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

N⁶-methyladenosine (m⁶A) exists widely in eukaryotes as a post-transcriptional modification. This modification is dynamically and reversibly regulated by methyltransferases and demethylases, and is involved in regulating biological effects through m⁶A binding proteins. Recent studies have elucidated that m⁶A is involved in embryonic skin morphogenesis, wound repair, and pathophysiological processes such as inflammatory response, angiogenesis, and fibrosis. This review summarizes the role of m⁶A and its related proteins in the related pathophysiological processes of wound repair, so as to provide a new theoretical basis for the treatment strategy of wound repair.
RNA/metabolism* ; Methylation ; Adenosine/metabolism* ; Methyltransferases/metabolism*

There are more than 150 types of chemical modifications in RNA, mainly methylation, which are widely distributed in all kinds of RNA, including messenger RNA, transfer RNA, ribosomal RNA, non-coding small RNA and long non-coding RNA. In recent years, the identification of RNA methylation modification enzymes and the development of high-throughput sequencing technology at transcriptome level laid a foundation for revealing the expression and function of genes regulated by chemical modification of RNA. In this review, the most recent advances of RNA methylation, especially N6-methyladenosine (m
Adenosine/metabolism* ; Hematopoiesis ; Humans ; Methylation ; RNA/metabolism*

Adenosine ; metabolism ; Adenosine Kinase ; metabolism ; Adenosine Triphosphate ; metabolism ; Animals ; Brain ; drug effects ; metabolism ; Diet, Carbohydrate-Restricted ; methods ; Diet, Ketogenic ; Energy Metabolism ; Epilepsy ; diet therapy ; metabolism ; Humans

RNA methylation is of great significance in the regulation of gene expression, among which the more important methylation modifiers are N6-methyladenosine (m6A) and 5-methylcytosine (m5C). The methylation process is mainly regulated by 3 kinds of proteins: methyltransferase, demethylase, and reader. m6A, m5C, and their related proteins have high abundance in the brain, and they have important roles in the development of the nervous system and the repair and remodeling of the vascular system. The neurovascular unit (NVU) is a unit of brain structure and function composed of neurons, capillaries, astrocytes, supporting cells, and extracellular matrix. The local microenvironment for NVU has an important role in nerve cell function repair, and the remodeling of NVU is of great significance in the prognosis of various neurological diseases.
5-Methylcytosine ; Adenosine/metabolism* ; Methylation ; Methyltransferases/metabolism* ; RNA

Adenosine Triphosphate ; Mouth ; metabolism ; Receptors, Purinergic P2X ; metabolism

Adenosine is a metabolite produced abundantly in the tumor microenvironment, dampening immune response in inflamed tissues via adenosine A2A receptor (A2AR) which is widely expressed on immune cells, inhibiting anti-tumor immune response accordingly. Therefore, blocking adenosine signaling pathway is of potential to promote anti-tumor immunity. This review briefly introduces adenosine signaling pathway, describes its role in regulating tumor immunity and highlights A2AR blockade in cancer therapy. Prospective anti-tumor activity of adenosine/A2AR inhibition has been revealed by preclinical data, and a number of clinical trials of A2AR antagonists are under way. Primary results from clinical trials suggest that A2AR antagonists are well tolerated in cancer patients and are effective both as monotherapy and in combination with other therapies. In the future, finding predictive biomarkers are critical to identify patients most likely to benefit from adenosine pathway blockade, and further researches are needed to rationally combine A2AR antagonists with other anti-tumor therapies.
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Adenosine/therapeutic use* ; Adenosine A2 Receptor Antagonists/therapeutic use* ; Humans ; Lung Neoplasms ; Receptor, Adenosine A2A/metabolism* ; Tumor Microenvironment

BACKGROUND: ADA is an enzyme found in most cells, and is involved in purine metabolism, but its chief role concerns the proliferation and differentiation of lymphocytes, especially T-lymphocytes. For that reason ADA has been looked on as a marker of cell-mediate immunity, which is th key mechanism of the tuberculous pleural effusion. Thus, the pleural fluid ADA activity is increased in the tuberculous pleural effusion.Age associated immune deline is characterized by decreases in both B and T-lymphocyte function and the former may be largely a result of the latter. Therefore, the epleural fluid ADA activity would be lower in old rather than in young, patients with tuberculous pleural effusion. We studied the relationship between age, and pleural fluid ADA activity, in patients with tuberculous pleural effusion. METHODS: In the 46 patients with tuberculous pleural effusion enroll in this study, the pleural fluid ADA activities were measured by means of an automated kinetic method. RESULTS: The mean age of the patients was 53.0+/-22.0 years, with a male to female ratio of 30 : 16. The patients were divided into two groups, young patients, regarded as <65 and old regarded as >or=65 years with 28 and 18 patients, respectively. The pleural fluid ADA activity in both groups show significant differences : 99.4+/- 22.6 IU/L(young patients) Vs. 75.8+/-30.9 IU/L(old patients)(p<0.05), but a negative correlation with age (r=-0.311, p<0.05). CONCLUSION: Although pleural fluid ADA activity was not adequately increase, tuberculous pleural effusion, in older patients, would have to be considered clinically suspicious tuberculous pleural effusion.
Adenosine Deaminase* ; Adenosine* ; Female ; Humans ; Lymphocytes ; Male ; Metabolism ; Pleural Effusion* ; T-Lymphocytes

