Thermal stability of collagen in naturally ageing and in vitro glycated rabbit tissues

Urea in renal medullas is sufficiently high to perturb macromolecules, yet the cells survive and function. The counteracting osmolytes hypothesis holds that methylamines, such as glycine betaine (betaine) and glycerophosphocholine (GPC) in renal medullas, stabilize macromolecules and oppose the effects of urea. Although betaine counteracts effects of urea on macromolecules in vitro and protects renal cells from urea in tissue culture, renal cells accumulate GPC rather than betaine in response to high urea both in vivo and in tissue culture. A proposed explanation is that GPC counteracts urea more effectively than betaine. However, we previously found GPC slightly less effective than betaine in counteracting inhibition of pyruvate kinase activity by urea. To test another macromolecule, we now compare GPC and betaine in counteracting reduction of the thermal stability of RNase A by urea. We find that urea decreases the thermal transition temperature and that betaine and GPC increase it, counteracting urea approximately equally. Therefore, the preference for GPC in response to high urea presumably has some other basis, such as a lower metabolic cost of GPC accumulation.

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Synthesis and investigation of in vitro cytotoxic activities and thermal stability of novel pyridine derivative platinum (II) complexes vis a vis DFT studies

Polyhedron ◽

10.1016/j.poly.2021.115492 ◽

2021 ◽

pp. 115492

Author(s):

Emine Kutlu ◽

Fatih Mehmet Emen ◽

Görkem Kismali ◽

Neslihan Kaya Kınaytürk ◽

Ali Ihsan Karacolak ◽

...

Keyword(s):

Thermal Stability ◽

Pyridine Derivative ◽

Cytotoxic Activities ◽

Dft Studies ◽

Thermal Stability Of

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The formation and thermal stability of in vitro assembled fibrils from acid-soluble and pepsin-treated collagens

Biochimica et Biophysica Acta (BBA) - Protein Structure ◽

10.1016/0005-2795(79)90149-1 ◽

1979 ◽

Vol 580 (2) ◽

pp. 372-381 ◽

Cited By ~ 20

Author(s):

John McK. Snowden ◽

David A. Swann

Keyword(s):

Thermal Stability ◽

Thermal Stability Of

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Thermal stability of collagen in relation to non-enzymatic glycosylation and browning in vitro

Diabetologia ◽

10.1007/bf00291977 ◽

1985 ◽

Vol 28 (9) ◽

pp. 687-691 ◽

Cited By ~ 24

Author(s):

T. T. Andreassen ◽

H. Oxlund

Keyword(s):

Thermal Stability ◽

Thermal Stability Of ◽

Enzymatic Glycosylation

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THE THERMAL STABILITY OF RHODOPSIN AND OPSIN

The Journal of General Physiology ◽

10.1085/jgp.42.2.259 ◽

1958 ◽

Vol 42 (2) ◽

pp. 259-280 ◽

Cited By ~ 113

Author(s):

Ruth Hubbard

Keyword(s):

Thermal Stability ◽

Thermal Denaturation ◽

Species Differences ◽

Activation Energies ◽

Specific Relationship ◽

Thermal Bleaching ◽

Thermal Stability Of ◽

Cis Isomer

Rhodopsin, the red photosensitive pigment of rod vision, is composed of a specific cis isomer of retinene, neo-b (11-cis), joined as chromophore to a colorless protein, opsin. We have investigated the thermal denaturation of cattle rhodopsin and opsin in aqueous digitonin solution, and in isolated rod outer limbs. Both rhodopsin and opsin are more stable in rods than in solution. In solution as well as in rods, moreover, rhodopsin is considerably more stable than opsin. The chromophore therefore protects opsin against denaturation. This is true whether rhodopsin is extracted from dark-adapted retinas, or synthesized in vitro from neo-b retinene and opsin. Excess neo-b retinene does not protect rhodopsin against denaturation. The protection involves the specific relationship between the chromophore and opsin. Similar, though somewhat less, protection is afforded opsin by the stereoisomeric iso-a (9-cis) chromophore in isorhodopsin. The Arrhenius activation energies (Ea) and entropies of activation (ΔS‡) are much greater for thermal denaturation of rhodopsin and isorhodopsin than of opsin. Furthermore, these values differ considerably for rhodopsins from different species —frog, squid, cattle—presumably due to species differences in the opsins. Heat or light bleaches rhodopsin by different mechanisms, yielding different products. Light stereoisomerizes the retinene chromophore; heat denatures the opsin. Photochemical bleaching therefore yields all-trans retinene and native opsin; thermal bleaching, neo-b retinene and denatured opsin.

