scholarly journals Structural features responsible for kinetic thermal stability of a carboxypeptidase from the archaebacterium Sulfolobus solfataricus

1993 ◽  
Vol 295 (3) ◽  
pp. 827-831 ◽  
Author(s):  
A Villa ◽  
L Zecca ◽  
P Fusi ◽  
S Colombo ◽  
G Tedeschi ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Thermal Inactivation ◽  
Metal Removal ◽  
Hydrophobic Interactions ◽  
Sulfolobus Solfataricus ◽  
Structural Features ◽  
Inactivation Rate ◽  
Salt Bridges ◽  
Native Conformation ◽  
Thermal Stability Of

Investigations were performed on the structural features responsible for kinetic thermal stability of a thermostable carboxypeptidase from the thermoacidophilic archaebacterium Sulfolobus solfataricus which had been purified previously and identified as a zinc metalloprotease [Colombo, D'Auria, Fusi, Zecca, Raia and Tortora (1992) Eur. J. Biochem. 206, 349-357]. Removal of Zn2+ by dialysis led to reversible activity loss, which was promptly restored by addition of 80 microM ZnCl2 to the assay mixture. For the first-order irreversible thermal inactivation the metal-depleted enzyme showed an activation energy value of 205.6 kJ.mol-1, which is considerably lower than that of the holoenzyme (494.4 kJ.mol-1). The values of activation free energies, enthalpies and entropies also dropped with metal removal. Thermal inactivation of the apoenzyme was very quick at 80 degrees C, whereas the holoenzyme was stable at the same temperature. These findings suggest a major stabilizing role for the bivalent cation. Chaotropic salts strongly destabilized the holoenzyme, showing that hydrophobic interactions are involved in maintaining the native conformation of the enzyme. However, the inactivation rate was also increased by sodium sulphate, acetate and chloride, which are not chaotropes, indicating that one or more salt bridges concur in stabilizing the active enzyme. Furthermore, at the extremes of the pH-stability curve, NaCl did not affect the inactivation rate, confirming the stabilizing role of intramolecular ionic bonds, as a pH-dependent decrease in stability is likely to occur from breaking of salt bridges involved in maintaining the native conformation of the protein.

scholarly journals Further thermal characterization of an aspartate aminotransferase from a halophilic organism

1994 ◽  
Vol 298 (2) ◽  
pp. 465-470 ◽  
Author(s):  
F J G Muriana ◽  
M C Alvarez-Ossorio ◽  
A M Relimpio
Keyword(s):  
Thermal Stability ◽  
Aspartate Aminotransferase ◽  
Thermal Inactivation ◽  
Hydrophobic Interactions ◽  
Thermal Characterization ◽  
Haloferax Mediterranei ◽  
First Order Kinetics ◽  
Effects Of Temperature ◽  
Thermal Stability Of

Aspartate aminotransferase (AspAT, EC 2.6.1.1) from the halophilic archaebacterium Haloferax mediterranei was purified [Muriana, Alvarez-Ossorio and Relimpio (1991) Biochem. J. 278, 149-154] and further characterization of the effects of temperature on the activity and stability of the halophilic AspAT were carried out. The halophilic transaminase is most active at 65 degrees C and stable at high temperatures, under physiological or nearly physiological conditions (3.5 M KCl, pH 7.8). Thermal inactivation (60-85 degrees C) of the halophilic AspAT followed first-order kinetics, 2-oxoglutarate causing a shift of the thermal inactivation curves to higher temperatures. The salt concentration affected the thermal stability of the halophilic transaminase at 60 degrees C, suggesting that disruption of hydrophobic interactions may play an important role in the decreased thermal stability of the enzyme.

Thermal stability of the structural features in the superhydrophobic boehmite films on austenitic stainless steels

2008 ◽  
Vol 254 (16) ◽  
pp. 5129-5133 ◽  
Author(s):  
Xiaoxue Zhang ◽  
Mari Honkanen ◽  
Mikael Järn ◽  
Jouko Peltonen ◽  
Viljami Pore ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Structural Features ◽  
Thermal Stability Of

Structural Features and Thermal Stability of 25,26,27,28-Tetrahydroxycalix[4]arene Molecular Complexes with Solvents

2013 ◽  
Vol 118 (1) ◽  
pp. 338-345 ◽  
Author(s):  
Oleg V. Surov ◽  
Marina I. Voronova ◽  
Vladimir P. Barannikov ◽  
Gennady P. Shaposhnikov
Keyword(s):  
Thermal Stability ◽  
Molecular Complexes ◽  
Structural Features ◽  
Thermal Stability Of

Conservation of Amino Acids into Multiple Alignments Involved in Pairwise Interactions in Three-Dimensional Protein Structures

