Binding and Electrostatic Attraction of Lanthanum (La3+) and Aluminum (Al3+) to Wheat Root Plasma Membranes

Binding and Electrostatic Attraction of Lanthanum (La3+) and Aluminum (Al3+) to Wheat Root Plasma... A general model for the sorption of trivalent cations to wheat-root (Triticum aestivum L cv. Scout 66) plasma membranes (PM) has been developed and includes the first published coefficients for La3+ and Al3+ binding to a biological membrane. Both ions are rhizotoxic, and the latter ion is the principal contributor to the toxicity of acidic soils around the world. The model takes into account both the electrostatic attraction and the binding of cations to the negatively charged PM surface. Ion binding is modeled as the reaction P −+I Z⇌PI Z −1 in which P − represents a negatively charged PM ligand, located in an estimated area of 540 Å2, and I Z represents an ion of charge Z. Binding constants for the reaction were assigned for K+ (1 m −1) and Ca2+ (30 m −1) and evaluated experimentally for La3+ (2200 m −1) and H+ (21,500 m −1). Al sorption is complicated by Al3+ hydrolysis that yields hydroxoaluminum species that are also sorbed. Binding constants of 30 and 1 m −1 were assigned for AlOH2+ and Al(OH)+ 2, respectively, then a constant for Al3+ (20,000 m −1) was evaluated experimentally using the previously obtained values for K+, Ca2+ and H+ binding. Electrostatic attraction was modeled according to Gouy-Chapman theory. Evaluation of parameters was based upon the sorption of ions to PM vesicles suspended in solutions containing variable concentrations of H+, Ca2+ and La3+ or Al3+. Use of small volumes, and improved assay techniques, allowed the measurement of concentration depletions caused by sorption to vesicles. Some independent confirmation of our model is provided by substantial agreement between our computations and two published reports of La3+ effects upon zeta potentials of plant protoplasts. The single published report concerning the electrostatic effects of Al on cell membranes is in essential agreement with the model. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Binding and Electrostatic Attraction of Lanthanum (La3+) and Aluminum (Al3+) to Wheat Root Plasma Membranes

Loading next page...
 
/lp/springer_journal/binding-and-electrostatic-attraction-of-lanthanum-la3-and-aluminum-al3-Pl1TnfhUwr
Publisher
Springer-Verlag
Copyright
Copyright © Inc. by 1997 Springer-Verlag New York
Subject
Life Sciences; Biochemistry, general; Human Physiology
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s002329900287
Publisher site
See Article on Publisher Site

Abstract

A general model for the sorption of trivalent cations to wheat-root (Triticum aestivum L cv. Scout 66) plasma membranes (PM) has been developed and includes the first published coefficients for La3+ and Al3+ binding to a biological membrane. Both ions are rhizotoxic, and the latter ion is the principal contributor to the toxicity of acidic soils around the world. The model takes into account both the electrostatic attraction and the binding of cations to the negatively charged PM surface. Ion binding is modeled as the reaction P −+I Z⇌PI Z −1 in which P − represents a negatively charged PM ligand, located in an estimated area of 540 Å2, and I Z represents an ion of charge Z. Binding constants for the reaction were assigned for K+ (1 m −1) and Ca2+ (30 m −1) and evaluated experimentally for La3+ (2200 m −1) and H+ (21,500 m −1). Al sorption is complicated by Al3+ hydrolysis that yields hydroxoaluminum species that are also sorbed. Binding constants of 30 and 1 m −1 were assigned for AlOH2+ and Al(OH)+ 2, respectively, then a constant for Al3+ (20,000 m −1) was evaluated experimentally using the previously obtained values for K+, Ca2+ and H+ binding. Electrostatic attraction was modeled according to Gouy-Chapman theory. Evaluation of parameters was based upon the sorption of ions to PM vesicles suspended in solutions containing variable concentrations of H+, Ca2+ and La3+ or Al3+. Use of small volumes, and improved assay techniques, allowed the measurement of concentration depletions caused by sorption to vesicles. Some independent confirmation of our model is provided by substantial agreement between our computations and two published reports of La3+ effects upon zeta potentials of plant protoplasts. The single published report concerning the electrostatic effects of Al on cell membranes is in essential agreement with the model.

Journal

The Journal of Membrane BiologySpringer Journals

Published: Oct 1, 1997

There are no references for this article.

You’re reading a free preview. Subscribe to read the entire article.


DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy affordable access to
over 12 million articles from more than
10,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Unlimited reading

Read as many articles as you need. Full articles with original layout, charts and figures. Read online, from anywhere.

Stay up to date

Keep up with your field with Personalized Recommendations and Follow Journals to get automatic updates.

Organize your research

It’s easy to organize your research with our built-in tools.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

DeepDyve Freelancer

DeepDyve Pro

Price
FREE
$49/month

$360/year
Save searches from Google Scholar, PubMed
Create lists to organize your research
Export lists, citations
Read DeepDyve articles
Abstract access only
Unlimited access to over
18 million full-text articles
Print
20 pages/month
PDF Discount
20% off