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Title: Dependence of NO recombination dynamics in horse myoglobin on solution glycerol content

Abstract

The recombination dynamics of NO with horse heart myoglobin (Mb) following photolysis with a 570 nm excitation pulse were measured by time-resolved absorption with 250 fs temporal resolution. These measurements were carried out in room-temperature solutions in which the glycerol concentration was varied from 0 to 90% (w/v). The recombination of NO is nonsingle exponential in all cases,m but becomes faster as the glycerol concentration is increased. The interpretation of these results is aided by a maximum entropy analysis to determine a distribution of rate processes consistent with the data. This analysis suggests that in buffer there are two dominant rate processes for NO recombination on the subnanosecond time scale, one at {approx}10 ps and one at {approx}200 ps. The dominant effect of increasing glycerol content is to increase the amplitude of the fast process, with no corresponding significant change in rate, and to decrease the amplitude of the slow process, with no corresponding significant change in rate, and to decrease the amplitude of the slow process, but with a corresponding increase in rate. These results are consistent with a photodissociation process in which photolyzed NO partitions immediately between two distinct populations, one of which has a rapid and themore » other of which has a slower recombination. The rate of the rapid recombination is independent of glycerol concentration, and therefore decoupled from any protein relaxation process influenced by glycerol, while that of the slower recombination increases at higher glycerol concentration. Further, the partitioning between these two populations also depends on glycerol content, with the relative amplitude of the faster recombination process increasing as the glycerol content is increased. Interpretation of these observations in terms of ligand trajectories following photodissociation, and possible connections of these results with both infrared and crystallographic studies of photodissociated MbCO are discussed.« less

Authors:
; ; ;  [1]
  1. Los Alamos National Lab., NM (United States). Bioscience and Biotechnology Group
Publication Date:
Sponsoring Org.:
USDOE, Washington, DC (United States); National Insts. of Health, Bethesda, MD (United States)
OSTI Identifier:
696661
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical
Additional Journal Information:
Journal Volume: 103; Journal Issue: 37; Other Information: PBD: 16 Sep 1999
Country of Publication:
United States
Language:
English
Subject:
55 BIOLOGY AND MEDICINE, BASIC STUDIES; 40 CHEMISTRY; HORSES; MYOGLOBIN; NITRIC OXIDE; DYNAMICS; RECOMBINATION; PHOTOLYSIS; GLYCEROL; HEART

Citation Formats

Shreve, A.P., Franzen, S., Simpson, M.C., and Dyer, R.B. Dependence of NO recombination dynamics in horse myoglobin on solution glycerol content. United States: N. p., 1999. Web. doi:10.1021/jp991163g.
Shreve, A.P., Franzen, S., Simpson, M.C., & Dyer, R.B. Dependence of NO recombination dynamics in horse myoglobin on solution glycerol content. United States. doi:10.1021/jp991163g.
Shreve, A.P., Franzen, S., Simpson, M.C., and Dyer, R.B. Thu . "Dependence of NO recombination dynamics in horse myoglobin on solution glycerol content". United States. doi:10.1021/jp991163g.
@article{osti_696661,
title = {Dependence of NO recombination dynamics in horse myoglobin on solution glycerol content},
author = {Shreve, A.P. and Franzen, S. and Simpson, M.C. and Dyer, R.B.},
abstractNote = {The recombination dynamics of NO with horse heart myoglobin (Mb) following photolysis with a 570 nm excitation pulse were measured by time-resolved absorption with 250 fs temporal resolution. These measurements were carried out in room-temperature solutions in which the glycerol concentration was varied from 0 to 90% (w/v). The recombination of NO is nonsingle exponential in all cases,m but becomes faster as the glycerol concentration is increased. The interpretation of these results is aided by a maximum entropy analysis to determine a distribution of rate processes consistent with the data. This analysis suggests that in buffer there are two dominant rate processes for NO recombination on the subnanosecond time scale, one at {approx}10 ps and one at {approx}200 ps. The dominant effect of increasing glycerol content is to increase the amplitude of the fast process, with no corresponding significant change in rate, and to decrease the amplitude of the slow process, with no corresponding significant change in rate, and to decrease the amplitude of the slow process, but with a corresponding increase in rate. These results are consistent with a photodissociation process in which photolyzed NO partitions immediately between two distinct populations, one of which has a rapid and the other of which has a slower recombination. The rate of the rapid recombination is independent of glycerol concentration, and therefore decoupled from any protein relaxation process influenced by glycerol, while that of the slower recombination increases at higher glycerol concentration. Further, the partitioning between these two populations also depends on glycerol content, with the relative amplitude of the faster recombination process increasing as the glycerol content is increased. Interpretation of these observations in terms of ligand trajectories following photodissociation, and possible connections of these results with both infrared and crystallographic studies of photodissociated MbCO are discussed.},
doi = {10.1021/jp991163g},
journal = {Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical},
number = 37,
volume = 103,
place = {United States},
year = {1999},
month = {9}
}