@tocheck : Apple Corn Pie Fish
%checkfrom:
Meat => Fish Apple Pork Bacon
Fruit => Apple Pie Orange Beef

##</code><code>##

Meat=> Pork Bacon
Fruit => Orange Beef

##</code><code>##

foreach $checking(@tocheck){
for (keys %checkfrom){
if ($checkfrom{$_} eq $checking){
  #does  
}

##</code><code>##

Activpospf.txt
PF01486
PF00319
PF04947


PFACTest.txt
PF01486 : C12345 C23456
PF00319 : C15234
PF12345 : C00001 C12345
PF98765 : C00000

##</code><code>##


#!/usr/bin/perl
use Modern::Perl;
use File::Slurp qw/read_file write_file/;
my $pfaminput ='Activpospf.txt';
my $seedinput ='PFACtest.txt';
#open POSITIVEOUT, ">", 'ActivPosdata.txt';
#open NEGATIVEOUT, ">", 'ActivNeg.txt';
my %seedin  =map{chomp; /(.+)\s+\:\s+(.+)/;$1=>$2;} read_file $seedinput;

my $pfam;
my @tocheck;
my @negative;
for $pfam(read_file $pfaminput){
	chomp ($pfam);
	if (defined $seedin{$pfam}) {
		my @splitter =split(/ /, $seedin{$pfam});
		push (@tocheck, @splitter);
		delete $seedin{$pfam};}}

##</code><code>##

PF12345 : C00001
PF98765 : C00000