1. The complete amino acid sequence of the Zn2+-containing D-alanyl-D-alanine-cleaving carboxypeptidase of streptomyces albus G
B Joris, J Van Beeumen, F Casagrande, C Gerday, J M Frère, J M Ghuysen Eur J Biochem. 1983 Jan 17;130(1):53-69. doi: 10.1111/j.1432-1033.1983.tb07116.x.
The 22076-Mr Zn2+-containing D-alanyl-D-alanine-cleaving carboxypeptidase of Streptomyces abuls G effectively catalyses the transfer of the N alpha, N epsilon-diacetyl-L-lysyl-D-alanyl electrophilic group of the standard tripeptide substrate N alpha, N epsilon-diacetyl-L-lysyl-D-alanyl-D-alanine to water. It also performs a weak beta-lactamase activity, hydrolysing penicillin into penicilloate at a very low rate. This protein consists of 212 amino acid residues in a single polypeptide chain. The N terminus is partially blocked as a result of the cyclization of the dipeptide Asn-Gly into anhydroaspartylglycine imide. The protein has been fragmented by cyanogen bromide into five fragments whose sequences have been determined via appropriate subcleavages with various proteases. The ordering of the cyanogen bromide peptide fragments has been carried out (a) by submitting the S-carboxymethylated protein to complete tryptic digestion and labelling the methionine-containing peptides thus obtained with iodo[14C]-acetamide, and (b) by submitting to limited tryptic digestion the S-[2-(4'-pyridyl)ethyl]-cysteine protein whose amino groups have been blocked by reaction with exo-cis-3,6-endoxo-delta 4-tetrahydrophthalic anhydride prior to digestion. The protein contains six cysteine residues in the form of three disulfide bridges. No homology is found by comparing this peptidase with other Zn2+-containing enzymes (carboxypeptidase A, thermolysin, carbonic anhydrase B and alcohol dehydrogenase) and several completely or partially sequenced, serine-containing D-alanyl-D-alanine-cleaving peptidases and Zn2+/serine-containing beta-lactamases.
2. Phase I and pharmacokinetic trial of the proapoptotic sulindac analog CP-461 in patients with advanced cancer
Weijing Sun, James P Stevenson, James M Gallo, Maryann Redlinger, Daniel Haller, Kenneth Algazy, Bruce Giantonio, Hector Alila, Peter J O'Dwyer Clin Cancer Res. 2002 Oct;8(10):3100-4.
CP-461 is a member of a class of novel proapoptotic drugs that specifically inhibit cyclic GMP phosphodiesterases but not cyclooxygenase-1 or -2. CP-461 inhibits the growth of a broad range of human tumor cell lines in vitro at micromolar concentrations and selectively induces apoptosis in cancer cell lines but not normal cells. Preclinical studies revealed good oral bioavailability and no toxicity in dogs and rats at single doses up to 500 mg/kg. In a Phase I trial, 21 patients with a range of solid tumors and good performance status received CP-461 p.o. twice daily for 28 consecutive days. Cycles were repeated without a treatment-free interval. CP-461 doses ranged from 100 to 800 mg/day. Therapy was well tolerated overall, and a maximum tolerated dose was not reached. Grade 3 asymptomatic aspartate aminotransferase/alanine aminotransferase elevation in 1 patient treated at 800 mg/day was the only dose-limiting toxicity. No hematologic toxicity was noted. Peak plasma concentrations occurred between 1 and 2 h after dosing, and doses above 200 mg/day exceeded the known in vitro EC(50) (1-2 micro M) for apoptosis in cancer cells. No drug was detectable after 24 h of administration, and the terminal half-life was 6.7 h. The area under the plasma concentration-time curve was dose-proportional from 200 to 800 mg/day. Four patients exhibited disease stability after two cycles of treatment. CP-461 is minimally toxic at doses up to 800 mg/day when administered p.o. on a twice-daily schedule.
