scholarly journals Thermal denaturations of staphylococcal nuclease wild-type and mutants monitored by fluorescence and circular dichroism are similar: Lack of evidence for other than a two state thermal denaturation

2007 ◽  
Vol 125 (2-3) ◽  
pp. 490-496 ◽  
Author(s):  
Michael P. Byrne ◽  
Wesley E. Stites
Keyword(s):  
Circular Dichroism ◽  
Thermal Denaturation ◽  
Staphylococcal Nuclease ◽  
Wild Type ◽  
Circular Dichroïsm

Effect of Temperature and pH on the Secondary Structure and Denaturation Process of Jumbo Squid Hepatopancreas Cathepsin D.

2019 ◽  
Vol 26 (7) ◽  
pp. 532-541 ◽  
Author(s):  
Cadena-Cadena Francisco ◽  
Cárdenas-López José Luis ◽  
Ezquerra-Brauer Josafat Marina ◽  
Cinco-Moroyoqui Francisco Javier ◽  
López-Zavala Alonso Alexis ◽  
...  
Keyword(s):  
Circular Dichroism ◽  
Secondary Structure ◽  
Cathepsin D ◽  
Thermal Denaturation ◽  
Protein Denaturation ◽  
Marine Organisms ◽  
Effect Of Temperature ◽  
Jumbo Squid ◽  
Α Helix ◽  
Circular Dichroïsm

Background: Cathepsin D is a lysosomal enzyme that is found in all organisms acting in protein turnover, in humans it is present in some types of carcinomas, and it has a high activity in Parkinson's disease and a low activity in Alzheimer disease. In marine organisms, most of the research has been limited to corroborate the presence of this enzyme. It is known that cathepsin D of some marine organisms has a low thermostability and that it has the ability to have activity at very acidic pH. Cathepsin D of the Jumbo squid (Dosidicus gigas) hepatopancreas was purified and partially characterized. The secondary structure of these enzymes is highly conserved so the role of temperature and pH in the secondary structure and in protein denaturation is of great importance in the study of enzymes. The secondary structure of cathepsin D from jumbo squid hepatopancreas was determined by means of circular dichroism spectroscopy. Objective: In this article, our purpose was to determine the secondary structure of the enzyme and how it is affected by subjecting it to different temperature and pH conditions. Methods: Circular dichroism technique was used to measure the modifications of the secondary structure of cathepsin D when subjected to different treatments. The methodology consisted in dissecting the hepatopancreas of squid and freeze drying it. Then a crude extract was prepared by mixing 1: 1 hepatopancreas with assay buffer, the purification was in two steps; the first step consisted of using an ultrafiltration membrane with a molecular cut of 50 kDa, and the second step, a pepstatin agarose resin was used to purification the enzyme. Once the enzyme was purified, the purity was corroborated with SDS PAGE electrophoresis, isoelectric point and zymogram. Circular dichroism is carried out by placing the sample with a concentration of 0.125 mg / mL in a 3 mL quartz cell. The results were obtained in mdeg (millidegrees) and transformed to mean ellipticity per residue, using 111 g/mol molecular weight/residue as average. Secondary-structure estimation from the far-UV CD spectra was calculated using K2D Dichroweb software. Results: It was found that α helix decreases at temperatures above 50 °C and above pH 4. Heating the enzyme above 70°C maintains a low percentage of α helix and increases β sheet. Far-UV CD measurements of cathepsin D showed irreversible thermal denaturation. The process was strongly dependent on the heating rate, accompanied by a process of oligomerization of the protein that appears when the sample is heated, and maintained a certain time at this temperature. An amount typically between 3 and 4% α helix of their secondary structure remains unchanged. It is consistent with an unfolding process kinetically controlled due to the presence of an irreversible reaction. The secondary structure depends on pH, and a pH above 4 causes α helix structures to be modified. Conclusion: In conclusion, cathepsin D from jumbo squid hepatopancreas showed retaining up to 4% α helix at 80°C. The thermal denaturation of cathepsin D at pH 3.5 is under kinetic control and follows an irreversible model.

