PMID-sentid Pub_year Sent_text comp_official_name comp_offsetprotein_name organism prot_offset 19022679-3 2009 The lactone ring size was found to be critical, as C21 to C19 translactonisation to afford 20-membered isodictyostatin analogues led to a significant loss of cytotoxicity. Lactones 4-11 TBL1X/Y related 1 Homo sapiens 51-54 6302244-3 1983 This finding, together with X-ray crystallographic data from a separate study on the minor epimer, establishes the C20 configuration of the minor epimer as S and of the major epimer as R. NMR evidence indicates that the average lactone rotamer for the minor epimer has the C22 position located on the C12 side of the steroid nucleus, whereas the average lactone rotamer for the major epimer has the C21 position located on the C12 side of the steroid nucleus. Lactones 228-235 TBL1X/Y related 1 Homo sapiens 399-402