Nucleoside diphosphate kinase (Ndk) is ubiquitous and highly conserved multifunctional key enzyme in nucleotide metabolism. It generates nucleoside triphosphates (NTPs) by transfer of gamma-phosphates from nucleoside triphosphates such as ATP or GTP to nucleoside diphosphate. The formation of an autophosphorylated enzyme intermediate is involved in that mechanism. The phosphate is usually supplied by ATP and Ndk activity in different subcellular compartments. Ndk may regulate the crucial balance between ATP and GTP or other nucleoside triphosphates. Ndk is playing an important role in bacterial pathogenesis and emerging evidences recognize multiple roles of Ndk in host-microbe interaction. Here, I review some examples of the role of Ndk in intra- and extracellular microorganism.
Adenosine Triphosphate ; Guanosine Triphosphate ; Nucleoside-Diphosphate Kinase

No abstract available.
Carrier Proteins ; Guanosine Triphosphate ; Signal Transduction

The energy metabolism of the brain has been measured in cat model using high performance liquid chromatography(HPLC). The experimental groups were divided into three according to the duration of ischemia. In 1- and 3-hour ischemia groups, recirculation had increased the ATP, UTP and GTP significantly to 39-49%, 53-57% and 39-62% of the sham control value respectively. Also in these groups, recirculation had increased adenylate energy charge(E.C.) to 75-82% of sham control value. Whereas there were slight increase in adenylate E.C. after recirculation in 5-hr ischemia group, with the remainders not increasing significantly. The Na+, K+-ATPase activities were not significant statistically among the groups. These results suggest that in order to prevent from the irreversible ischemic brain damage, restoration of blood flow must be accomplished within 3 hours from the onset of the acute focal ischemia in cat.
Adenosine Triphosphate ; Animals ; Brain ; Cats ; Chromatography, High Pressure Liquid ; Energy Metabolism* ; Guanosine Triphosphate ; Ischemia ; Uridine Triphosphate

The study was designed to examine the effects of pretreatment with mannitol, methyl prednisolone and nimodipine on the acute focal cerebral ischemia in the cats of occlusion of the proximal part of the middle cerebral artery via the postorbital approach. The energy metabolisms of the brain was measured utilizing the high liquid performance chromatography in the brain tissues of cats. The experimental animals were seperated into 3 groups. group I: the sham control group. group II: the recirculation group. group III: the treatment group. There were significant increase in the ATP, GTP, UTP and E.C. levels in focal ischemic cerebral tissues of the treatment group when compared with the recirculation group. It is suggested that pretreatment with the combination of these drugs may prevent the ischemic damage from the acute focal cerebral ischemia by the maintenance of high energy metabolites. However further studies should determine the synergistic pharmacologic mechanisms in this therapeutic strategy.
Adenosine Triphosphate ; Animals ; Brain ; Brain Ischemia* ; Cats ; Chromatography ; Energy Metabolism ; Guanosine Triphosphate ; Mannitol ; Middle Cerebral Artery ; Nimodipine ; Prednisolone ; Uridine Triphosphate

The author studied the effect of the recirculation on the energy metabolism in acute focal cerebral ischemia. Acute focal cerebral ischemia was produced by transorbital occlusion of the left middle cerebral artery with a Heifetz clip under the operating microscope. The animals were divided into three groups according to the duration of the ischemia. Each group was reperfused for 1, 4 and 7 hour by removing the clip from the artery. In 1-hour ischemic group ATP and GTP was reduced to 38% and IMP to 40% of the sham control. After 7-hour recirculation in this group ATP was resynthesized to 85%, GTP to 85%, and IMP to 180% of the sham control. In 3-hour ischemic group ATP was reduced to 19%, GTP to 23%, and IMP to 29% of the sham control. In this group ATP, GTP and IMP rose to 43%, 49% and 84%, respectively after 7-hour recirculation ATP, GTP and IMP were markedly reduced in 5-hour ischemic group, and despite recirculation these substances continued to decrease and none of them were detected after 7-hours of recirculation, It was suggested that the restoration of the circulation must be accomplished within 1-hour or at least within 3-hour of the ischemic insult of the cats to prevent the irreversible brain infarction.
Adenosine Triphosphate ; Animals ; Arteries ; Brain Infarction ; Brain Ischemia ; Cats ; Edema* ; Energy Metabolism* ; Guanosine Triphosphate ; Ischemia ; Middle Cerebral Artery

In lepromatous leprosy, it is generally believed that there is not only defective CMl specific for M. leprae, but also generalized impairment of CMI and in erythema nodosum leprosum, an immune complex-mediated pathogenesis as well cell mediated immune pathogenesis have been proposed. Neopterin is a pyrazinopyrirnidine compound derived from GTP, its raised excretion has been related to activation of T-lymphocyte/macrophage axis. A study was performed to evaluate generalized CMI status in the LL and ENL and to investigate a relationship between levels of urinary neopterin and disease activity. Urinary neopterin was measured by high pressure liquid chromatography in 25 healthy subjects, in 25 patients with LL and in 25 patients with ENL. The results were as follaws 1. Urinary Neopterin levels of patients with LL was 188.9+147.3umol/mol creatinine, which was higher than that of control group(144.8+40.4umol/mol creatinine)(p<0.01). 2. Urinary Neopterin levels of patients with ENL was 884.1+970.5umol/mol creatinine, which was higher than of control group, and patients with LL(p<0.01, p<0.01). 3. Serial measurement of urinary neopterin from 1 week to 13 weeks after treatment of ENL in 4 cases of ENL showed good correlation between urinary neopterin levels and disease activity. In summary, it thus appears that measurement of urine neopterin in leprosy provides generalized CMI status and reliable index for activity of disease.
Axis, Cervical Vertebra ; Chromatography, Liquid ; Creatinine ; Erythema Nodosum* ; Erythema* ; Guanosine Triphosphate ; Humans ; Leprosy ; Leprosy, Lepromatous* ; Neopterin*

