sub parse_pdb() {
	
	my $file = shift;

	my %hash_pdb = ();

	# Opening of PDB file after dowloading	
	open(FH, $file);
	@atomrecord = <FH>;
	
	foreach my $record (@atomrecord) 
	{   
		chomp($record);
		if($record =~/^ATOM/) {	   
			@temp      = split(/\s+/, $record);
			$con_key   = "";
			$con_key   = "$temp[3]"." "."$temp[4]";
			$count = 0;
			
			if( $hash_pdb{$con_key} ) {
				if($val_seen{$temp[5]}) { }
				else {
					$hash_pdb{$con_key} = $hash_pdb{$con_key}."\t"."$temp[5]"; 
				}
			}
			else {
				$hash_pdb{$con_key} = $temp[5];
			}
			$val_seen{$temp[5]} = 1; 
		 }
		if($record =~ /^ENDMDL/){
			print "i am going out of loop\n";
			last;
		}
		
	}
	return \%hash_pdb;
}