The activities of N-acetylneuraminate 9-phosphate synthase and N-acetylneuraminate 9-phosphatase, the two enzymes involved in the final steps of the biosynthetic pathway of N-acetylneuraminic acid, were measured with the substrates N-acetyl[14C]mannosamine 6-phosphate and N-acetyl[14C]neuraminic acid 9-phosphate respectively. Subcellular localization studies in rat liver indicated that both enzymes are localized in the cytosolic fraction after homogenization in sucrose medium. To test the possibility of misinterpretation due to the hydrolysis of N-acetylneuraminic acid 9-phosphate by non-specific phosphatases, the hydrolysis of various phosphate esters by the cytosolic fraction was tested. Only p-nitrophenyl phosphate was hydrolysed; however, competition studies with N-acetylneuraminic acid 9-phosphate and p-nitrophenyl phosphate indicated that two different enzymes were involved and that no competition existed between the two substrates. In various other rat tissues N-acetylneuraminate-9-phosphate synthase and N-acetylneuraminate 9-phosphatase activities were detected, suggesting that N-acetylmannosamine 6-phosphate is a general precursor for N-acetylneuraminic acid biosynthesis in all the tissues studied.
Download full-text PDF |
Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1144303 | PMC |
| http://dx.doi.org/10.1042/bj2230323 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Hepatotoxic effects of environmentally relevant concentrations of polystyrene microplastics on senescent Zebrafish (Danio rerio): Patterns of stress response and metabolomic alterations.
Aquat Toxicol
January 2025
College of Animal Science and Technology, Henan University of Science and Technology, Luoyang, Henan 471003, China. Electronic address:
The hepatotoxicity of microplastics (MPs) has garnered increasing attention, but their effects on elderly organisms remain inadequately characterized, particularly concerning hepatic stress response patterns in environmental conditions. In this study, a 10-day exposure period of elderly zebrafish to polystyrene microplastics (PS-MPs, 1 µm) was conducted, with exposure concentrations set at 5.6 × 10 µg/L, 5.
View Article and Find Full Text PDFN-acetylneuraminic acid promotes ferroptosis of H9C2 cardiomyocytes with hypoxia/reoxygenation injury by inhibiting the Nrf2 axis.
Nan Fang Yi Ke Da Xue Xue Bao
January 2025
Department of Cardiovascular Diseases, First Affiliated Hospital of Bengbu Medical University, Bengbu 233000, China.
Objectives: To investigate the mechanism through which N-acetylneuraminic acid (Neu5Ac) exacerbates hypoxia/reoxygenation (H/R) injury in rat cardiomyocytes (H9C2 cells).
Methods: H9C2 cells were cultured in hypoxia and glucose deprivation for 8 h followed by reoxygenation for different durations to determine the optimal reoxygenation time. Under the optimal H/R protocol, the cells were treated with 0, 5, 10, 20, 30, 40, 50, and 60 mmol/L Neu5Ac during reoxygenation to explore the optimal drug concentration.
N-acetylated sugars in clownfish and damselfish skin mucus as messengers involved in chemical recognition by anemone host.
Sci Rep
January 2025
Department of Computational Biology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.
The clownfish - sea anemone system is a great example of symbiotic mutualism where host «toxicity» does not impact its symbiont partner, although the underlying protection mechanism remains unclear. The regulation of nematocyst discharge in cnidarians involves N-acetylated sugars like sialic acid, that bind chemoreceptors on the tentacles of sea anemones, leading to the release of stings. It has been suggested that clownfish could be deprived of sialic acid on their skin surface, sparing them from being stung and facilitating mutualism with sea anemones.
View Article and Find Full Text PDFAn RNase III-processed sRNA coordinates sialic acid metabolism of during gut colonization.
Proc Natl Acad Sci U S A
January 2025
Key Laboratory of Medical Molecular Virology (Ministry of Education / National Health Commission / Chinese Academy of Medical Sciences), Shanghai Frontiers Science Center of Pathogenic Microorganisms and Infection, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200033, China.
Sialic acids derived from colonic mucin glycans are crucial nutrients for enteric bacterial pathogens like . The uptake and utilization of sialic acid in depend on coordinated regulons, each activated by specific metabolites at the transcriptional level. However, the mechanisms enabling crosstalk among these regulatory circuits to synchronize gene expression remain poorly understood.
View Article and Find Full Text PDFDestabilization of Glycosyl Cation by an Electron-Withdrawing Substituent at C-5 Makes Sialylation Reaction More α-Stereoselective.
J Org Chem
January 2025
N.D. Zelinsky Institute of Organic Chemistry of the Russian Academy of Sciences, Leninsky prosp. 47, Moscow 119991, Russian Federation.
Comparison of the reactivity of sialyl chlorides and bromides based on -acetylneuraminic acid (Neu5Ac) and its deaminated analogue (KDN) in reactions with MeOH and -PrOH without a promoter revealed that the acetoxy group at C-5 in a molecule of a sialic acid glycosyl donor can destabilize the corresponding glycosyl cation making the S1-like reaction pathway unfavorable. A change to the S2-like reaction pathway ensures preferential formation of the α-glycoside.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!