1887

Abstract

Multiple transport systems for L-aspartic acid exist in The intracellular accumulation of L-aspartate against a concentration gradient was immediately inhibited by proton conductors, such as carbonyl cyanide -trifluoromethoxyphenyl-hydrazone, 2,4-dinitrophenol or nigericin. Transport activity was gradually lost when inhibitors of protein synthesis were added. L-Aspartate transport had two pH optima at 6.5 and 4.5. At pH 6.5, two saturable transport components with different and values could be resolved by kinetic studies. A high-affinity system (system I) preferred the L-isomers of the anionic forms of aspartic and glutamic acid. At the same pH, a second, low-affinity system (system II) operated, which was presumably less specific than system I and also able to accept, at high concentrations, neutral amino acids. At pH 4.5, the Lineweaver-Burk plot revealed only a single catalytic component, with and values similar to those of system II. Again, in contrast to system I, this component showed high affinity for neutral amino acids. The data suggest that L-aspartic acid and L-glutamic acid are transported by this system as neutral zwitterionic molecules.

Loading

Article metrics loading...

/content/journal/micro/10.1099/00221287-103-2-307
1977-12-01
2019-10-14
Loading full text...

Full text loading...

http://instance.metastore.ingenta.com/content/journal/micro/10.1099/00221287-103-2-307
Loading
This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error