Peptides

Essential	R	3 letters
isoleucine	(S)-sec-butyl	Ile
leucine	isobutyl	Leu
lysine	4-aminobutyl	Lys
methionine	2-(methylsulfanyl)ethyl	Met
phenylalanine	benzyl	Phe
threonine	(R)-1-hydroxyethyl	Thr
tryptophan	3-indolylmethyl	Trp
valine	isopropyl	Val