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Ricin - inhibitor design. Annual report, 15 April 1994-14 April 1995

Technical Report ·
OSTI ID:191508
Substrates for ricin A-chain include short RNA stem-loop structures which have been synthesized with radioactive labels for ease of catalytic assay and for kinetic isotope effects. Ricin A-chain from several sources is incapable of completing multiple catalytic cycles using these substrates. A family of ricin substrate analogue molecules have been synthesized and tested which are specific for transition states with oxycarbonium character or for enzymatic mechanisms involving protonation of the adenine leaving group. Formycin analogues were incorporated into RNA oligomeric structures and tested for binding to ricin A-chain or as inhibitors of the ricin-inactivation of in vitro translation using rabbit reticulocyte lysates. Ribo-oxycarbonium ion analogues containing iminoribitol analogues of ribose were synthetically incorporated into RNA oligomeric structures. Neither formycin nor ribo-oxycarbonium analogues, either singly or in RNA oligomers caused significant inhibition of ricin A-chain when assayed in reticulocyte lysate translation assays. The results indicate a novel transition state mechanism for ricin A-chain, or a requirement for additional features of 28s rRNA to bind transition state analogues.
Research Organization:
Albert Einstein Coll. of Medicine, Bronx, NY (United States)
OSTI ID:
191508
Report Number(s):
AD-A--299338/4/XAB; CNN: Contract DAMD17-93-C-3051
Country of Publication:
United States
Language:
English

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