Adenosine triphosphate (ATP) regeneration systems are essential for efficient biocatalytic phosphoryl transfer reactions. Polyphosphate kinase (PPK) is a versatile enzyme that can transfer phosphate groups among adenosine monophosphate (AMP), adenosine diphosphate (ADP), ATP, and polyphosphate (Poly P). Utilization of PPK is an attractive solution to address the problem of ATP regeneration due to its ability to use a variety of inexpensive and stable Poly P salts as phosphate group donors. This review comprehensively summarizes the structural characteristics and catalytic mechanisms of different types of PPKs, as well as the variations in enzyme activity, catalytic efficiency, stability, and coenzyme preference observed in PPKs from different sources. Moreover, recent advances in PPK-mediated ATP regeneration systems and protein engineering of wild-type PPK are summarized.
Adenosine Triphosphate/metabolism* ; Adenosine Monophosphate ; Polyphosphates/metabolism* ; Catalysis ; Regeneration

Adenosine 5'-monophosphate-activated protein activated protein kinase (AMPK), a heterotrimeric complex, is an important kinase to regulate glycolipid metabolism and energy balance involved in a variety physiological processes in human body. Many research indicated that the function and activity of AMPK were closely related to inflammation, diabetes and cancers. Recent reports show that inhibition of metformin (a first-line drug) on hepatic glucose in patients with hyperglycemia is associated with AMPK pathway, suggesting that targeting AMPK may be one of the effective strategies for the prevention and treatment of a variety of chronic diseases. Here, we review research progress on the structure, activation and regulation of AMPK in glycolipid metabolism to provide an insight into the basic and clinical research of diabetes therapy.
AMP-Activated Protein Kinases ; Adenosine ; Adenosine Monophosphate ; Energy Metabolism ; Enzyme Activation ; Glycolipids ; Humans

OBJECTIVETo investigate the role of cyclic adenosine monophosphate(cAMP) in the regulation of intestinal epithelial barrier function under hypoxia.

METHODSIntestinal epithelial barrier was established by Caco-2 monolayers. Cells were divided into four groups: normoxia (Nx), normoxia plus Forskolin(Nx+FSK), hypoxia(Hx), hypoxia plus SQ22536(Hx+SQ22536). cAMP concentrations of different groups were assessed by cAMP enzyme immunoassay kit. RT-PCR and Western blotting were used to detect the mRNA and protein expressions of claudin-1 and occludin under normoxic and hypoxic condition. Caco-2 monolayers were grown on Millicell filters, and transepithelial electrical resistance(TER) was measured using a Millipore electric resistance system.

RESULTSThe concentration of cAMP under hypoxic conditions(Hx group) was higher compared with Nx group [(6.30±0.50) pmol/L vs. (2.38±0.18) pmol/L, P<0.01]. At the same time, both mRNA and protein expressions of claudin-1 and occluding were lower in Hx group than those in Nx group(all P<0.05). TER decreased by 76.30±0.64(P<0.01). When the monolayers were exposed to hypoxia plus SQ22536 (Hx+SQ22536 group), the concentration of cAMP was(2.12±0.23) pmol/L, which was lower than that under hypoxic conditions(Hx group, P<0.01). Both mRNA and protein expressions of claudin-1 and occludin were higher compared to Hx group (all P<0.01). TER increased by 32.96±2.16 (P<0.05).

CONCLUSIONWhen Caco-2 cells are exposed to hypoxia, barrier function, claudin-1 and occludin expression are diminished in parallel with a high level of intracellular cAMP compared with the normoxic condition. Inhibition of the intracellular cAMP level under hypoxia can maintain the intestinal epithelial function through regulating the claudin-1 and occludin expression and attenuate the permeability of intestinal mucosa.

