123951-88-2 AIDS-001226 AIDS001226 H-.alpha.-Aminobutyric acid-.alpha.-Aminobutyric acid-Asn-Tyr-Thr-OH H-Abu-Abu-Asn-Tyr-Thr-OH L-Threonine, L-2-aminobutanoyl-L-2-aminobutanoyl-L-asparaginyl-L-tyrosyl-