The binding of a series of alkyl aryl sulfides to chloroperoxidase (CPO) and horseradish peroxidase (HRP) has been investigated by optical difference spectroscopy, circular dichroism, paramagnetic NMR spectroscopy, and NMR relaxation measurements. The data are consistent with binding of the sulfides in the distal side of the heme pocket with CPO and near the heme edge with HRP. A linear correlation between the binding constants of para-substituted sulfides to CPO and the Taft sigma I parameter suggests that these substrates act as donors in donor-acceptor complexes involving some residue of the protein chain. Spectral studies during turnover show that high enantioselectivity in the CPO-catalyzed oxidation of sulfides results from a reaction pathway that does not involve the accumulation of compound II enzyme intermediate.

The study was carried out to determine the concentrations of cefodizime (single 2-g intravenous [i.v.] dose) and ceftriaxone (single 2-g i.v. dose) in the sera and bones of 42 patients (18 women and 24 men) undergoing hip arthroplasty. The concentrations of cefodizime and ceftriaxone in cancellous and cortical bone appear to be related to the free levels in serum but not to the total levels in serum, so the concentrations of cephalosporins in bone must be compared with the free concentrations in serum. Both drugs diffuse well into bone, with concentrations exceeding the MIC at which 90% of the major pathogenic infecting organisms are inhibited.

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