Probing the Acid-Induced Packing Structure Changes of the Molten Globule Domains of a Protein near Equilibrium Unfolding

2017 ◽  
Vol 8 (2) ◽  
pp. 470-477 ◽  
Author(s):  
Yi-Qi Yeh ◽  
Kuei-Fen Liao ◽  
Orion Shih ◽  
Ying-Jen Shiu ◽  
Wei-Ru Wu ◽  
...  
Keyword(s):  
Molten Globule ◽  
Packing Structure ◽  
Structure Changes ◽  
Equilibrium Unfolding

Denaturant Induced Equilibrium Unfolding and Conformational Transitional Studies of Germinated Fenugreek β-Amylase Revealed Molten Globule like State at Low pH

2020 ◽  
Vol 27 (10) ◽  
pp. 1046-1057
Author(s):  
Dinesh Chand Agrawal ◽  
Anjali Yadav ◽  
Mohd. Asim Khan ◽  
Suman Kundu ◽  
Arvind M. Kayastha
Keyword(s):  
Circular Dichroism ◽  
Catalytic Domain ◽  
Molten Globule ◽  
Intrinsic Fluorescence ◽  
Tertiary Structures ◽  
Near Ultraviolet ◽  
Equilibrium Unfolding ◽  
Α Helix ◽  
Far Ultraviolet ◽  
Circular Dichroïsm

Background: β-Amylase (EC 3.2.1.2) is a maltogenic enzyme, which releases β-maltose from the non-reducing end of the substrates. The enzyme plays important roles for the production of vaccine, maltiol and maltose rich syrups. Apart from these applications the enzyme protects cells from abiotic as well as oxidative damage. The enzyme is βwell characterized in βplants and microbes and crystal structures of β-amylases βhave been βobtained from sweet potato, soybean and Bacillus cereus. Objective: Find out correlation between structural and functional stability induced by change in pH, temperature and chaotropes. Methods: Activity, intrinsic fluorescence, extrinsic fluorescence, near- and far- ultraviolet circular dichroism spectroscopic measurements were performed. Results: Peaks about 208 nm and 222 nm obtained by near-ultraviolet circular dichroism correspond to α-helix whereas peak at 215 nm shows presence of β-sheet. At pH 2.0, absence of tertiary structures, exposed of hydrophobic regions and presence of substantial secondary structures, revealed the existence of molten globule like state. Temperature induced denaturation studies showed that the enzyme was stable up to 75 ºC and the process was found to be irreversible in nature. Chaotropes dependent equilibrium unfolding studies revealed that at low concentration of chaotropes, ellipticity and intrinsic fluorescence βintensity were βdecreased βwhereas βenzymatic activity remained unchanged, which revealed fenugreek β-amylase is multi-domains enzyme and catalytic βdomain βis more βstable compare to non-catalytic domain. Moreover, the transition was sigmoidal and non-coincidental. Conclusion: Results indicate the probable existence of intermediate states that might perform significant role in physiological process and biotechnological applications.

scholarly journals Folding mechanism of canine milk lysozyme studied by circular dichroism and fluorescence spectroscopy

2003 ◽  
Vol 17 (2-3) ◽  
pp. 183-193 ◽  
Author(s):  
Masaharu Nakao ◽  
Munehito Arai ◽  
Takumi Koshiba ◽  
Katsutoshi Nitta ◽  
Kunihiro Kuwajima
Keyword(s):  
Circular Dichroism ◽  
Fluorescence Spectroscopy ◽  
Molten Globule ◽  
Guanidine Hydrochloride ◽  
Folding Intermediates ◽  
Equilibrium Unfolding ◽  
Burst Phase ◽  
The Relationship ◽  
Kinetics Of ◽  
Circular Dichroïsm