Adenosine Monophosphate ; Caco-2 Cells ; Claudin-1 ; metabolism ; Humans ; Intestinal Mucosa ; metabolism ; Intestines ; Occludin ; metabolism

AMP-Activated Protein Kinases/metabolism* ; Adenosine Monophosphate/metabolism* ; Kidney/metabolism* ; Phosphorylation

Adenosine Monophosphate ; metabolism ; Genetic Pleiotropy ; HSP70 Heat-Shock Proteins ; metabolism ; Humans ; Neurodegenerative Diseases ; metabolism

Chinese hamster ovary (CHO) cells are the preferred host cells for the production of complex recombinant therapeutic proteins. Adenine phosphoribosyltransferase (APRT) is a key enzyme in the purine biosynthesis step that catalyzes the condensation of adenine with phosphoribosylate to form adenosine phosphate AMP. In this study, the gene editing technique was used to knock out the aprt gene in CHO cells. Subsequently, the biological properties of APRT-KO CHO cell lines were investigated. A control vector expressed an enhanced green fluorescent protein (EGFP) and an attenuation vector (containing an aprt-attenuated expression cassette and EGFP) were constructed and transfected into APRT-deficient and wild-type CHO cells, respectively. The stable transfected cell pools were subcultured for 60 generations and the mean fluorescence intensity of EGFP in the recombinant CHO cells was detected by flow cytometry to analyze the EGFP expression stability. PCR amplification and sequencing showed that the aprt gene in CHO cell was successfully knocked out. The obtained APRT-deficient CHO cell line had no significant difference from the wild-type CHO cells in terms of cell morphology, growth, proliferation, and doubling time. The transient expression results indicated that compared with the wild-type CHO cells, the expression of EGFP in the APRT-deficient CHO cells transfected with the control vector and the attenuation vector increased by 42%±6% and 56%±9%, respectively. Especially, the EGFP expression levels in APRT-deficient cells transfected with the attenuation vector were significantly higher than those in wild-type CHO cells (P < 0.05). The findings suggest that the APRT-deficient CHO cell line can significantly improve the long-term expression stability of recombinant proteins. This may provide an effective cell engineering strategy for establishing an efficient and stable CHO cell expression system.
Adenine/metabolism* ; Adenine Nucleotides ; Adenine Phosphoribosyltransferase/genetics* ; Adenosine Monophosphate ; Animals ; CHO Cells ; Cricetinae ; Cricetulus ; Recombinant Proteins/genetics*

OBJECTIVE: The content changes of energy substances in the cardiac muscle of rat killed by different manners were investigated to elucidate evidence that can be used to determine the modes of death and postmortem interval. METHODS: One hundred and eighty rats were randomly allocated into 3 groups and killed by bleeding, suffocating, and neck breaking, respectively. The contents of ATP, ADP, and AMP in the cardiac muscle of rats killed by the different manners at different death intervals (0, 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12, 18, and 24 h) were measured by HPLC. RESULTS: There were significant differences observed in the contents of ATP and AMP in the rats' cardiac muscle in different groups at most of the intervals (P < 0.05) and at all of the intervals within the same group (P < 0.01), but no differences were found in the ADP contents in any of the group at most of the intervals. CONCLUSION The content changes of energy substances (ATP and AMP) in the cardiac muscle of dead rats may provide a basis for determination of the death manners and postmortem intervals.
Adenosine Diphosphate/metabolism* ; Adenosine Monophosphate/metabolism* ; Adenosine Triphosphate/metabolism* ; Animals ; Asphyxia/metabolism* ; Cause of Death ; Cervical Vertebrae/injuries* ; Chromatography, High Pressure Liquid ; Female ; Male ; Myocardium/pathology* ; Postmortem Changes ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Shock, Hemorrhagic/metabolism* ; Time Factors

AMP-Activated Protein Kinases/metabolism* ; Adenosine ; Adenosine Monophosphate ; Cell Proliferation ; Endometrial Neoplasms/drug therapy* ; Female ; Humans ; Liraglutide ; Phosphorylation ; Protein Kinases ; Signal Transduction

OBJECTIVETo observe the effect of salvianolic acid B (SalB) on high energy phosphate and activity of ATPase of cerebral ischemia in mice, and to study the role of SalB on hydrocephalus further.