GTP binding protein (G-protein) associated with membrane and involved in signal transduction was isolated from bovine brain, and molecular weight of G protein was observed. As the results, cell membranes were homogenized from bovine brain tissues and proteins of membrane were gained using 1% cholate, and progressed the chromatography. The purification process was performed by step, DEAE-Sephacel, Ulttrogel AcA 34 and heptylamine-Sepharose column chromatography. The chromatographic fractions were confirmed by GTP binding assay and SDS-polyacrylamide gel electrophoresis. Molecular weight of Goa was revealed 39,000 dalton and GR 36,000 dalton. One more step of heptylamine-Sepharose was enforced to purify the GTP binding protein. Finally I gained the GTP binding protein isolated subtype of Goalpha and Gbeta.
Brain* ; Cell Membrane ; Cholates ; Chromatography ; Electrophoresis ; GTP-Binding Proteins ; Guanosine Triphosphate* ; Membranes ; Molecular Weight ; Signal Transduction

OBJECTIVE: The chemotherapeutic agent cisplatin (cis-diamminedichloroplatinum (II)) is particularly effective against cervical cancer. The purpose of this study is to elucidate combination effect of cisplatin and green tea extracts on the growth inhibition of TC-1 cell. METHODS: To observe the anti-proliferative effects, we treated different doses of cisplatin (0.1, 0.5, 2.5 uM), GTP (1, 5, 25 ug/ml) and EGCG (25, 50, 100 uM). to TC-1 cells. Also, we treated 0.5 uM of cisplatin and different doses of GTP (1 and 5 ug/ml) or EGCG (25 and 50 uM). Cell viability was scored by use of MTT assay. In addition, E6 gene expression patterns in TC-1 cell were investigated by using RT-PCR. RESULTS: Cell growth inhibition in a dose dependent was observed at the different concentration of ciaplatin, GTP and EGCG. Also, in the groups treated by 0.5 uM of cisplatin and GTP (1 and 5 ug/ml) or EGCG (25 and 50 uM), the inhibition of cell growth showed with 12.2%, 6.9% and 63.4%, 72.2% as compared to the group treated by cisplatin only. In RT-PCR, down regulation of E6 was shown. CONCLUSION: Additive effect of the combination of cisplatin with GTP or EGCG on the inhibition of cell growth was observed. This effect suggests the possibility lowering the concentration of chemotherapeutic drugs, which alleviate the side effect of drugs.
Cell Survival ; Cisplatin* ; Down-Regulation ; Gene Expression ; Guanosine Triphosphate ; Tea* ; Uterine Cervical Neoplasms

This study was designed to clarify the mechanism of the inhibitory effect of forskolin on contraction, cytosolic Ca2+ level ([Ca2+]i), and Ca2+ sensitivity in guinea pig ileum. Forskolin (0.1 nM~10 micrometer) inhibited high K+ (25 mM and 40 mM)- or histamine (3 micrometer)-evoked contractions in a concentration-dependent manner. Histamine-evoked contractions were more sensitive to forskolin than high K+-evoked contractions. Spontaneous changes in [Ca2+]i and contractions were inhibited by forskolin (1 micrometer) without changing the resting [Ca2+]i. Forskoln (10 micrometer) inhibited muscle tension more strongly than [Ca2+]i stimulated by high K+, and thus shifted the [Ca2+]i-tension relationship to the lower-right. In histamine-stimulated contractions, forskolin (1 micrometer) inhibited both [Ca2+]i and muscle tension without changing the [Ca2+]i-tension relationship. In alpha-toxin-permeabilized tissues, forskolin (10 micrometer) inhibited the 0.3 micrometer Ca2+-evoked contractions in the presence of 0.1 mM GTP, but showed no effect on the Ca2+-tension relationship. We conclude that forskolin inhibits smooth muscle contractions by the following two mechanisms: a decrease in Ca2+ sensitivity of contractile elements in high K+-stimulated muscle and a decrease in [Ca2+]i in histamine-stimulated muscle.
Animals ; Contracts ; Cytosol ; Forskolin ; Guanosine Triphosphate ; Guinea ; Guinea Pigs ; Histamine ; Ileum ; Muscle Tonus ; Muscle, Smooth ; Muscles

RalA GTPase, a member of Ras superfamily proteins, shows alternative forms between the active GTP-binding and the inactive GDP-binding states. Ral-specific guanine nucleotide exchange factor such as RalGDS interacts with activated Ras and cooperates with Ras indicating that Ral can be activated through Ras signaling pathway. Another activation path for Ral are through Ca2+-dependent but Ras-independent manner. In this study, studies were carried out to examine possible effects of Ca2+ and calmodulin, Ca2+-binding protein, directly on the GTP/GDP-binding state to recombinant unprenylated GST-RalA proteins. The results showed that Ca2+ stimulated the binding of GTP to RalA, whereas it reduced the binding of GDP to RalA. However, it does not involve a high affinity association of Ca2+ with RalA. Ca2+/calmodulin stimulated the GTPase activity of RalA. These results indicate that Ca2+ alone activates RalA by stimulating GTP-binding to RalA and Ca2+/calmodulin inactivates RalA by increasing the activity of RalGTPase.
Animal ; Brain/metabolism ; Calcium/*metabolism ; Calmodulin/*metabolism ; GTP Phosphohydrolases/*metabolism ; Guanosine Diphosphate/metabolism ; Guanosine Triphosphate/*metabolism ; Rats ; Support, Non-U.S. Gov't ; Synaptosomes/metabolism