#!/usr/bin/perl

use strict;
use warnings;

my %data;

open (SHIFTS,"file1.txt") or die;
open (PDB, "file2.txt") or die;

while (my $line = <PDB>) {
    chomp $line;
    my @fields = split(/\t/,$line);
    $data{$fields[4]} = $fields[2];
 }

 close PDB;

 while (my $line = <SHIFTS>) {
    chomp($line);
    my @columns = split(/\t/,$line);
    my $value = ($columns[1] =~ m/^.*?([A-Za-z])/ );
 }
 if (my $value = $data{"$_"})
    print "$columns[0]\t$fields[3]\t$value\t$data{$value}\n";

 close SHIFTS;
 exit;