METHODNIH mice were divided into four groups randomly: Sham-operated group, cerebral ischemia group, SalB-treated group and Nimodipine (Nim)-collated group. In Sal B-treated group, mice were injected with SalB (22.5 mg x kg(-1)) in vena caudalis at 30 min before the experiment. In Nim-collated group, Nim (0.03 mg x kg(-1)) was injected into tail vein at the same time, while the mice in Sham-operated group and cerebral ischemia group were injected the same volume normal saline. The acute cerebral ischemia model was established by ligating bilateral common carotid arteries for 30 min in mice, then the mice were killed and the content of adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP), phosphocreatine (PCr) were observed, and the cerebral energy charge (EC) was computed. At the same time, activity of Na(+) -K(+) -ATPase and Ca2(+) -ATPase, content of water in brain tissue were measured.

RESULTCompared with cerebral ischemia group, EC and content of ATP, ADP, PCr in SalB-treated group heightened evidently (P < 0.01). Moreover, activity of Na(+)-K+ ATPase and Ca2+ ATPase in SalB-treated group had a remarkable increase (P < 0.01). But the content of water in brain tissue decreased markedly (P < 0.05).

CONCLUSIONThe mechanism that SalB can relieve content of water in brain tissue of cerebral ischemia in mice, may be associated with improving the content of high-energy phosphoric acid compounds and enhancing the activity of ATPase.

Adenosine Diphosphate ; metabolism ; Adenosine Monophosphate ; metabolism ; Adenosine Triphosphatases ; metabolism ; Adenosine Triphosphate ; metabolism ; Animals ; Benzofurans ; isolation & purification ; pharmacology ; Brain ; drug effects ; metabolism ; pathology ; Brain Ischemia ; physiopathology ; Calcium-Transporting ATPases ; metabolism ; Energy Metabolism ; drug effects ; Male ; Mice ; Phosphocreatine ; metabolism ; Plants, Medicinal ; chemistry ; Random Allocation ; Salvia miltiorrhiza ; chemistry ; Sodium-Potassium-Exchanging ATPase ; metabolism ; Water ; metabolism

OBJECTIVETo investigate the effect of Shuangshen Ningxin (SSNX) formula on energy metabolism of myocardial ischemia/reperfusion rats.

METHODThe myocardial ischemia/reperfusion model of Wistar rats was established through the ligation of left anterior descending branch of coronary artery of for 40 min and the reperfusion for 2 h. The Wistar rats were randomly divided into six groups: the sham operation group, the model group, the Trimetazidine group (10 mg x kg(-1)) and SSNX groups (22.5, 45, 90 mg x kg(-1)). Preventive administration was conducted for 5 d. The operation was performed at 1 h on the day of the last administration. CK-MB assay kit was adopted to detect the activity of serum CK-MB. HPLC was used to determine ATP, ADP and AMP contents in myocardial tissues and calculate TAN and EC.

RESULTThe preventive administration with SSNX could reduce the activity of serum CK-MB and increase ATP content and EC level in myocardial tissues (P < 0.01 or P < 0.05 vs. the model group).

CONCLUSIONSSNX formula can maintain energy charge in cardiomyocytes and relieve ischemia/reperfusion injury by preserving ischemic myocardium ATP.

Adenosine Diphosphate ; metabolism ; Adenosine Monophosphate ; metabolism ; Animals ; Creatine Kinase, MB Form ; blood ; Drugs, Chinese Herbal ; administration & dosage ; Energy Metabolism ; drug effects ; Humans ; Male ; Myocardial Ischemia ; drug therapy ; metabolism ; surgery ; Myocardial Reperfusion ; Rats ; Rats, Wistar