New ribosome-inactivating proteins from seeds and fruits of the bitter gourd Momordica charantia

A new ribosome-inactivating protein (RIP) (delta-momorcharin) and a candida te RIP (epsilon-momorcharin) were isolated, respectively, from the seeds an d fruits of the bitter gourd Momordica charantia, by affinity chromatograph y on Affigel blue gel and ion exchange chromatography on Mono S with a fast protein liquid chromatography (FPLC) system. Both delta- and epsilon-momor charins were adsorbed on Affi-gel blue gel and were eluted from the cation exchange Mono S column earlier than alpha- and beta-momorcharins, the two p reviously reported RIPs, delta- and epsilon-momorcharins possessed a molecu lar weight of 30 and 24 kDa respectively and inhibited cell-free translatio n in rabbit reticulocyte lysate with an IC50 Of 0.15 and 170 nM, The sequen ce of the first seven N-terminal amino acids in delta-momorcharin was DVNFG LA, which was different from the N-terminal sequences DVSFRLS and DVNFDLS f or alpha- and beta-momorcharins respectively. (C) 1999 Elsevier Science Ltd . All rights reserved.