We have studied the guanidine hydrochloride‒induced equilibrium unfolding and the kinetics of refolding of canine milk lysozyme by circular dichroism and fluorescence spectroscopy. The thermodynamic analysis of the equilibrium unfolding measured by circular dichroism and fluorescence has shown that unfolding is represented by a three‒state mechanism and that the intermediate state of canine milk lysozyme is remarkably more stable than the intermediates observed in other lysozyme and α-lactalbumin. In the kinetic refolding of this protein, there are at least two kinetic intermediates; a burst=phase intermediate accumulated within the dead time (4 ms) of the measurement and an intermediate that has been observed during the kinetics with a rate constant of 10–20 s–1after the burst phase. This result is apparently in contrast with those previously observed in the kinetic refolding of α‒lactalbumin and equine lysozyme that show only the burst‒phase intermediate. The relationship between the extraordinarily stable equilibrium molten globule and the kinetic folding intermediates will be discussed.

scholarly journals Predissociated Dimers and Molten Globule Monomers in the Equilibrium Unfolding of Yeast Glutathione Reductase

2003 ◽  
Vol 85 (5) ◽  
pp. 3255-3261 ◽  
Author(s):  
Paulo Roberto Louzada ◽  
Adriano Sebollela ◽  
Marcelo E. Scaramello ◽  
Sérgio T. Ferreira
Keyword(s):  
Glutathione Reductase ◽  
Molten Globule ◽  
Equilibrium Unfolding

Determination of interface width using EELS fine structure changes

1991 ◽  
Vol 49 ◽  
pp. 730-731
Author(s):  
Vinayak P. Dravid ◽  
M.R. Notis ◽  
C.E. Lyman
Keyword(s):  
Fine Structure ◽  
Materials Science ◽  
Input Parameter ◽  
Core Loss ◽  
Directionally Solidified ◽  
Interface Width ◽  
Structure Changes ◽  
Important Input ◽  
Directionally Solidified Eutectics

The concept of interfacial width is often invoked in many materials science phenomena which relate to the structure and properties of internal interfaces. The numerical value of interface width is an important input parameter in diffusion equations, sintering theories as well as in many electronic devices/processes. Most often, however, this value is guessed rather than determined or even estimated. In this paper we present a method of determining the effective structural and electronic- structural width of interphase interfaces using low- and core loss fine structure effects in EELS spectra.The specimens used in the study were directionally solidified eutectics (DSEs) in the system; NiO-ZrO2(CaO), NiO-Y2O3 and MnO-ZrO2(ss). EELS experiments were carried out using a VG HB-501 FE STEM and a Hitachi HF-2000 FE TEM.

In-Situ Observation of Clay Minerals Hydrated and Intercalated With Liquid Chemicals Using Film-Sealed Environmental Cell

1980 ◽  
Vol 38 ◽  
pp. 208-209 ◽  
Author(s):  
K. Fukushima ◽  
N. Kohyama ◽  
A. Fukami
Keyword(s):  
Carbon Film ◽  
Resolving Power ◽  
In Situ Observation ◽  
Interlayer Water ◽  
Saturated Water ◽  
Structure Changes ◽  
Environmental Cell ◽  
Gas Layer ◽  
20 Nm

A film-sealed high resolution environmental cell(E.C) for observing hydrated materials had been developed by us(l). Main specification of the E.C. is as follows: 1) Accelerated voltage; 100 kV. 2) Gas in the E.C.; saturated water vapour with carrier gas of 50 Torr. 3) Thickness of gas layer; 50 μm. 4) Sealing film; evaporated carbon film(20 nm thick) with plastic microgrid. 5) Resolving power; 1 nm. 6) Transmittance of electron beam; 60% at 100 kV. The E.C. had been successfully applied to the study of hydrated halloysite(2) (3). Kaolin minerals have no interlayer water and are basically non-expandable but form intercalation compounds with some specific chemicals such as hydrazine, formamide and etc. Because of these compounds being mostly changed in vacuum, we tried to reveal the structure changes between in wet air and in vacuum of kaolin minerals intercalated with hydrazine and of hydrated state of montmori1lonite using the E.C. developed by us.

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