Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Differential scanning calorimetry, optical spectroscopy, and activity measurements were used to investigate the effect of mannosylglycerate, a negatively charged osmolyte widely distributed among thermophilic and hyperthermophilic archaea and bacteria, on the thermal unfolding of ribonuclease A (RNase A). For comparison, assays in the presence of trehalose, a canonical solute in mesophiles, and potassium chloride were also carried out. A thermodynamic analysis was performed by using differential scanning calorimetry data. The changes in the heat capacity for unfolding were similar for the different solutes examined. Mannosylglycerate was an efficient thermostabiliser of RNase A and induced an increase of 6 degrees C mole(-1) in the melting temperature. Moreover, the performance of mannosylglycerate as a stabiliser depended on the net charge of the molecule, with the maximal effect being observed at pH values above 4.5. Analysis of the enthalpic and entropic contributions to unfolding, derived from calorimetric data, revealed that the stabilisation rendered by mannosylglycerate is primarily achieved through a decrease in the unfolding entropy. Also, the number of protons taken up by RNase A upon denaturation in the presence of mannosylglycerate was considerably higher than with other solutes, a result consistent with a more rigid structure of the native protein. Mannosylglycerate (potassium salt) inhibited the activity of RNase A, albeit to a smaller extent than KCl, and acted as an efficient suppressor of aggregation of the denatured protein, thereby having a remarkable beneficial effect on the inactivation of RNase A upon thermal denaturation. The results are discussed in view of the physiological role of this charged compatible solute.
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PMID:Protein stabilisation by compatible solutes: effect of mannosylglycerate on unfolding thermodynamics and activity of ribonuclease A. 1289 24

1. The reaction products of isoniazid with periodate-oxidized ribonucleosides and 5'-ribonucleotides have been characterized as the monohydrazones. 2. The stability, chromatographic and electrophoretic properties of the hydrazones are described. 3. (3)H-labelled isoniazid was shown to react with the 5'-linked terminal adenosine and cytidine groups of periodate-oxidized Escherichia coli transfer RNA. One mole of isoniazid reacts with 27x10(3)g. of the transfer RNA. 4. One mole of (3)H-labelled isoniazid reacts with approx. 10(6)g. of rabbit-reticulocyte ribosomal RNA. After fractionation of the RNA into its two components and treating the fractionated material with pancreatic ribonuclease and ribonuclease T(1) evidence is presented for the existence of two 5'-linked terminal sequences in the 30s fraction and only one sequence in the 17s fraction. 5. The application of this method to determining terminal sequences of high-molecular-weight RNA is discussed.
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PMID:TERMINAL-SEQUENCE STUDIES OF HIGH-MOLECULAR-WEIGHT RIBONUCLEIC. THE REACTION OF PERIODATE-OXIDIZED RIBONUCLEOSIDES , 5'-RIBONUCLEOTIDES AND RIBONUCLEIC ACID WITH ISONIAZID. 1434 Jan 6

In the present paper a procedure to calculate the properties of proteins in aqueous mixed solvents, particularly the excesses of the constituents of the mixed solvent near the protein molecule and the preferential binding parameters, is suggested. Expressions for the Kirkwood-Buff integrals in ternary mixtures and for the preferential binding parameter were derived and used to calculate various properties of infinitely dilute proteins in aqueous mixed solvents. The derived expressions and experimental information regarding the partial molar volumes and the preferential binding parameters were used to calculate the excesses (deficits) of water and cosolvent (in comparison with the bulk concentrations of protein-free mixed solvent) in the vicinity of ribonuclease A, ribonuclease T1, and lysozyme molecules. The calculations showed that water was in excess in the vicinity of ribonuclease A for water/glycerol and water/trehalose mixtures, and the cosolvent urea was in excess in the vicinity of ribonuclease T1 and lysozyme. The derivative of the activity coefficient of the protein with respect to the mole fraction of water was also calculated. This derivative was negative for the water/glycerol and water/trehalose mixed solvents and positive for the water/urea mixture. The mixture of lysozyme in the water/urea solvent is of particular interest, because the lysozyme at pH 7.0 is in its native state up to 9.3M urea, while at pH 2.0 it is denaturated between 2.5 and 5M and higher concentrations of urea. Our results demonstrated a striking similarity in the hydration of lysozyme at both pHs. It is worthwhile to note that the excesses of urea were only weakly composition dependent on both cases.
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PMID:A protein molecule in an aqueous mixed solvent: fluctuation theory outlook. 1610 95


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