The inhibitor profiling of the caspase family of proteases using substrate-derived peptide glyoxals.
A series of substrate-based α-keto-β-aldehyde (glyoxal) sequences have been synthesised and evaluated as inhibitors of the caspase family of cysteine proteases. A number of potent inhibitor sequences have been identified. For example, a palmitic acid containing sequence pal-Tyr-Val-Ala-Asp-glyoxal was demonstrated to be an extremely effective inhibitor of caspase-1, inhibiting not only the action of the protease against synthetic fluorogenic substrates (K(i)=0.3 nM) but also blocking its processing of pro-interleukin-1beta (pro-IL-1β). In addition, the peptide Ac-Asp-Glu-Val-Asp-glyoxal, which is based on the consensus cleavage sequence for caspase-3, is a potent inhibitor of this protease (K(i)=0.26 nM) yet only functions as a comparatively modest inhibitor of caspase-1 (K(i)=451 nM). Potent inhibitor sequences were also identified for caspases-6 and -8. However, the degree of discrimination between the family members is limited. The ability of Ac-Asp-Glu-Val-Asp-glyoxal to block caspase-3 like activity in whole cells and to delay the development of apoptosis was assessed. When tested against caspase-3 like activity in cell lysates, Ac-Asp-Glu-Val-Asp-glyoxal displayed effective inhibition similar to that observed against recombinant caspase-3. Treatment of whole cells with this potent caspase-3 inhibitor was however, not sufficient to significantly stall the development of apoptosis in-vitro.
School of Pharmacy, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK.
Diarmaid J
DJ
Murphy
Brian
B
Walker
Ciara A
CA
Ryan
S Lorraine
SL
Martin
D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D006037:Glyoxal / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D006367:HeLa Cells; D006801:Humans; D019410:Interleukin-16 / Q000378:metabolism; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D011498:Protein Precursors / Q000378:metabolism
D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D019410:Interleukin-16; D010455:Peptides; D011498:Protein Precursors; C105950:interleukin 16 precursor; D006037:Glyoxal