BACKGROUND: ADA is an enzyme found in most cells, and is involved in purine metabolism, but its chief role concerns the proliferation and differentiation of lymphocytes, especially T-lymphocytes. For that reason ADA has been looked on as a marker of cell-mediate immunity, which is th key mechanism of the tuberculous pleural effusion. Thus, the pleural fluid ADA activity is increased in the tuberculous pleural effusion.Age associated immune deline is characterized by decreases in both B and T-lymphocyte function and the former may be largely a result of the latter. Therefore, the epleural fluid ADA activity would be lower in old rather than in young, patients with tuberculous pleural effusion. We studied the relationship between age, and pleural fluid ADA activity, in patients with tuberculous pleural effusion. METHODS: In the 46 patients with tuberculous pleural effusion enroll in this study, the pleural fluid ADA activities were measured by means of an automated kinetic method. RESULTS: The mean age of the patients was 53.0+/-22.0 years, with a male to female ratio of 30 : 16. The patients were divided into two groups, young patients, regarded as <65 and old regarded as >or=65 years with 28 and 18 patients, respectively. The pleural fluid ADA activity in both groups show significant differences : 99.4+/- 22.6 IU/L(young patients) Vs. 75.8+/-30.9 IU/L(old patients)(p<0.05), but a negative correlation with age (r=-0.311, p<0.05). CONCLUSION: Although pleural fluid ADA activity was not adequately increase, tuberculous pleural effusion, in older patients, would have to be considered clinically suspicious tuberculous pleural effusion.
Adenosine Deaminase* ; Adenosine* ; Female ; Humans ; Lymphocytes ; Male ; Metabolism ; Pleural Effusion* ; T-Lymphocytes

Objective To observe the effect of excess oxygen supply for different time periods on the mitochondrial energy metabolism in alveolar epithelial type Ⅱ cells. Methods Rat RLE-6TN cells were assigned into a control group (21% O₂ for 4 h) and excess oxygen supply groups (95% O₂ for 1,2,3,and 4 h,res-pectively).The content of adenosine triphosphate (ATP),the activity of mitochondrial respiratory chain complex V,and the mitochondrial membrane potential were determined by luciferase assay,micro-assay,and fluorescent probe JC-1,respectively.Real-time fluorescence quantitative PCR was employed to determine the mRNA levels of NADH dehydrogenase subunit 1 (ND1),cytochrome b (Cytb),cytochrome C oxidase subunit I (COXI),and adenosine triphosphatase 6 (ATPase6) in the core subunits of mitochondrial respiratory chain complexes Ⅰ,Ⅲ,Ⅳ,and Ⅴ,respectively. Results Compared with the control group,excess oxygen supply for 1,2,3,and 4 h down-regulated the mRNA levels of ND1 (q=24.800,P<0.001;q=13.650,P<0.001;q=9.869,P<0.001;q=20.700,P<0.001),COXI (q=16.750,P<0.001;q=10.120,P<0.001;q=8.476,P<0.001;q=14.060,P<0.001),and ATPase6 (q=22.770,P<0.001;q=15.540,P<0.001;q=12.870,P<0.001;q=18.160,P<0.001).Moreover,excess oxygen supply for 1 h and 4 h decreased the ATPase activity (q=9.435,P<0.001;q=11.230,P<0.001) and ATP content (q=5.615,P=0.007;q=5.029,P=0.005).The excess oxygen supply for 2 h and 3 h did not cause significant changes in ATPase activity (q=0.156,P=0.914;q=3.197,P=0.116) and ATP content (q=0.859,P=0.557;q=1.273,P=0.652).There was no significant difference in mitochondrial membrane potential among the groups (F=0.303,P=0.869). Conclusion Short-term excess oxygen supply down-regulates the expression of the core subunits of mitochondrial respiratory chain complexes and reduces the activity of ATPase,leading to the energy metabolism disorder of alveolar epithelial type Ⅱ cells.
Animals ; Rats ; Energy Metabolism ; Adenosine Triphosphate ; Adenosine Triphosphatases ; RNA, Messenger ; Oxygen