Biomaterial Database

The solubilities of five cyclic dipeptides in water and in aqueous urea at 298.15 K: a quantitative model for the denaturation of proteins in aqueous urea solutions. 1994

A H Sijpkes, and G J van de Kleut, and S C Gill

Department of Chemistry and Biochemistry, University of Colorado at Boulder 80309-0215.

The solubilities of cyclo(L-alanylglycine), cyclo(L-alanyl-L-alanine), cyclo(glycyl-L-leucine), cyclo(L-valyl-L-valine) and cyclo(glycyl-L-phenylalanine) were determined in water and in aqueous urea solutions up to concentrations of 9 molar urea at 298.15 K. The solubilities of all cyclic dipeptides increase with increasing urea concentration. A simple equilibrium model, taking into account the activity of urea and that of water, fits the solubility data yielding apparent equilibrium constants describing the interactions occurring between urea and the peptide groups plus the alkyl groups that are next to these peptide groups. The apparent equilibrium constants were converted to Gibbs energy parameters for each amino acid residue which were then used to make a quantitative estimate of the contribution of urea to the denaturation of proteins.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008954	Models, Biological	Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.	Biological Model,Biological Models,Model, Biological,Models, Biologic,Biologic Model,Biologic Models,Model, Biologic
D010456	Peptides, Cyclic	Peptides whose amino acid residues are linked together forming a circular chain. Some of them are ANTI-INFECTIVE AGENTS; some are biosynthesized non-ribosomally (PEPTIDE BIOSYNTHESIS, NON-RIBOSOMAL).	Circular Peptide,Cyclic Peptide,Cyclic Peptides,Cyclopeptide,Orbitide,Circular Peptides,Cyclopeptides,Orbitides,Peptide, Circular,Peptide, Cyclic,Peptides, Circular
D011489	Protein Denaturation	Disruption of the non-covalent bonds and/or disulfide bonds responsible for maintaining the three-dimensional shape and activity of the native protein.	Denaturation, Protein,Denaturations, Protein,Protein Denaturations
D002627	Chemistry, Physical	The study of CHEMICAL PHENOMENA and processes in terms of the underlying PHYSICAL PHENOMENA and processes.	Physical Chemistry,Chemistries, Physical,Physical Chemistries
D004151	Dipeptides	Peptides composed of two amino acid units.	Dipeptide
D012995	Solubility	The ability of a substance to be dissolved, i.e. to form a solution with another substance. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)	Solubilities
D012996	Solutions	The homogeneous mixtures formed by the mixing of a solid, liquid, or gaseous substance (solute) with a liquid (the solvent), from which the dissolved substances can be recovered by physical processes. (From Grant & Hackh's Chemical Dictionary, 5th ed)	Solution
D014508	Urea	A compound formed in the liver from ammonia produced by the deamination of amino acids. It is the principal end product of protein catabolism and constitutes about one half of the total urinary solids.	Basodexan,Carbamide,Carmol
D014867	Water	A clear, odorless, tasteless liquid that is essential for most animal and plant life and is an excellent solvent for many substances. The chemical formula is hydrogen oxide (H2O). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Hydrogen Oxide