#! /usr/bin/perl
use strict;
use warnings;
use feature qw{ say };

open my $in, '<', shift or die $!;

local $/ = '>';
while (my $record = <$in>) {
    next if '>' eq $record;  # Skip the "0th empty record".

    my ($header, $data) = split /\n/, $record, 2;
    $data =~ s/\n//g;
    say "Found in $header" if -1 != index $data, 'CDECGKEFSQGAHLQTHQKVH';
}