Open AccessRelationship of a Membrane-Bound D-(-)-Lactic Dehydrogenase to Amino Acid Transport in Isolated Bacterial Membrane Preparations
Author(s) -
H. Ronald Kaback,
Larry Milner
Publication year - 1970
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.66.3.1008
Subject(s) - biochemistry , amino acid , alanine , valine , aspartic acid , leucine , methionine , amino acid synthesis , phenylalanine , glycine , chemistry , isoleucine , tryptophan , serine , lactic acid , histidine , cysteine , biology , lysine , bacteria , enzyme , genetics
The conversion of D-lactate to pyruvate in isolated membrane preparations ofE. coli ML 308-225 markedly stimulates the transport of proline, glutamic acid, aspartic acid, aspargine, tryptophan, lysine, serine, alanine, and glycine. The uptake of histidine, phenylalanine, tyrosine, leucine, isoleucine, and valine by the membranes is also markedly stimulated by this conversion, although these amino acids are taken up much less effectively than those mentioned previously. The uptake of arginine, methionine, cystine, and cysteine is enhanced only about twofold in the presence of D-(-)-lactate, and these amino acids are not concentrated well by the membranes. With the exception of glutamate, asparate, asparagine, and methionine, which are converted to other metabolites to varying extents in the intramembranal pool, each of the other amino acids was recovered from the membranes as the unchanged amino acid. Succinate, L-(+)-lactate, D,L-α-hydroxybutyrate, and DPNH partially replace D-(-)-lactate but are less effective.