Reduce the gap between arrow and molecule (node) in chemfig scheme

Question

I have the following scheme.

\documentclass[crop,trim]{standalone}
\usepackage{pgfplots}
\usepackage{chemfig}
\usepackage{tikz}
\usetikzlibrary{calc,positioning}
\usepackage{amsmath,amssymb}
\usepackage{mathtools}
\usepackage[sfdefault]{FiraSans}
\usepackage[small]{eulervm}
%\usepackage{opensans}
%\usepackage{mathpazo}

\begin{document}

% Remove margins from tabular. Don't know how it works but see 
% https://tex.stackexchange.com/a/116784/8087
\begin{tabular*}{5cm}{@{}l@{\extracolsep{\fill}}r@{}}
   \schemestart
       X \arrow{->}[0,0.75] X\textsuperscript{*}
   \schemestop\label{reac:phospho}
   \\
   \schemestart
       X\textsuperscript{*} + P \arrow{<->>}[0,0.75]  X\textsuperscript{*}P
       \arrow{->}[0,0.7] X + P
   \schemestop\label{reac:depospho}
\end{tabular*}
\end{document}

I get the following:

There is quite a white-space between node and arrow. I want to reduce this space so that this fits into margin for document. How to reduce this gap?

Answer 1

like this?

i redesign table. now has only one column, not two, and instead tabular* is used tabular. also i made arrows slightly shorter:

\documentclass{standalone}
\usepackage{pgfplots}
\pgfplotsset{compat=1.16}
\usetikzlibrary{calc,positioning}
\usepackage{mathtools,amssymb}
\usepackage[sfdefault]{FiraSans}
\usepackage[small]{eulervm}
\usepackage{chemfig}

\begin{document}

% Remove margins from tabular. Don't know how it works but see
% https://tex.stackexchange.com/a/116784/8087
\begin{tabular}{@{} l @{}}
   \schemestart
X \arrow{->}[0,0.5] X\textsuperscript{*}
   \schemestop\label{reac:phospho}
   \\
   \schemestart
X\textsuperscript{*} + P \arrow{<->>}[0,0.5]  X\textsuperscript{*}P \arrow{->}[0,0.5] X + P%
   \schemestop\label{reac:depospho}
\end{tabular}

as you can see, the preamble is reorganized too. (mathtools load amsmath, and pgfplots load tikz, so it is sufficient to load only the firs packages.