amino acids, the peptide bond, protein primary structure

Alpha amino acids

have a primary amino group (-NH2) as a substituent of the alpha carbon atom

alpha carbon

carbon next to the carboxylic group

formation of a dipeptide

a CO-NH bond is made with H2O elimination

disulphide bonded cysteines 

forms when 2 thiol groups are oxidised 

amino acid function

chemical messengers for communication between cells

GABA

glutamine decarboxylation product and dopamine a tyrosine derivative - neurotransmitters

Histamine

decarboxylation product of histidine 

Thyroxine

tyrosine derivative - hormone