Similarities and differences between the peptide transmitters/co-transmitters

Similarities and differences between the peptide transmitters/co-transmitters

 Both neurotransmitters and peptides show high specificity for their specific receptors.
 Neurotransmitters produce physiological responses in nano- or micromolar (1079 to 1076) concentrations, whereas peptides are active in picomolar (10712) concentrations.
 Neurotransmitters bind to their receptors with high affinity but low potency, whereas peptides bind with very high affinity and high potency.
 Neurotransmitters are synthesized at a moderate rate in the nerve terminal,whereas the rate of synthesis of peptides is probably very low.
 Neurotransmitters are generally of low molecular weight (200 or below) whereas peptides are of intermediate molecular weight (1000 to 10 000 or occasionally more).