Effects of temperature and concentration on bovine lens α-crystallin secondary structure: a circular dichroism spectroscopic study

Farnsworth, Patricia N.; Groth-Vasselli, Barbara; Greenfield, Norma J.; Singh, Kamalendra

doi:10.1016/s0141-8130(97)00028-7

Cited by 30 publications

(22 citation statements)

References 31 publications

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“…In this present study, MIP_05962 protein behaves like a typical sHSP in terms of its secondary structure, oligomeric size and chaperone functions. The secondary structural composition of MIP_05962 protein is quite similar with that secondary structure of well known characterized HSP20 family proteins such as α‐crystallin protein , HSP16.3 of M.tb , HSP18 of M. leprae HSP16.5 of M. jannaschii and IbpB of E. coli reported as in literature. MIP_05962 is slightly more thermal stable protein than HSP18 of M. leprae HSP16.3 of M.tb and IbpB of E. coli but less stable than HSP16.5 of M. Jannaschii .…”

Section: Discussionsupporting

confidence: 77%

“…Methanococcus jannaschii HSP16.5 crystal structure also revealed that it contains more of β sheets . Yang analysis for secondary structure composition of native MIP_05962 is similar to the secondary structure of α‐crystallin protein and with other sHSPs. Apparently, MIP_05962 was found to be resistant to higher temperatures and no alteration in secondary structure composition and shift of λ max was observed up to 60 °C.…”

Section: Discussionmentioning

confidence: 81%

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Immunodominant protein MIP_05962 from Mycobacterium indicus pranii displays chaperone activity

et al. 2017

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Tuberculosis, a contagious disease of infectious origin is currently a major cause of deaths worldwide. Mycobacterium indicus pranii (MIP), a saprophytic nonpathogen and a potent immunomodulator is currently being investigated as an intervention against tuberculosis along with many other diseases with positive outcome. The apparent paradox of multiple chaperones in mycobacterial species and enigma about the cellular functions of the client proteins of these chaperones need to be explored. Chaperones are the known immunomodulators; thus, there is need to exploit the proteome of MIP for identification and characterization of putative chaperones. One of the immunogenic proteins, MIP_05962 is a member of heat shock protein (HSP) 20 family due to the presence of α-crystallin domain, and has amino acid similarity with Mycobacterium lepraeHSP18 protein. The diverse functions of M. lepraeHSP18 in stress conditions implicate MIP_05962 as an important protein that needs to be explored. Biophysical and biochemical characterization of the said protein proved it to be a chaperone. The observations of aggregation prevention and refolding of substrate proteins in the presence of MIP_05962 along with interaction with non-native proteins, surface hydrophobicity, formation of large oligomers, in-vivo thermal rescue of Escherichia coli expressing MIP_05962, enhancing solubility of insoluble protein maltodextrin glucosidase (MalZ) under in-vivo conditions, and thermal stability and reversibility confirmed MIP_05962 as a molecular chaperone.

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Section: Discussionsupporting

confidence: 77%

Section: Discussionmentioning

confidence: 81%

Immunodominant protein MIP_05962 from Mycobacterium indicus pranii displays chaperone activity

et al. 2017

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“…As this calculation is based on a dataset of monomeric proteins, the theoretical value for the complete denaturation of an oligomeric α‐crystallin is expected to be even higher,19 particularly due to the hydrophobic nature of interaction between the subunits 20–22. Similarly, the theoretical heat capacity change on denaturation (Δ C P ), calculated by two different approaches,18, 23, 24 is almost twice the experimentally determined value9 (see Table I).…”

Section: Introductionmentioning

confidence: 84%

“…However, the chaperone‐like activity of the protein is retained within and above its thermal transition 2, 16, 17. The reported values of the calorimetric enthalpy of denaturation (Δ H cal ) range widely from 63 to 336 kJ mol −1 per α‐crystallin subunit,9, 11 but even the highest reported value of 336 kJ mol −1 is well below the expected denaturation enthalpy of ∼510 kJ mol −1 calculated on the basis of protein size using the method of Robertson and Murphy 18. As this calculation is based on a dataset of monomeric proteins, the theoretical value for the complete denaturation of an oligomeric α‐crystallin is expected to be even higher,19 particularly due to the hydrophobic nature of interaction between the subunits 20–22.…”

Section: Introductionmentioning

confidence: 99%

Thermal and acid denaturation of bovine lens α‐crystallin

et al. 2011

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The chaperone-like protein α-crystallin is a ∼35 subunit hetero-oligomer consisting of αA and αB subunits in a 3:1 molar ratio and has the function of maintaining eye lens transparency. We studied the thermal denaturation of α-crystallin by differential scanning calorimetry (DSC), circular dichroism (CD), and dynamic light scattering (DLS) as a function of pH. Our results show that between pH 7 and 10 the protein undergoes a reversible thermal transition. However, the thermodynamic parameters obtained by DSC are inconsistent with the complete denaturation of an oligomeric protein of the size of α-crystallin. Accordingly, the CD data suggest the presence of extensive residual secondary structure above the transition temperature. Within the pH range from 4 to 7 the increased aggregation propensity around the isoelectric point (pI ∼ 6) precludes observation of a thermal transition. As pH decreases below 4 the protein undergoes a substantial unfolding. The secondary structure content of the acid-denatured state shows little sensitivity to heating. We propose that the thermal transition above pH 7 and the acid-induced transition at ambient temperature result in predominant denaturation of the αB subunit. Although the extent of denaturation of the αA subunit cannot be estimated from the current data, the existence of a native-like conformation is suggested by the preserved association of the subunits and the chaperone-like activity. A key difference between the thermal and the acid denaturation is that the latter is accompanied by dissociation of αB subunits from the remaining αA-oligomer, as supported by DLS studies.

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“…Hitherto, almost all investigated sHSPs can form into large oligomers [13]. The numbers of subunits in these oligomers are extremely variable among species, and the status of complexes, which are poly-disperse in size and shape [14,15], are temperature-and concentration-dependent [16,17]. The -crystallin domain was confirmed to be vital in both oligomerization and chaperone function [18].…”

Section: Introductionmentioning

confidence: 99%

Importance of a Potential Salt Bridge and Hydrophobic Core in the Function and Oligomerization of a Small Heat Shock Protein

Wen

Wang²,

Xu³

et al. 2010

PPL

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Effects of temperature and concentration on bovine lens α-crystallin secondary structure: a circular dichroism spectroscopic study

Cited by 30 publications

References 31 publications

Immunodominant protein MIP_05962 from Mycobacterium indicus pranii displays chaperone activity

Immunodominant protein MIP_05962 from Mycobacterium indicus pranii displays chaperone activity

Thermal and acid denaturation of bovine lens α‐crystallin

Importance of a Potential Salt Bridge and Hydrophobic Core in the Function and Oligomerization of a Small Heat Shock Protein

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