2003 ◽  
Vol 01 (03) ◽  
pp. 505-520 ◽  
Author(s):  
Mounir Errami ◽  
Christophe Geourjon ◽  
Gilbert Deléage
Keyword(s):  
Amino Acids ◽  
Disulfide Bonds ◽  
Hydrophobic Interactions ◽  
Protein Structures ◽  
Three Dimensional ◽  
Structural Features ◽  
Multiple Alignment ◽  
Salt Bridges ◽  
Multiple Alignments ◽  
Multiple Sequences

We present an original strategy, that involves a bioinformatic software structure, in order to perform an exhaustive and objective statistical analysis of three-dimensional structures of proteins. We establish the relationship between multiple sequences alignments and various structural features of proteins. We show that amino acids implied in disulfide bonds, salt bridges and hydrophobic interactions are particularly conserved. Effects of identity, global similarity within alignments, and accessibility of interactions have been studied. Furthermore, we point out that the more variable the sequences within a multiple alignment, the more informative the multiple alignment. The results support multiple alignments usefulness for predictions of structural features.

Thermal Stability of Rapidly Solidified Alloys of Aluminium with Transition Metals

2006 ◽  
Vol 519-521 ◽  
pp. 389-394 ◽  
Author(s):  
Dalibor Vojtěch ◽  
Jan Verner ◽  
Barbora Bártová ◽  
Karel Saksl
Keyword(s):  
Thermal Stability ◽  
Transition Metals ◽  
Solid Solutions ◽  
Melt Spinning ◽  
Structural Features ◽  
High Thermal Stability ◽  
Crystalline Phases ◽  
Supersaturated Solid Solutions ◽  
Rapidly Solidified ◽  
Thermal Stability Of

Rapidly solidified (RS) Al-TM (TM = transition metal) alloys are perspective materials from scientific, as well as technological point of view. Generally, they are produced by the melt atomization or by the melt spinning. Subsequent compaction is commonly performed by the hot extrusion. Since transition metals, such as Cr, Fe, Ni, Zr, Ti, Mn and others, have low diffusion coefficients in solid aluminium (lower by several orders of magnitude than those of common alloying elements like Cu, Si, Mg, Zn etc.) the RS Al-TM alloys are characterized by a high thermal stability. In this paper, several RS Al-TM (TM = Cr, Fe, Ti, Mn, Ni) alloys prepared by the melt spinning and melt atomization are compared to commercially available 2xxx, 6xxx and 7xxx wrought alloys. The main structural features of both RS and wrought alloys are described. The RS alloys are characterized by the presence of micro and nano-scale crystalline and/or quasi-crystalline phases and supersaturated solid solutions. The elevated-temperature behaviour is compared for both groups of materials. The thermal stability of the investigated materials is determined by room temperature hardness measurements after various annealing regimes and a high thermal stability of the RS alloys is demonstrated. The microstructural changes and phase transformations occurring in the investigated materials upon heating are described. In the Al-TM alloys, very slow decomposition of the supersaturated solid solutions, precipitation and decomposition of the metastable quasi-crystalline phases occur.

Thermal stability tuning without affecting gas-binding function of Thermochromatium tepidum cytochrome c'

2021 ◽  
Author(s):  
Sotaro Fujii ◽  
Satoru Kobayashi ◽  
Taisuke Yoshimi ◽  
Yuji Kobayashi ◽  
Satoshi Wakai ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Amino Acid ◽  
Hydrophobic Interactions ◽  
Carbon Oxide ◽  
Stability Range ◽  
Structure Comparison ◽  
Binding Function ◽  
Cytochromes C ◽  
Sensor Proteins ◽  
Thermal Stability Of

Abstract Hydrogenophilus thermoluteolus, Thermochromatium tepidum, and Allochromatium vinosum, which grow optimally at 52, 49, and 25 ºC, respectively, have homologous cytochromes c' (PHCP, TTCP, and AVCP, respectively) exhibiting at least 50% amino acid sequence identity. Here, the thermal stability of the recombinant TTCP protein was first confirmed to be between those of PHCP and AVCP. Structure comparison of the three proteins and a mutagenesis study on TTCP revealed that hydrogen bonds and hydrophobic interactions between the heme and amino acid residues were responsible for their stability differences. In addition, PHCP, TTCP, and AVCP, and their variants with altered stability similarly bound nitric oxide and carbon oxide, but not oxygen. Therefore, the thermal stability of TTCP together with PHCP and AVCP can be tuned through specific interactions around the heme without affecting their gas-binding function. These cytochromes c' will be useful as specific gas sensor proteins exhibiting a wide thermal stability range.

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