FK 565 [ FK-565,FR 41565,FR-41565,heptanoyl-gamma-D-glutamyl-L-meso-diaminopimelyl-D-alanine ] synthetic cpd; also immunoactive peptide isolated from Streptomyces active against multiplication of HSV-1 & HSV-2 virus; RN refers to (D-Ala-D-Glu-erythro-L)-isomer; structure in first source