#awk script to only keep polar hydrogens for UHBD

{
if ($3 ~/C/ || $3 ~/O/ || $3 ~/N/ || $3 ~/S/){
	print
} else {

if ($3 == "1H" || $3 == "2H" || $3 == "3H" || $3=="H"){
print
}
if (($4 == "SER" || $4 == "CYS") && ($3 == "HG")){
	print
} 
if ($4 == "THR" && $3 == "HG1"){
print
}
if ($4 == "ASN" && $3 ~/HD/){
	print
}
if ($4 == "LYS" && $3 ~/HZ/){
	print
}
if (($4 ~/ARG/ || $4 ~/TYR/) && ($3 ~/HH/)){
	print
}
if (($4 == "GLN" || $4 == "ARG") && ($3 ~/HE/)){
	print
}
if (($4 == "HIS" && $3 == "HE2") || ($4 == "TRP" && $3 == "HE1")){
	print
}

}

}