Biophys J
Department of Medical Biochemistry and Genetics, Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA.
Published: December 2004
Ribonuclease Sa (RNase Sa) contains no tryptophan (Trp) residues. We have added single Trp residues to RNase Sa at sites where Trp is found in four other microbial ribonucleases, yielding the following variants of RNase Sa: Y52W, Y55W, T76W, and Y81W. We have determined crystal structures of T76W and Y81W at 1.1 and 1.0 A resolution, respectively. We have studied the fluorescence properties and stabilities of the four variants and compared them to wild-type RNase Sa and the other ribonucleases on which they were based. Our results should help others in selecting sites for adding Trp residues to proteins. The most interesting findings are: 1), Y52W is 2.9 kcal/mol less stable than RNase Sa and the fluorescence intensity emission maximum is blue-shifted to 309 nm. Only a Trp in azurin is blue-shifted to a greater extent (308 nm). This blue shift is considerably greater than observed for Trp71 in barnase, the Trp on which Y52W is based. 2), Y55W is 2.1 kcal/mol less stable than RNase Sa and the tryptophan fluorescence is almost completely quenched. In contrast, Trp59 in RNase T1, on which Y55W is based, has a 10-fold greater fluorescence emission intensity. 3), T76W is 0.7 kcal/mol more stable than RNase Sa, indicating that the Trp side chain has more favorable interactions with the protein than the threonine side chain. The fluorescence properties of folded Y76W are similar to those of the unfolded protein, showing that the tryptophan side chain in the folded protein is largely exposed to solvent. This is confirmed by the crystal structure of the T76W which shows that the side chain of the Trp is only approximately 7% buried. 4), Y81W is 0.4 kcal/mol less stable than RNase Sa. Based on the crystal structure of Y81W, the side chain of the Trp is 87% buried. Although all of the Trp side chains in the variants contribute to the unusual positive circular dichroism band observed near 235 nm for RNase Sa, the contribution is greatest for Y81W.
Download full-text PDF |
Source |
---|---|
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1304912 | PMC |
http://dx.doi.org/10.1529/biophysj.104.050377 | DOI Listing |
Acta Crystallogr F Struct Biol Commun
February 2025
Department of Chemistry `Ugo Schiff', Università degli Studi di Firenze, Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy.
Hen egg-white lysozyme (HEWL) is a small polycationic protein which is highly soluble and stable. This has led to it becoming a `molecular laboratory' where chemical biological operations and structural techniques are tested. To date, HEWL accounts for 1233 PDB entries, roughly 0.
View Article and Find Full Text PDFJ Phys Chem B
January 2025
Center for Ultrafast Science and Technology, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
Fermi resonance is a common phenomenon, and a hidden caveat exists in the applications of infrared probes, causing spectral complication and shorter vibrational lifetime. In this work, using the cyanotryptophan (CNTrp) side chain model compound 5-cyanoindole (CN-5CNI), we performed Fourier transform infrared spectroscopy (FTIR) and two-dimensional infrared (2D-IR) spectroscopy on unlabeled CN-5CNI and its isotopically labeled substituents (CN-5CNI, CN-5CNI, CN-5CNI) and demonstrated the existence of Fermi resonance in 5CNI. By constructing the Hamiltonian and simulating 2D-IR spectra, we show that the distinct Fermi resonance 2D-IR patterns in various isotope substituents are determined by the quantum mixing consequences at the = 1 state, as well as the = 2 state, where the Fermi coupling and anharmonicity play a crucial role.
View Article and Find Full Text PDFDes Monomers Polym
January 2025
Leibniz-Institut für Polymerforschung Dresden e.V, Dresden, Germany.
Enhancing both ionic conductivity and mechanical robustness remains a major challenge in designing solid-state electrolytes for lithium batteries. This work presents a novel approach in designing mechanically robust and highly conductive solid-state electrolytes, which involves ionic liquid-based cross-linked polymer networks incorporating polymeric ionic liquids (PILs). First, linear PILs with different side groups were synthesized for optimizing the structure.
View Article and Find Full Text PDFBiomater Sci
January 2025
Institute of Pharmacy, Freie Universität Berlin, 14195 Berlin, Germany.
We are facing a shortage of new antibiotics to fight against increasingly resistant bacteria. As an alternative to conventional small molecule antibiotics, antimicrobial polymers (AMPs) have great potential. These polymers contain cationic and hydrophobic groups and disrupt bacterial cell membranes through a combination of electrostatic and hydrophobic interactions.
View Article and Find Full Text PDFBiophys J
January 2025
Michael Sars Centre, University of Bergen, Norway. Electronic address:
Neuropeptides are inter-cellular signaling molecules occurring throughout animals. Most neuropeptides bind and activate G-protein coupled receptors, but some also activate ionotropic receptors (or "ligand-gated ion channels"). This is exemplified by the tetra-peptide H-Phe-Met-Arg-Phe-NH (FMRFa), which activates mollusc and annelid FMRFa-gated sodium channels (FaNaCs) from the trimeric degenerin/epithelial sodium channel superfamily.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!
© LitMetric 2025. All rights reserved.