Question

Explain the significance of the observation that peptides such as fMet-Leu-Phe "activate" the phagocytotic (particle-engulfing) functions of mammalian leukocytes (white blood cells).

Short answer

The peptides such as fMet-Leu-Phe "activate" the phagocytotic functions of mammalian leukocytes as fMet is presnet in the newly synthesized bacterial peptide, which indicates the invasion of bacteria.

Step-by-step solution

Definition of Concept

As a powerful polymorphonuclear leukocyte (PMN) chemotactic factor and macrophage activator, N-Formylmethionyl-leucyl-phenylalanine (fMLF, fMLP, or N-formyl-met-leu-phe) is an N-formylated tripeptide.

Explain the significance of the observation

The presence of fMet (formyl-methionine) in the system indicates the presence of invading bacteria because only newly synthesized bacterial polypeptides have fMet at their N-terminus. Phagocytosis can be used by leukocytes that recognize the fMet residue to eliminate these bacteria.