documentclass[]{article}

usepackage{amsmath}

setlength{jot}{10pt}

newcommand{an}[1]{langle #1 rangle}

begin{document}

begin{align}
begin{split}
A(1^-6^-5^+2^+4^+3^-) & = frac{an{13}^3an{23}}{an{12}an{24}an{43}an{31}}frac{an{12}}{an{16}an{65}an{52}}biggl( \
& hspace{-0.8in} frac{langle2|6|1]}{langle2|5+6|1]}frac{an{26}^2}{(p_2+k_5+k_6)^2}frac{[12]}{an{12}}%frac{an{56}}{[56]}
+ frac{langle2|5|1]}{langle2|5+6|1]}frac{[15]^2}{(p_1+k_5+k_6)^2}frac{an{16}}{[16]}
biggr)end{split} \
begin{split} & = A(1^-2^+4^+3^-)frac{an{12}}{an{16}an{65}an{52}}biggl( \
& hspace{-0.5in} frac{1}{langle2|5+6|1]}frac{an{26}^3}{(p_2+k_5+k_6)^2}+ frac{langle2|5|1]}{langle2|5+6|1]}frac{[15]^2}{(p_1+k_5+k_6)^2}frac{an{16}}{[16]}
biggr)end{split}
end{align}

end{document}