PEPTIDES

amide bonds

Peptides and proteins are formed when amino acids are joined together by

dipeptide

has two amino acids joined together by one amide bond.

peptide bond

The amide bond is called a

tripeptide

has three amino acids joined together by one amide bond.

Polypeptides

have many amino acids, while proteins have more than 40 amino acids.

N-terminal

The amino acid with the free –NH3+ group is the _________ amino acid and is written on the left.

C-terminal

The amino acid with the free –COO− group is the _________ amino acid and it written on the right.

Enkephalins

pentapeptides made in the brain, act as pain killers and sedatives by binding

to pain receptors.

morphine and heroin

Addictive drugs __________ and ________ bind to these same pain receptors (enkephalins) , thus producing a similar physiological response, though longer lasting

endorphins

Enkephalins belong to the family of polypeptides called _______, which are known for their pain reducing and mood enhancing effects.

Oxytocin and vasopressin

are cyclic nonapeptide hormones, which have identical sequences except for two amino acids.