Kinetics of the alkaline tetramer → dimer dissociation in liganded human hemoglobin

A laser light-scattering stopped-flow study

D. P. Flamig, Lawrence J Parkhurst

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

The first-order dissociation of tetrameric HbCO to the dimer has been studied over the pH range 10.30-11.57 in a light-scattering stopped-flow apparatus using argon-ion laser excitation. The first-order dissociation rate constant varies from 0.25 sec-1 to 24.0 sec-1 over this pH interval. A semilogarithmic plot of k versus pH has a slope of 2.56 at pH 11.07, the midpoint. The pH dependence of the dissociation of the tetramer is consistent with progressive titration of α12 and β12 salt bridges. At pH 10.66 the dissociation rates of HbO2, HbCO, methemoglobin, and HbCN vary less than 20% from their mean value. A study of the dissociation kinetics as a function of protein concentration allows one to obtain both association and dissociation rate constants, and hence equilibrium constants, for the tetramer ⇆ dimer reaction. In this manner, equilibrium constants were obtained on protein solutions with less than 15 sec of exposure to dissociating conditions.

Original languageEnglish (US)
Pages (from-to)3814-3816
Number of pages3
JournalProceedings of the National Academy of Sciences of the United States of America
Volume74
Issue number9
DOIs
StatePublished - Jan 1 1977

Fingerprint

Hemoglobins
Lasers
Light
Methemoglobin
Gas Lasers
Proteins
Salts

ASJC Scopus subject areas

  • General

Cite this

@article{5e5038798b234fa7972e7401d78764f0,
title = "Kinetics of the alkaline tetramer → dimer dissociation in liganded human hemoglobin: A laser light-scattering stopped-flow study",
abstract = "The first-order dissociation of tetrameric HbCO to the dimer has been studied over the pH range 10.30-11.57 in a light-scattering stopped-flow apparatus using argon-ion laser excitation. The first-order dissociation rate constant varies from 0.25 sec-1 to 24.0 sec-1 over this pH interval. A semilogarithmic plot of k versus pH has a slope of 2.56 at pH 11.07, the midpoint. The pH dependence of the dissociation of the tetramer is consistent with progressive titration of α1-α2 and β1-β2 salt bridges. At pH 10.66 the dissociation rates of HbO2, HbCO, methemoglobin, and HbCN vary less than 20{\%} from their mean value. A study of the dissociation kinetics as a function of protein concentration allows one to obtain both association and dissociation rate constants, and hence equilibrium constants, for the tetramer ⇆ dimer reaction. In this manner, equilibrium constants were obtained on protein solutions with less than 15 sec of exposure to dissociating conditions.",
author = "Flamig, {D. P.} and Parkhurst, {Lawrence J}",
year = "1977",
month = "1",
day = "1",
doi = "10.1073/pnas.74.9.3814",
language = "English (US)",
volume = "74",
pages = "3814--3816",
journal = "Proceedings of the National Academy of Sciences of the United States of America",
issn = "0027-8424",
number = "9",

}

TY - JOUR

T1 - Kinetics of the alkaline tetramer → dimer dissociation in liganded human hemoglobin

T2 - A laser light-scattering stopped-flow study

AU - Flamig, D. P.

AU - Parkhurst, Lawrence J

PY - 1977/1/1

Y1 - 1977/1/1

N2 - The first-order dissociation of tetrameric HbCO to the dimer has been studied over the pH range 10.30-11.57 in a light-scattering stopped-flow apparatus using argon-ion laser excitation. The first-order dissociation rate constant varies from 0.25 sec-1 to 24.0 sec-1 over this pH interval. A semilogarithmic plot of k versus pH has a slope of 2.56 at pH 11.07, the midpoint. The pH dependence of the dissociation of the tetramer is consistent with progressive titration of α1-α2 and β1-β2 salt bridges. At pH 10.66 the dissociation rates of HbO2, HbCO, methemoglobin, and HbCN vary less than 20% from their mean value. A study of the dissociation kinetics as a function of protein concentration allows one to obtain both association and dissociation rate constants, and hence equilibrium constants, for the tetramer ⇆ dimer reaction. In this manner, equilibrium constants were obtained on protein solutions with less than 15 sec of exposure to dissociating conditions.

AB - The first-order dissociation of tetrameric HbCO to the dimer has been studied over the pH range 10.30-11.57 in a light-scattering stopped-flow apparatus using argon-ion laser excitation. The first-order dissociation rate constant varies from 0.25 sec-1 to 24.0 sec-1 over this pH interval. A semilogarithmic plot of k versus pH has a slope of 2.56 at pH 11.07, the midpoint. The pH dependence of the dissociation of the tetramer is consistent with progressive titration of α1-α2 and β1-β2 salt bridges. At pH 10.66 the dissociation rates of HbO2, HbCO, methemoglobin, and HbCN vary less than 20% from their mean value. A study of the dissociation kinetics as a function of protein concentration allows one to obtain both association and dissociation rate constants, and hence equilibrium constants, for the tetramer ⇆ dimer reaction. In this manner, equilibrium constants were obtained on protein solutions with less than 15 sec of exposure to dissociating conditions.

UR - http://www.scopus.com/inward/record.url?scp=0017716891&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0017716891&partnerID=8YFLogxK

U2 - 10.1073/pnas.74.9.3814

DO - 10.1073/pnas.74.9.3814

M3 - Article

VL - 74

SP - 3814

EP - 3816

JO - Proceedings of the National Academy of Sciences of the United States of America

JF - Proceedings of the National Academy of Sciences of the United States of America

SN - 0027-8424

IS - 9

ER -