Pergamon Bioorganic & Medicinal Chemistry Letters, Vol. 7, No. 16, pp. 2125-2130, 1997 © 1997 Elsevier Science Ltd All rights reserved, Printed in Great Britain ,~r,r~.-~ 0..~...~..~_. 0960-894X/97 $17,00 + 0.00 PII: SYNTHESIS AND EVALUATION OF BENZOPHENONE-BASED PHOTOAFFINITY LABELING ANALOGS OF PRENYL PYROPHOSPHATES CONTAINING STABLE AMIDE LINKAGES Tammy C. Turek, Igor Gaon, Dave Gamache and Mark D. Distefano* Department of Chemistry, University of Minnesota, Minneapolis, MN 55455 Abstract: The syntheses of two photoactive prenyl pyrophosphate analogs (la and lb) that incorporate stable amide-linked benzophenones are described. Compound la contains a single isoprene (C5) unit between the pyrophosphate and benzophenone functionalities while lb contains a geranyl (Ci0) moiety. Compounds la and lb are competitive inhibitors of yeast farnesyl protein transferase with respect to farnesyl pyrophosphate and have Kl values of 6000 nM and 700 nM. Upon irradiation, [32p]-lb preferentially labels the 13-subunits of yeast farnesyl protein transferase and human geranylgeranyl protein transferase. © 1997 ElsevierScience Ltd. Protein prenylation is a common post-translational protein modification that involves the attachment of a famesyl (C~5) or geranygeranyl (C20) moiety to a specific protein derived cysteine residue; prenylated proteins have been isolated from animal, plant and fungal sources. ~ The discovery that Ras protein is famesylated and that the isoprenoid is essential for the transforming activity of mutant Ras proteins has generated considerable interest in this area. A number of groups are designing inhibitors of famesyl protein transferase (FPTase) as potential anticancer agents. 2 Photoaff'mity labeling is a useful technique for studying the interactions between small molecules and proteins) To gain information about the interactions between proteins and prenyl pyrophosphates, we have synthesized a number of analogs of famesyl pyrophosphate and geranylgeranyl pyrophosphate that incorporate photoactive benzophenone crosslinking groups. In earlier work, we demonstrated the utility of benzophenone-containing analogs by showing that they are potent competitive inhibitors of yeast FPTase (yFPTase), they irreversibly inactivate yFPTase upon photolysis, and they preferentially label the 13-subunit of yFPTase. 4' 5 This paper describes the preparation and use of new analogs shown in Figure 1 (la and lb) that replace the ester linkages that coupled the benzophenone units to the isoprenoids in earlier compounds with more stable amide linkages. 9 9 Farnesyl Pyrophosphate (FPP) C~~ H O O ~...L .... ;~o ~ v ~v -0~, " ~''0 O_ O_ - O O la h 11 o o O~o-P-o-P- o L Jn O_ O_ - 0 0 2a n=O 2b n=l Figure 1 / / / / o o P. P~ "~ "-. ~ o', o'-o O_ O_ - Geranylgeranyl Pyrophosphate (GGPP) P P II II O_ O_ - 0 0 lb o P P 0 ~ "0 ~ "0 O_ O_ - 0 lc 2125