Mossbauer studies of exchange-coupled two-iron centers in proteins
Sage, James Timothy
This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.
Permalink
https://hdl.handle.net/2142/25251
Description
Title
Mossbauer studies of exchange-coupled two-iron centers in proteins
Author(s)
Sage, James Timothy
Issue Date
1986
Doctoral Committee Chair(s)
Debrunner, Peter G.
Department of Study
Physics
Discipline
Physics
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Mossbauer
hemerythrin
uteroferrin
exchange coupling
Language
en
Abstract
This thesis reports Mossbauer measurements on three derivatives of
the oxygen-transport protein hemerythrin and on the oxidized and reduced
forms of uteroferrin, a purple acid phosphatase isolated from porcine
uterine fluid. Both proteins contain an exchange-coupled pair of iron
atoms coordinated directly to amino acid side chains.
A model that takes account of both the exchange coupling and the
zero-field splitting at each site is presented and used to describe the
magnetic properties of the ground spin multiplet of a pair of coupled
spins. One notable feature of the model is the fact that the g- and
A-tensors of the coupled system may be quite anisotropic even if the
corresponding single-site tensors are not.
The model is applied in several Kramers systems and explains some
unusual observations. In reduced uteroferrin, unexpectedly large
anisotropies in the hyperfine tensor at the ferric site are rationalized
naturally and in a way consistent with the. other magnetic properties.
Similar observations on a sulfide derivative of hemerythrin appear to be
susceptible to the same sort of explanation, although the Mossbauer
simulations are not as refined. An unusual EPR spectrum observed in a
nitric oxide derivative of deoxyhemerythrin is also explicable in the
spin-coupling model; the corresponding Mossbauer spectra are reported
but have not been analyzed in detail.
Preliminary studies of some non-Kramers systems are also presented.
The M~ssbauer spectrum of an azide derivative of deoxyhemerythrin
broadens in a small applied field, indicating the presence of a near
degeneracy. The spectrum of oxidized uteroferrin broadens as the
temperature is raised, even in the absence of an applied field. No
fully adequate explanation for the latter observation is apparent.
Use this login method if you
don't
have an
@illinois.edu
email address.
(Oops, I do have one)
IDEALS migrated to a new platform on June 23, 2022. If you created
your account prior to this date, you will have to reset your password
using the forgot-password link below.
