BIOMAT Database Logo BIOMAT Database Logo

Kinetic studies on 2',2'-difluorodeoxycytidine (Gemcitabine) with purified human deoxycytidine kinase and cytidine deaminase. 1993

D Y Bouffard, and J Laliberté, and R L Momparler
Département de Pharmacologie, Université de Montréal, Québec, Canada.

Phosphorylation of cytosine analogs by deoxycytidine kinase (dCK) and deamination by cytidine deaminase (CDA) are two important processes in the activation and elimination of these drugs. We have investigated the kinetic parameters of 2',2'-difluorodeoxycytidine (dFdC) using purified enzymes from human cells. Deoxycytidine (CdR) and dFdC had Km values of 1.5 and 4.6 microM for dCK, respectively. Feedback inhibition of dCK by deoxycytidine 5'-triphosphate (dCTP) was also studied. Our results show that dCTP produced a greater inhibition of the phosphorylation of dFdC than CdR with concentrations of dCTP ranging from 1 to 25 microM. dFdC was a good substrate for CDA. Kinetic studies with this enzyme gave Km values for CdR and dFdC of 46.3 and 95.7 microM, respectively. The effect of competitive inhibitors of CDA on the deamination of dFdC was also investigated. Diazepinone riboside was a more potent inhibitor than tetrahydrouridine using either CdR or dFdC as the substrate. Inhibitors of CDA could be useful in clinical trials in patients with cancer to increase the chemotherapeutic effectiveness of dFdC.

UI MeSH Term Description Entries
D007700 Kinetics The rate dynamics in chemical or physical systems.
D003564 Cytidine Deaminase An enzyme that catalyzes the deamination of cytidine, forming uridine. EC 3.5.4.5. Cytidine Aminohydrolase,Aminohydrolase, Cytidine,Deaminase, Cytidine
D003841 Deoxycytidine A nucleoside component of DNA composed of CYTOSINE and DEOXYRIBOSE. Cytosine Deoxyribonucleoside,Cytosine Deoxyriboside,Deoxyribonucleoside, Cytosine,Deoxyriboside, Cytosine
D003842 Deoxycytidine Kinase An enzyme that catalyzes reversibly the phosphorylation of deoxycytidine with the formation of a nucleoside diphosphate and deoxycytidine monophosphate. Cytosine arabinoside can also act as an acceptor. All natural nucleoside triphosphates, except deoxycytidine triphosphate, can act as donors. The enzyme is induced by some viruses, particularly the herpes simplex virus (HERPESVIRUS HOMINIS). EC 2.7.1.74. Kinase, Deoxycytidine
D003845 Deoxycytosine Nucleotides Cytosine nucleotides which contain deoxyribose as the sugar moiety. Deoxycytidine Phosphates,Nucleotides, Deoxycytosine,Phosphates, Deoxycytidine
D006207 Half-Life The time it takes for a substance (drug, radioactive nuclide, or other) to lose half of its pharmacologic, physiologic, or radiologic activity. Halflife,Half Life,Half-Lifes,Halflifes
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000093542 Gemcitabine A deoxycytidine antimetabolite used as an antineoplastic agent. 2',2'-Difluoro-2'-Deoxycytidine,2',2'-Difluorodeoxycytidine,2'-Deoxy-2',2''-Difluorocytidine-5'-O-Monophosphate,2'-Deoxy-2'-Difluorocytidine,Gemcitabine Hydrochloride,Gemcitabine, (D-threo-pentafuranosyl)-Isomer,Gemcitabine, (alpha-D-threo-pentofuranosyl)-Isomer,Gemcitabine, (beta-D-threo-pentafuranosyl)-Isomer,Gemicitabine,2',2'-DFDC,Gemzar,LY 188011,LY-188011,dFdCyd,188011, LY,2' Deoxy 2' Difluorocytidine,2' Deoxy 2',2'' Difluorocytidine 5' O Monophosphate,Hydrochloride, Gemcitabine
D000964 Antimetabolites, Antineoplastic Antimetabolites that are useful in cancer chemotherapy. Antineoplastic Antimetabolites
D001381 Azepines Seven membered heterocyclic rings containing a NITROGEN atom. Hexamethyleneimines

Related Publications

D Y Bouffard, and J Laliberté, and R L Momparler
Pharmacogenomics of gemcitabine metabolism: functional analysis of genetic variants in cytidine deaminase and deoxycytidine kinase.
March 2013, Drug metabolism and disposition: the biological fate of chemicals,
D Y Bouffard, and J Laliberté, and R L Momparler
Regulation of phosphorylation of deoxycytidine and 2',2'-difluorodeoxycytidine (gemcitabine); effects of cytidine 5'-triphosphate and uridine 5'-triphosphate in relation to chemosensitivity for 2',2'-difluorodeoxycytidine.
April 1996, Biochemical pharmacology,
D Y Bouffard, and J Laliberté, and R L Momparler
A comparison of the enantioselectivities of human deoxycytidine kinase and human cytidine deaminase.
November 1998, Biochemical pharmacology,
D Y Bouffard, and J Laliberté, and R L Momparler
Drug resistance to 5-aza-2'-deoxycytidine, 2',2'-difluorodeoxycytidine, and cytosine arabinoside conferred by retroviral-mediated transfer of human cytidine deaminase cDNA into murine cells.
January 1998, Cancer chemotherapy and pharmacology,
D Y Bouffard, and J Laliberté, and R L Momparler
Role of deoxycytidine kinase (dCK), thymidine kinase 2 (TK2), and deoxycytidine deaminase (dCDA) in the antitumor activity of gemcitabine (dFdC).
January 1998, Advances in experimental medicine and biology,
D Y Bouffard, and J Laliberté, and R L Momparler
Deoxycytidine kinase and deoxycytidine deaminase activities in human tumour xenografts.
January 1993, European journal of cancer (Oxford, England : 1990),
D Y Bouffard, and J Laliberté, and R L Momparler
Detection of an alternatively spliced form of deoxycytidine kinase mRNA in the 2'-2'-difluorodeoxycytidine (gemcitabine)-resistant human ovarian cancer cell line AG6000.
August 2004, Biochemical pharmacology,
D Y Bouffard, and J Laliberté, and R L Momparler
Cytotoxic activity of 2',2'-difluorodeoxycytidine, 5-aza-2'-deoxycytidine and cytosine arabinoside in cells transduced with deoxycytidine kinase gene.
May 2002, Biochemical and biophysical research communications,
D Y Bouffard, and J Laliberté, and R L Momparler
Kinetic studies on phosphorylation of 5-azacytidine with the purified uridine-cytidine kinase from calf thymus.
October 1974, Cancer research,
D Y Bouffard, and J Laliberté, and R L Momparler
Studies on thermal stability of human cytidine deaminase.
January 2007, Nucleosides, nucleotides & nucleic acids,
Copied contents to your clipboard!