NDLI: A pH dependence study on the unfolding and refolding of apoazurin : Comparison with Zn(II) auzurin

Content Provider	Springer Nature Link
Author	Hansen, John E. McBrayer, Mary Kate Robbins, Michael Suh, Yong
Copyright Year	2002
Abstract	Azurin, a small blue copper protein from the bacterial species Pseudomonas aeruginosa, is mostly a β-sheet protein arranged into a single domain. Previous folding studies have shown that the equilibrium denaturation of the holoprotein follows a two-state process; however, upon removal of the copper, the denaturation had been reported to follow a three-state process. The two unfolding transitions measured for apoazurin had been thought to arise from two different folding domains. However, in the present work, we found that the denaturation of apoazurin occurs over a single transition and we determined the folding free energy to be −27.8±2.4 kJ mol$^{−1}$. From this measurement along with measurements previously reported for the unfolding of the holoazurin, we were able to determine that Cu(II) and Cu(I) stabilize the native structure by 25.1±6.9 kJ/mol and 12.9±8.1 kJ/mol, respectively. It is our contention that the second transition displayed in the denaturation curves previously reported for apoazurin arise from protein heterogeneity—in particular, from the presence of Zn(II) azurin. We extended our investigation into the denaturation of Zn(II) azurin at pH 6.0 and 7.5. The equilibrium denaturation studies show that the zinc ion significantly stabilizes the native-state structure at pH 7.5 and very little at the lower pH. We attribute the decrease in the stabilizing effect of the zinc ion with decreasing pH to the protonation of two histidinyl side chains. When protonated the ligands, His 46 and His 117, are incapable of binding a metal ion. Further, comparing the denaturation curves of Zn(II) azurin measured by circular dichroism with those measured by fluorescence indicates that the denaturation of Zn(II) azurin is far less simple than the denaturation of apoazurin.
Starting Page	19
Ending Page	40
Page Count	22
File Format	PDF
ISSN	10859195
Journal	Cell Biochemistry and Biophysics
Volume Number	36
Issue Number	1
e-ISSN	15590283
Language	English
Publisher	Humana Press
Publisher Date	2002-01-01
Publisher Place	Totowa
Access Restriction	One Nation One Subscription (ONOS)
Subject Keyword	Biochemistry Pharmacology/Toxicology Biotechnology Cell Biology
Content Type	Text
Resource Type	Article
Subject	Cell Biology Medicine Biochemistry Biophysics

Sl.	Authority	Responsibilities	Communication Details
1	Ministry of Education (GoI), Department of Higher Education	Sanctioning Authority	https://www.education.gov.in/ict-initiatives
2	Indian Institute of Technology Kharagpur	Host Institute of the Project: The host institute of the project is responsible for providing infrastructure support and hosting the project	https://www.iitkgp.ac.in
3	National Digital Library of India Office, Indian Institute of Technology Kharagpur	The administrative and infrastructural headquarters of the project	Dr. B. Sutradhar bsutra@ndl.gov.in
4	Project PI / Joint PI	Principal Investigator and Joint Principal Investigators of the project	Dr. B. Sutradhar bsutra@ndl.gov.in Prof. Saswat Chakrabarti will be added soon
5	Website/Portal (Helpdesk)	Queries regarding NDLI and its services	support@ndl.gov.in
6	Contents and Copyright Issues	Queries related to content curation and copyright issues	content@ndl.gov.in
7	National Digital Library of India Club (NDLI Club)	Queries related to NDLI Club formation, support, user awareness program, seminar/symposium, collaboration, social media, promotion, and outreach	clubsupport@ndl.gov.in
8	Digital Preservation Centre (DPC)	Assistance with digitizing and archiving copyright-free printed books	dpc@ndl.gov.in
9	IDR Setup or Support	Queries related to establishment and support of Institutional Digital Repository (IDR) and IDR workshops	idr@ndl.gov.in

A Partially Folded State of Ovalbumin at Low pH Tends to Aggregate

Aspirin interaction with ribonuclease a

Effects of tumors on inhaled pharmacologic drugs : II. Particle motion

The effects of drug complexation on the stability and conformation of human serum albumin : Protein unfolding

A computational comparison of the atomic models of the actomyosin interface

Poster abstracts

Lecture abstracts

Redox status of the eye lens : A regional study

Arrestin interaction with rhodopsin : Conceptual models

A pH dependence study on the unfolding and refolding of apoazurin : Comparison with Zn(II) auzurin

Similar Documents

A Partially Folded State of Ovalbumin at Low pH Tends to Aggregate

Aspirin interaction with ribonuclease a

Effects of tumors on inhaled pharmacologic drugs : II. Particle motion

The effects of drug complexation on the stability and conformation of human serum albumin : Protein unfolding

A computational comparison of the atomic models of the actomyosin interface

Poster abstracts

Lecture abstracts

Redox status of the eye lens : A regional study

Arrestin interaction with rhodopsin : Conceptual models

A pH dependence study on the unfolding and refolding of apoazurin : Comparison with Zn(II) auzurin