THE KINETICS OF PENETRATION : XII. HYDROGEN SULFIDE
1Laboratories of The Rockefeller Institute for Medical Research, New York and The Bermuda Biological Station for Research, Bermuda.
The Journal of General Physiology
|October 30, 2009
Summary
Hydrogen sulfide (H(2)S) enters Valonia macrophysa cells proportionally to its molecular concentration. This differs from ammonia and guanidine uptake, suggesting H(2)S diffuses through the cell
Area of Science:
- Plant Physiology
- Cell Biology
- Biochemistry
Background:
- Investigating solute transport across cell membranes is crucial for understanding cellular function.
- Previous studies on ammonia and guanidine transport show non-linear uptake rates.
- Valonia macrophysa, a large marine alga, serves as a model organism for cell physiology research.
Purpose of the Study:
- To determine the mechanism and kinetics of hydrogen sulfide (H(2)S) uptake in Valonia macrophysa cells.
- To compare the transport characteristics of H(2)S with those of other weak bases like ammonia.
Main Methods:
- Measurement of H(2)S and total sulfide concentrations in the external solution and cell sap over time.
- Varying external molecular H(2)S concentrations to observe uptake rates.
- Comparison of H(2)S uptake kinetics with previously published data for ammonia and guanidine.
Main Results:
- The rate of total sulfide (H(2)S + S(-)) uptake into the sap was proportional to the external molecular H(2)S concentration for up to 5 minutes.
- This linear relationship contrasts with the saturating uptake kinetics observed for ammonia and guanidine.
- The data supports the hypothesis that H(2)S enters cells via diffusion of molecular H(2)S across the protoplasmic surface.
Conclusions:
- Hydrogen sulfide uptake in Valonia macrophysa primarily occurs through the diffusion of its molecular form.
- The transport mechanism for H(2)S differs significantly from that of ammonia and guanidine.
- Further investigation is needed to explain deviations from simple monomolecular diffusion kinetics for H(2)S.
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