Biomaterial Database

Multistage unfolding of wheat germ ribosomal 5S RNA analyzed by differential scanning calorimetry. 1985

S J Li, and A G Marshall

Unfolding of purified wheat germ ribosomal RNA has been studied by differential scanning calorimetry (DSC) from 15 to 95 degrees C, in the presence and absence of 100 mM NaCl and/or 10 mM MgCl2. The total enthalpy of melting varies from about 290 (no sodium or magnesium) to 480 kcal/mol (Mg2+ only) and precisely accounts for the number and types of base pairs deduced from prior Fourier-transform infrared experiments. The composite DSC curves are analyzed into four individual two-state melting stages. Both Na+ and Mg2+ shift the melting transitions to higher temperature; in addition, Mg2+ causes the individual transitions to merge (i.e., melt cooperatively) and leads to irreversible chain cleavage at high temperature. The results are analyzed according to three general secondary base-pairing models for eukaryotic 5S RNA.

UI	MeSH Term	Description	Entries
D008274	Magnesium	A metallic element that has the atomic symbol Mg, atomic number 12, and atomic weight 24.31. It is important for the activity of many enzymes, especially those involved in OXIDATIVE PHOSPHORYLATION.
D008970	Molecular Weight	The sum of the weight of all the atoms in a molecule.	Molecular Weights,Weight, Molecular,Weights, Molecular
D009690	Nucleic Acid Conformation	The spatial arrangement of the atoms of a nucleic acid or polynucleotide that results in its characteristic 3-dimensional shape.	DNA Conformation,RNA Conformation,Conformation, DNA,Conformation, Nucleic Acid,Conformation, RNA,Conformations, DNA,Conformations, Nucleic Acid,Conformations, RNA,DNA Conformations,Nucleic Acid Conformations,RNA Conformations
D009691	Nucleic Acid Denaturation	Disruption of the secondary structure of nucleic acids by heat, extreme pH or chemical treatment. Double strand DNA is "melted" by dissociation of the non-covalent hydrogen bonds and hydrophobic interactions. Denatured DNA appears to be a single-stranded flexible structure. The effects of denaturation on RNA are similar though less pronounced and largely reversible.	DNA Denaturation,DNA Melting,RNA Denaturation,Acid Denaturation, Nucleic,Denaturation, DNA,Denaturation, Nucleic Acid,Denaturation, RNA,Nucleic Acid Denaturations
D002152	Calorimetry, Differential Scanning	Differential thermal analysis in which the sample compartment of the apparatus is a differential calorimeter, allowing an exact measure of the heat of transition independent of the specific heat, thermal conductivity, and other variables of the sample.	Differential Thermal Analysis, Calorimetric,Calorimetric Differential Thermal Analysis,Differential Scanning Calorimetry,Scanning Calorimetry, Differential
D001483	Base Sequence	The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.	DNA Sequence,Nucleotide Sequence,RNA Sequence,DNA Sequences,Base Sequences,Nucleotide Sequences,RNA Sequences,Sequence, Base,Sequence, DNA,Sequence, Nucleotide,Sequence, RNA,Sequences, Base,Sequences, DNA,Sequences, Nucleotide,Sequences, RNA
D012335	RNA, Ribosomal	The most abundant form of RNA. Together with proteins, it forms the ribosomes, playing a structural role and also a role in ribosomal binding of mRNA and tRNAs. Individual chains are conventionally designated by their sedimentation coefficients. In eukaryotes, four large chains exist, synthesized in the nucleolus and constituting about 50% of the ribosome. (Dorland, 28th ed)	Ribosomal RNA,15S RNA,RNA, 15S
D012639	Seeds	The encapsulated embryos of flowering plants. They are used as is or for animal feed because of the high content of concentrated nutrients like starches, proteins, and fats. Rapeseed, cottonseed, and sunflower seed are also produced for the oils (fats) they yield.	Diaspores,Elaiosomes,Embryos, Plant,Plant Embryos,Plant Zygotes,Zygotes, Plant,Diaspore,Elaiosome,Embryo, Plant,Plant Embryo,Plant Zygote,Seed,Zygote, Plant
D012965	Sodium Chloride	A ubiquitous sodium salt that is commonly used to season food.	Sodium Chloride, (22)Na,Sodium Chloride, (24)NaCl
D013816	Thermodynamics	A rigorously mathematical analysis of energy relationships (heat, work, temperature, and equilibrium). It describes systems whose states are determined by thermal parameters, such as temperature, in addition to mechanical and electromagnetic parameters. (From Hawley's Condensed Chemical Dictionary, 12th ed)	Thermodynamic