Skip Navigation

This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Request Permissions
Google Scholar
Right arrow Articles by HIRATA, H.
Right arrow Articles by KAGAWA, Y.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by HIRATA, H.
Right arrow Articles by KAGAWA, Y.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

J. Biochem, 1976, Vol. 79, No. 6 1157-1166
© 1976 Japanese Biochemical Society

research-article

Active Transport of Alanine by Thermostable Membrane Vesicles Isolated from a Thermophilic Bacterium1

Hajime HIRATA, Nobuhito SONE, Masasuke YOSHIDA and Yasuo KAGAWA

Department of Biochemistry, Jichi Medical School, Minamikawachi-machi Kawachi-gun, Tochigi 329-04

1. Thermostable membrane vesicles which were capable of active transport of alanine dependent on either respiration or an artificial membrane potential were isolated from the thermophilic aerobic bacterium PS3.

2. Uptake of alanine was dependent on the oxidation of ascorbate-phenazine metho-sulfate or on generated or exogenous NADH, but succinate and malate failed to drive the uptake. The optimum temperature for respiration-driven uptake of alanine was 45 to 60°.

3. Potassium ion-loaded vesicles were prepared by incubating vesicles at 55° in 0.5 M potassium phosphate. The addition of valinomycin elicited rapid and transient uptake of alanine under the test conditions. Uptake of alanine in response to valinomycin was progressively enhanced by the addition of dicylohexylcarbodiimide, but was completely abolished in the presence of a proton conductor or synthetic permeable cation. The effect of dicyclohexylcarbodiimide was dependent on its concentration and was maximal at a concentration of 0.4 mM.

4. The proton permeability of membrane vesicles was reduced by the addition of dicyclohexylcarbodiimide. A small but significant difference was found in the initial rates of proton uptake in the presence of dicyclohexylcarbodiimide with and without alanine. The results suggest that protons alanine are transported simultaneously in a stoichiometric ratio of 1: 1.

5. The uptake of alanine was also driven by a pH gradient induced by an instantaneous pH drop in a suspension of alkali-loaded vesicles. Thus, alanine accumulation was driven not only by an electrical potential but also by a pH gradient.

6. Addition of ATP resulted in the inhibition of alanine uptake dependent on artificial membrane potential. ATP hydrolysis by membrane ATPase created a membrane potential which was inside-positive, and this might decrease the effective membrane potential (generated by K+ efflux mediated by valinomycin) available to drive alanine uptake.

1This work was supported by grants from the Ministry of Education, Science and Culture, of Japan, the Matsunaga Memorial Fund and the Toray Science Foundation.


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?




Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.