Earlier studies by others had indicated that actinomycin D (ACTD) binds well to d(AACCATAG) and the end sequence TAG-3' is essential for its strong binding. In an effort to verify these assertions and to uncover other possible strong ACTD binding sequences as well as to elucidate the nature of their binding, systematic studies have been carried out with oligomers of d(AACCAXYG) sequence motifs, where X and Y can be any DNA base. The results indicate that in addition to TAG-3', oligomers ending with XAG-3' and XCG-3' all provide binding constants > or =1 x 10(7) M(-1) and even sequences ending with XTG-3' and XGG-3' exhibit binding affinities in the range 1-8 x 10(6) M(-1). The nature of the strong ACTD affinity of the sequences d(A1A2C3C4A5X6Y7G8) was delineated via comparative binding studies of d(AACCAAAG), d(AGCCAAAG) and their base substituted derivatives. Two binding modes are proposed to coexist, with the major component consisting of the 3'-terminus G base folding back to base pair with C4 and the ACTD inserting at A2C3C4 by looping out the C3 while both faces of the chromophore are stacked by A and G bases, respectively. The minor mode is for the G to base pair with C3 and to have the same A/chromophore/G stacking but without a looped out base. These assertions are supported by induced circular dichroic and fluorescence spectral measurements.
Download full-text PDF |
Source |
---|---|
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC373288 | PMC |
http://dx.doi.org/10.1093/nar/gkh178 | DOI Listing |
Water Res
January 2025
State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing, Jiangsu 210023, China. Electronic address:
To address the challenge of antibiotic-containing wastewater, a novel micromagnetic carrier-modified integrated fixed-film activated sludge system (MC-IFAS) was developed for treating tetracycline (TC)-containing swine wastewater in this study. The magnetic effects of the MC significantly enhanced TC removal by improving TC biosorption and biodegradation in both the suspended activated sludge and the carrier-attached biofilm in the MC-IFAS. The increased electrostatic attraction and number of binding sites in both the activated sludge and the biofilm enhanced their TC biosorption capacities, particularly in the activated sludge.
View Article and Find Full Text PDFInorg Chem
January 2025
Department of Chemistry University of Tennessee, Knoxville, Tennessee 37996-1600, United States.
A series of 2-pyridone[α]-fused BOPHYs - were prepared via a two-step procedure involving the preparation of enamine, followed by an intramolecular heterocyclization reaction. In addition to being fully conjugated with the BOPHY core pyridone fragment, BOPHYs and have a pyridine group connected to the BOPHY core via one- or two -CH- groups. New BOPHYs were characterized by spectroscopy as well as X-ray diffraction.
View Article and Find Full Text PDFBiochemistry
January 2025
Department of Chemistry, University of California, Berkeley, California 94720, United States.
In many bacteria, the location of the mRNA start codon is determined by a short ribosome binding site sequence that base pairs with the 3'-end of 16S rRNA (rRNA) in the 30S subunit. Many groups have changed these short sequences, termed the Shine-Dalgarno (SD) sequence in the mRNA and the anti-Shine-Dalgarno (ASD) sequence in 16S rRNA, to create "orthogonal" ribosomes to enable the synthesis of orthogonal polymers in the presence of the endogenous translation machinery. However, orthogonal ribosomes are prone to SD-independent translation.
View Article and Find Full Text PDFChem Biodivers
January 2025
Universidad Nacional del Litoral Facultad de Bioquimica y Ciencias Biologicas, Química Orgánica, Ciudad Universitaria. Paraje el Pozo S/N, Argentina, 3000, Santa Fe, ARGENTINA.
The COVID-19 pandemic, caused by the SARS-CoV-2 virus, has highlighted the urgent need for novel therapeutic agents targeting viral enzymes such as the main protease (Mpro), which plays a crucial role in viral replication. In this study, we investigate the inhibitory potential of 23 peptides isolated from the skin of amphibians belonging to the Hylidae and Leptodactylidae families against SARS-CoV-2 Mpro. Five peptides demonstrated significant inhibition using a colorimetric Mpro inhibition assay, with IC50 values ranging from 41 to 203 µM.
View Article and Find Full Text PDFACS Nano
January 2025
Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117585, Singapore.
Metal nanoclusters (NCs), owing to their atomic precision and unique molecule-like properties, have gained widespread attention for applications ranging from catalysis to bioimaging. In recent years, proteins, with their hierarchical structures and diverse functionalities, have emerged as good candidates for functionalizing metal NCs, rendering metal NC-protein conjugates with combined and even synergistically enhanced properties featured by both components. In this Perspective, we explore key questions regarding why proteins serve as complementary partners for metal NCs, the methodologies available for conjugating proteins with metal NCs, and the characterization techniques necessary to elucidate the structures and interactions within this emerging bionano system.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!