use strict;
use warnings;

my $str1 = q{PF01389	6	218	1	255	430.09};
my $str2 = q{PF00691	PF01389};

my %str1Hash = map {$_ => 1} split m{\s+}, $str1;

foreach my $possible (split m{\s+}, $str2)
{
    print qq{$possible common\n}
       if exists $str1Hash{$possible};
}