Circular dichroism and resonance Raman comparative studies of wild type cytochromec and F82H mutant

Biopolymers ◽  
2000 ◽  
Vol 57 (2) ◽  
pp. 77-84 ◽  
Author(s):  
Junwei Zheng ◽  
Shuyu Ye ◽  
Tianhong Lu ◽  
Therese M. Cotton ◽  
George Chumanov
Keyword(s):  
Circular Dichroism ◽  
Comparative Studies ◽  
Resonance Raman ◽  
Wild Type ◽  
Circular Dichroïsm

Structure of a Compact Peptide from Staphylococcal Nuclease Determined by Circular Dichroism and NMR Spectroscopy

Biochemistry ◽  
1995 ◽  
Vol 34 (17) ◽  
pp. 5795-5800 ◽  
Author(s):  
Mark W. Maciejewski ◽  
Micheal H. Zehfus
Keyword(s):  
Circular Dichroism ◽  
Nmr Spectroscopy ◽  
Staphylococcal Nuclease ◽  
Circular Dichroïsm

scholarly journals Thermal denaturation of sheared and unsheared chromatin by absorption and circular dichroism measurements

1976 ◽  
Vol 3 (8) ◽  
pp. 1875-1882 ◽  
Author(s):  
P. Miller ◽  
F. Kendall ◽  
C. Nicolini
Keyword(s):  
Circular Dichroism ◽  
Thermal Denaturation ◽  
Circular Dichroïsm

Tumor Suppressor p16INK4A:  Structural Characterization of Wild-Type and Mutant Proteins by NMR and Circular Dichroism†

Biochemistry ◽  
1996 ◽  
Vol 35 (29) ◽  
pp. 9475-9487 ◽  
Author(s):  
Anton Tevelev ◽  
In-Ja L. Byeon ◽  
Thomas Selby ◽  
Karen Ericson ◽  
Hee-Jung Kim ◽  
...  
Keyword(s):  
Circular Dichroism ◽  
Tumor Suppressor ◽  
Structural Characterization ◽  
Wild Type ◽  
Mutant Proteins ◽  
Circular Dichroïsm

Folding of staphylococcal nuclease A studied by equilibrium and kinetic circular dichroism spectra

Biochemistry ◽  
1991 ◽  
Vol 30 (10) ◽  
pp. 2698-2706 ◽  
Author(s):  
Tatsuro Sugawara ◽  
Kunihiro Kuwajima ◽  
Shintaro Sugai
Keyword(s):  
Circular Dichroism ◽  
Staphylococcal Nuclease ◽  
Circular Dichroism Spectra ◽  
Circular Dichroïsm

scholarly journals Interaction between Chromosomal Protein HMGB1 and DNA Studied by DNA-Melting Analysis

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Elena V. Chikhirzhina ◽  
Starkova J. Tatiana ◽  
Alexander M. Polyanichko
Keyword(s):  
Circular Dichroism ◽  
Thermal Denaturation ◽  
Circular Dichroism Spectroscopy ◽  
Dna Melting ◽  
Chromosomal Protein ◽  
Melting Temperatures ◽  
Melting Analysis ◽  
Circular Dichroïsm ◽  
Nonhistone Chromosomal Protein ◽  
Biphasic Process

Interaction of HMGB1 nonhistone chromosomal protein with DNA was studied using circular dichroism spectroscopy and thermal denaturation of DNA. Melting DNA in the complex was shown to be a biphasic process. The characteristic melting temperatures of unbound DNA and the DNA bound to HMGB1 in 0.25 mM EDTA solutions were found to beTmI=44.0±0.5°C andTmII=62.0±1°C, respectively. It was shown that the binding of the HMGB1 molecule affects the melting of the DNA region approximately 30 b.p. long.

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