being, almost remained its activity by heat treatment at 70℃ for 8 minutes.
The enzyme activity is inhibited to 23% and 77% by 2 mM of Cu^2+ and Co^2+, respectively, but, other cations do not affect the enzyme activity.
The apparant Michaelis constant for cytidine and deoxycytidine are 74 uM and 69 uM, respectively.
Kinetic analysis of cytidine deminase in presence of 0.25 mM Cu^2+ shows that the nature of the inhibition to cytidine deaminase is competitive, considering that Vmax is independent while km value is increased.
The enzyme activity is completely inhibited by 0. 5 mM of p-hydroxymecuribenzoicacid(PHMB)but all of the activity is recovered in adding mercaptoethanol.
The enzyme activity is decreased about 50% in prescence of 5 mM of polyamines.
The enzyme activity is mainly located in the nuclei (80%) and cytosol(16%) fractions. he molecular weight of the enzyme is about 770, 000.