Our objective was to evaluate the maternal-fetal transfer of melatonin in pregnant women. Serum melatonin concentration was measured by high-performance liquid chromatography with electrochemical detection in a maternal vein and in the umbilical artery and umbilical vein at the time of birth. Blood samples were obtained from 12 women who had spontaneously delivered vaginally at night. A single oral dose of melatonin was administered to each of 33 patients who underwent a cesarean section, and, blood samples were taken at 1, 2, 3, or 4 hr after the administration of melatonin at delivery. Cesarean section was performed between 1300 and 1500 hr. The mean melatonin concentrations of melatonin in maternal peripheral venous blood and umbilical arterial and umbilical venous blood did not differ significantly, and positive correlations in the serum levels of melatonin were observed between the three sources of blood. The oral administration of 3 mg of melatonin to pregnant women led to marked increases in the serum levels of melatonin, with maximum levels observed 2 hr (21.84 +/- 2.09 ng/ml) after drug administration. Changes in serum levels of melatonin in the umbilical vein and artery resembled those found in the maternal vein. Serum melatonin concentrations did not differ significantly between the maternal vein and the umbilical veins. Serum levels of melatonin in the umbilical vein after the administration of melatonin were significantly and closely correlated with those in the maternal vein (r = 0.924, P < 0.001). These results suggest that, in humans, melatonin is transferred from the maternal to the fetal circulation both easily and rapidly. A potential for the therapeutic use of melatonin as an antioxidant exists in the patients with preeclampsia.

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Cytochrome P450cam (CYP101) of Pseudomonas putida PpGl in which Arg112 is substituted by Cys was isolated by in vitro random mutagenesis of the camC gene DNA coding for P450cam. The absorption spectra of the purified mutant enzyme were similar to those of the wild type enzyme, but its substrate‐dependent NADH oxidation activity in the presence of putidaredoxin (Pd) and putidaredoxin reductase (PdR) was extremely low. The rate constant of electron transfer from reduced Pd to the heme of the mutant P450cam, measured on an anaerobic stopped flow apparatus, was 1/400 of that of the wild type enzyme and the dissociation constant of the mutant P450cam for oxidized Pd was several fold higher than that of the wild type enzyme. A considerable decrease in mid‐point potential of the mutant enzyme was also noted. We conclude that Arg112, which is located on the surface of the P450cam molecule and hydrogen‐bonded to one of the heme propionate chains, plays an essential role in the electron transfer from Pd.

The gene encoding aromatase P-450 (CUP XIX) has been isolated from two types of human genomic DNA libraries. It spans at least 70 kb and consists of 10 exons. The translational initiation site and the termination site are located in exon 2 and exon 10, respectively. The promoter region of the gene contains a TATA box, a CAAT box and two putative AP-1 binding sites beginning at -28, -83, -55 and -68 bp, respectively, from the transcriptional initiation site. In addition, a palindromic nucleotide sequence is observed between -209 and -196 and two types of repetitious hexanucleotide (consensus : AATGAA and CCATh$) are also present within the regions between -485 and -433 and between -358 and -331. Transient expression studies of chloramphenicol acetyltransferase constructs bearing various lengths of 5'-flanking region of the gene show that the region between -500 and -243 contains negative cis-acting element(s), whereas the region between -242 and -183 is required for efficient transcriptional activity. Northern blot analysis demonstrates that the expression of aromatose P-450 gene is remarkably stimulated by treatment of cells with 12-0-tetradecanoyl-phorbol 13-acetate. By chloramphenicol acetyltransferase assay the region up to nucleotide position -242 relative to the transcriptional initiation site is shown to participate in the transcriptional responsiveness to this phorbol ester.Human aromatase P-450 is the product of CYP XIX gene More recently several groups, including ours, reported the isolation and nucleotide sequence of cDNA clones encoding aromatase P-450 by screening cDNA libraries with synthetic oligonucleotides designed on the basis of the amino acid sequence of the enzyme [19,20] or antibodies against the purified enzyme [21,22]. Our previous studies also demonstrated that Correspondence to Y. Shizuta,