\documentclass[12pt,border=3pt,tikz,class=scrartcl,multi=false]{standalone}
\usepackage{times}
\usepackage[T1]{fontenc}
\usepackage[latin1]{inputenc}
\usepackage{mathtools,amssymb,gensymb}
\usepackage{pgfplots}
\pgfplotsset{compat=1.12}
\usetikzlibrary{positioning,calc,arrows,fit,backgrounds,decorations.text,shapes}
\usepackage{chemfig,chemmacros}
\renewcommand*{\familydefault}{\sfdefault}
\renewcommand*\printatom[1]{\ensuremath{\mathsf{#1} } }
\setatomsep{2.5em}
\setdoublesep{.6ex}
\setarrowdefault{,1,ultra thick}
\setbondstyle{very thick,cap=round}
\definesubmol\nobond{-[0,.6,,,draw=none]}
\usepackage[american]{circuitikz}
\pagestyle{empty}
\thispagestyle{empty}
\begin{document}
\renewcommand{\baselinestretch}{1}
\begin{tikzpicture}[thick, >=latex']
\node (n1) {\chemname{\chemfig{
\chemabove[0pt]{N}{\fpch}H_3-[6]-[::60]-[::-60]-[::60]-[::-60,,,,dash pattern=on 2pt off 2pt]
} } {lysine} };
\node [right=2 of n1.south east,anchor=south] (n2) {\chemname{\chemfig{
\chemabove[0pt]{N}{\fpch}H_2(-[3])-[6]-[::60]-[::-60]-[::60]-[::-60,,,,dash pattern=on 2pt off 2pt]
} } {methyllysine} };
\node [right=of n2] (n3) {\chemname{\chemfig{
\chemabove[0pt]{N}{\fpch}H(-[3])(-[5])-[6]-[::60]-[::-60]-[::60]-[::-60,,,,dash pattern=on 2pt off 2pt]
} } {dimethyllysine} };
\node [right=of n3] (n4) {\chemname{\chemfig{
\chemabove[0pt]{N}{\fpch}(-[3])(-[5])(-[7])-[6]-[::60]-[::-60]-[::60]-[::-60,,,,dash pattern=on 2pt off 2pt]
} } {trimethyllysine} };
\end{tikzpicture}
\end{document}