use LWP;
use HTTP::Request::Common;

my $ua = new LWP::UserAgent;
    
my $result = $ua->request(GET 
"http://www.ncbi.nlm.nih.gov/entrez/viewer.fcgi?db=protein&qty=1&start=1&list_uids=148261691&dopt=fasta");

if($result->is_success){
    $fasta = $result->content;
}

# then parse $fasta to get out just my protein sequence