Abstract
Chemical affinity labeling of pure sterol methyl transferase (SMT) from Saccharomyces cerevisiae using the mechanism-based irreversible inhibitor, [3-3H]26,27-dehydrozymosterol, inhibited the SMT with an apparent K(i) of 1.1 μM and k(inact) of 1.52 min-1. The protein-inhibitor adduct was subjected to cleavage with trypsin and the resulting covalently modified peptide was analyzed by Edman sequencing from the N-terminus. The radiochemically labeled ca. 5.0 kDa peptide fragment of the cleavage mixture was shown to be contiguous through 17 residues to a segment that includes a highly conserved hydrophobic motif (Region I. stretching between T78 and F91) characteristic of SMT enzymes. The results confirm that Region I is the sterol binding/active site.
Original language | English |
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Pages (from-to) | 1533-1536 |
Number of pages | 4 |
Journal | Bioorganic and Medicinal Chemistry Letters |
Volume | 9 |
Issue number | 11 |
DOIs | |
State | Published - Jun 7 1999 |