121197-29-3 AIDS-000525 AIDS000525 H-.alpha.-Aminobutyric acid-Thr-Asn-Tyr-Thr-OH H-Abu-Thr-Asn-Tyr-Thr-OH L-Threonine, 2-aminobutanoyl-L-threonyl-L-asparaginyl-L-tyrosyl-