assimilates peptides and hydrolyses them with intracellular peptidases. Amino acid auxotrophs ( or ) grew on a variety of di-and tripeptides up to twice as slowly as with free amino acids. has separate uptake systems for both dipeptides and oligopeptides (three or more residues). Although the dipeptide system transported a variety of structurally diverse dipeptides it did not transport peptides having either unprotonatable N-terminal amino groups, blocked C-terminal carboxyl groups, D-residues, three or more residues, -methylated peptide bonds, or β-amino acids. Oligopeptide uptake lacked amino acid side-chain specificity, required a free N-terminal L-residue and had an upper size limit. Glycylglycyl-D, L--fluorophenylalanine inhibited growth of Uptake of glycylglycyl[I-C]alanine was rapid and inhibited by 2,4-dinitrophenol. Both dipeptide and oligopeptide uptake were constitutive. Dipeptides competed with oligopeptides for oligopeptide uptake, but oligopeptides did not compete in the dipeptide system. Final bacterial yields were 5 to 10 times greater when was grown on histidyl di-or tripeptides rather than on free histidine because the histidyl residue was protected from catabolism by L-histidine ammonia-lyase.

Methionine peptides could satisfy the methionine requirements of Generation times on glycylmethionine and glycylmethionylglycine were equal to those obtained with free methionine. Methionylglycylmethionylmethionine gave a generation time twice that of free methionine. Growth of was inhibited by glycylglycyl-D, L--fluorophenylalanine.


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month Most Cited RSS feed

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