Display Settings:

Format

Send to:

Choose Destination
See comment in PubMed Commons below
Biochim Biophys Acta. 1981 Dec 7;649(2):419-26.

Counterflow efflux of thiamin in Escherichia coli.

Abstract

A resting cell of Escherichia coli lacking thiamin kinase incorporated external thiamin with an energy-dependent counterflow efflux (C-efflux). This C-efflux could be separated frm an energy-dependent exit by a selective inhibition of exit by 2 x 10(-2) M NaN3. The extracellular thiamin could be replaced by thiamin diphosphate, resulting in the same rate of C-efflux, but the rate of C-efflux of intracellular thiamin diphosphate against the external thiamin was markedly low. This low rate of C-efflux of thiamin diphosphate could explain the higher accumulation of the compound than that of free thiamin in the thiamin-kinase-defective mutant as well as in its wild-type parent. Basic characteristics of free thiamin uptake and exit in E. coli W mutant were compared with those reported in K 12 mutant: a marked difference existed in the rate of exit. The low rate of exit in E. coli W 70-23-102 was inferred as the reason for the absence of an overshoot phenomenon of thiamin uptake in this strain.

PMID:
7032593
[PubMed - indexed for MEDLINE]

LinkOut - more resources

Full Text Sources

Molecular Biology Databases

PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Elsevier Science
    Loading ...
    Write to the Help Desk