123951-84-8 AIDS-000527 AIDS000527 H-.alpha.-Aminobutyric acid-Thr-Asn-Tyr-Thr-NH2 H-Abu-Thr-Asn-Tyr-Thr-NH2 L-Threoninamide, L-2-aminobutanoyl-L-threonyl-L-asparaginyl-L-tyrosyl-