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Bipartite Signal for Genomic RNA Dimerization in Moloney Murine Leukemia Virus

Journal of Virology ◽

10.1128/jvi.76.7.3135-3144.2002 ◽

2002 ◽

Vol 76 (7) ◽

pp. 3135-3144 ◽

Cited By ~ 33

Author(s):

Hinh Ly ◽

Tristram G. Parslow

Keyword(s):

Thermal Stability ◽

Murine Leukemia Virus ◽

Leukemia Virus ◽

Point Mutations ◽

Moloney Murine Leukemia Virus ◽

Genomic Rna ◽

Rna Dimerization ◽

Thermal Stability Of ◽

Murine Leukemia

ABSTRACT Retroviral virions each contain two identical genomic RNA strands that are stably but noncovalently joined in parallel near their 5′ ends. For certain viruses, this dimerization has been shown to depend on a unique RNA stem-loop locus, called the dimer initiation site (DIS), that efficiently homodimerizes through a palindromic base sequence in its loop. Previous studies with Moloney murine leukemia virus (Mo-MuLV) identified two alternative DIS loci that can each independently support RNA dimerization in vitro but whose relative contributions are unknown. We now report that both of these loci contribute to the assembly of the Mo-MuLV dimer. Using targeted deletions, point mutagenesis, and antisense oligonucleotides, we found that each of the two stem-loops forms as predicted and contributes independently to dimerization in vitro through a mechanism involving autocomplementary interactions of its loop. Disruption of either DIS locus individually reduced both the yield and the thermal stability of the in vitro dimers, whereas disruption of both eliminated dimerization altogether. Similarly, the thermal stability of virion-derived dimers was impaired by deletion of both DIS elements, and point mutations in either element produced defects in viral replication that correlated with their effects on in vitro RNA dimerization. These findings support the view that in some retroviruses, dimer initiation and stability involve two or more closely linked DIS loci which together align the nascent dimer strands in parallel and in register.

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Impact of A134 and E218 Amino Acid Residues of Tropomyosin on Its Flexibility and Function

International Journal of Molecular Sciences ◽

10.3390/ijms21228720 ◽

2020 ◽

Vol 21 (22) ◽

pp. 8720

Author(s):

Marina A. Marchenko ◽

Victoria V. Nefedova ◽

Daria S. Yampolskaya ◽

Galina V. Kopylova ◽

Daniil V. Shchepkin ◽

...

Keyword(s):

Thermal Stability ◽

Fine Tuning ◽

Actin Binding ◽

Sliding Velocity ◽

Scanning Calorimetry ◽

In Vitro Motility Assay ◽

In Vitro Motility ◽

High Flexibility ◽

Thermal Stability Of

Tropomyosin (Tpm) is one of the major actin-binding proteins that play a crucial role in the regulation of muscle contraction. The flexibility of the Tpm molecule is believed to be vital for its functioning, although its role and significance are under discussion. We choose two sites of the Tpm molecule that presumably have high flexibility and stabilized them with the A134L or E218L substitutions. Applying differential scanning calorimetry (DSC), molecular dynamics (MD), co-sedimentation, trypsin digestion, and in vitro motility assay, we characterized the properties of Tpm molecules with these substitutions. The A134L mutation prevented proteolysis of Tpm molecule by trypsin, and both substitutions increased the thermal stability of Tpm and its bending stiffness estimated from MD simulation. None of these mutations affected the primary binding of Tpm to F-actin; still, both of them increased the thermal stability of the actin-Tpm complex and maximal sliding velocity of regulated thin filaments in vitro at a saturating Ca2+ concentration. However, the mutations differently affected the Ca2+ sensitivity of the sliding velocity and pulling force produced by myosin heads. The data suggest that both regions of instability are essential for correct regulation and fine-tuning of Ca2+-dependent interaction of myosin heads with F-actin.

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