% amino acid general structure (see Jacaranda p.328)
- \chemfig{\color{red}N(-[:135]H)(-[:225]H)-[:-45]C(-[:-90]\color{yellow}\textit{R})(-H)-[:45]\color{blue}C(=[:90]O)-OH}
+ \chemfig{{\color{red}N}(-[:135,,,,red]{\color{red}H})(-[:225,,,,red]{\color{red}H})-[:-45]C(-[:-90]\color{orange}\textit{R})(-H)-[:45]{\color{blue}C}(=[:90,,,,blue]{\color{blue}O})-[,,,,blue]{\color{blue}OH}}
\subsection*{Zwitterions}