In cultured chromaffin cells and plasma membrane vesicles from chromaffin tissue, the transport of D-[3H]adenosine followed Michaelis-Menten saturation kinetics, with Km values of 1.5 +/- 0.3 microM and 1.9 +/- 0.2 microM, respectively. The transport of the isomer, L-[3H]adenosine, showed sigmoidal kinetics in both preparations. In plasma membrane vesicles the S0.5 was 2.5 +/- 0.2 microM with a Hill coefficient of 2.8 and the Vmax value of 0.26 +/- 0.01 pmol s-1 (mg of protein)-1. In cultured chromaffin cells the kinetic parameters for L-[3H]adenosine were S0.5 = 6.2 +/- 0.2 microM and a Vmax 19.7 +/- 0.5 pmol/min per 10(6) cells, with a pronounced positive cooperativity. The Hill coefficient was 4.9. The transport of the L-isomer in cultured cells followed Michaelis-Menten kinetics at the lowest concentrations employed, below 2 microM. On the basis of these results, we propose a kinetic model whereby the adenosine transporter functions mnemonically.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1021/bi00214a020 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Sonochemical synthesis, optical properties and DFT studies on novel (N-arylamino)phenothiazinium dyes suitable for fluorescence cells imaging.
Spectrochim Acta A Mol Biomol Spectrosc
December 2024
Faculty of Chemistry and Chemical Engineering, Babeş-Bolyai University, 11 Arany Janos str., 400028 Cluj-Napoca, Romania. Electronic address:
Novel (N-arylamino)phenothiazinium dyes containing meta-substituted-arylamine auxochrome units were successfully obtained by applying a sonochemical protocol designed for a more efficient energy usage in the preparation of methylene blue (MB) analogues. Single crystal X-ray diffraction analysis revealed the spatial arrangement in aggregated crystalline state of (N-(meta-bromoaryl)amino)phenothiazinium dye with minor variances induced by the nature of the halogenide counterion (iodide or chloride). The optical UV-vis properties of the novel (N-arylamino)phenothiazinium dyes were comparable to those of the parent MB, with the longest wavelength absorption maxima situated in the visible range (640-680 nm), large molar extinction coefficients (log ε = 4.
View Article and Find Full Text PDFEnhancing the Bioavailability and Bioactivity of Curcumin for Disease Prevention and Treatment.
Antioxidants (Basel)
March 2024
Department of Biochemistry and Molecular Biology, Miller School of Medicine, University of Miami, Miami, FL 33136, USA.
Article Synopsis
- Curcumin, found in turmeric, is recognized for its potential health benefits, including anti-cancer and anti-inflammatory properties, but its absorption in the body may be too low to be effective.
- Dietary sources alone may not provide sufficient curcumin levels, leading researchers to explore methods to enhance its bioavailability, such as using nanoparticles.
- Increasing curcumin levels might boost its health benefits, particularly its antioxidant effects, but it also requires careful monitoring to avoid negative impacts on cellular functions.
Angiotensin I and II Stimulate Cell Invasion of SARS-CoV-2: Potential Mechanism via Inhibition of ACE2 Arm of RAS.
Physiol Res
March 2024
Institute of Experimental Endocrinology, Biomedical Research Center, Slovak Academy of Sciences, Bratislava, Slovak Republic. and Institute of Neuroimmunology, Slovak Academy of Sciences, Bratislava, Slovak Republic.
Angiotensin-converting enzyme 2 (ACE2), one of the key enzymes of the renin-angiotensin system (RAS), plays an important role in SARS-CoV-2 infection by functioning as a virus receptor. Angiotensin peptides Ang I and Ang II, the substrates of ACE2, can modulate the binding of SARS-CoV-2 Spike protein to the ACE2 receptor. In the present work, we found that co incubation of HEK-ACE2 and Vero E6 cells with the SARS-CoV-2 Spike pseudovirus (PVP) resulted in stimulation of the virus entry at low and high micromolar concentrations of Ang I and Ang II, respectively.
View Article and Find Full Text PDFDifferential superoxide production in phosphorylated neuronal nitric oxide synthase mu and alpha variants.
J Inorg Biochem
February 2024
College of Pharmacy, University of New Mexico, Albuquerque, NM 87131, USA; Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, NM 87131, USA. Electronic address:
Neuronal nitric oxide synthase (nNOS) is regulated by phosphorylation in vivo, yet the underlying biochemical mechanisms remain unclear, primarily due to difficulty in obtaining milligram quantities of phosphorylated nNOS protein; detailed spectroscopic and rapid kinetics investigations require purified protein samples at a concentration in the range of hundreds microM. Moreover, the functional diversity of the nNOS isoform is linked to its splice variants. Also of note is that determination of protein phosphorylation stoichiometry remains as a challenge.
View Article and Find Full Text PDFCytotoxic effect of 13α-estrane derivatives on breast, endometrial and ovarian cancer cell lines.
J Steroid Biochem Mol Biol
September 2023
Institute of Biochemistry and Molecular Genetics, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia. Electronic address:
Hormone-dependent cancers such as breast, uterine, and ovarian cancers account for more than 35% of all cancers in women. Worldwide, these cancers occur in more than 2.7 million women/year and account for 22% of cancer-related deaths/year.
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!