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Absorption and magnetic circular dichroism (MCD) spectra have been obtained for the ferrous carbonyl adducts of cytochromes P-450 and P-420 as well as synthetic model systems. Ferrous porphyrins with sodium methyl mercaptide and CO in benzene give MCD and absorption spectra which are almost identical to those of the natural enzyme, indicating that in P-450 a mercaptide serves as the fifth ligand in the ferrous carbonyl adduct. MCD spectra of models with either propyl mercaptan or N-methylimidazole as the axial ligand are identical with that of P-420. Thus, no unambiguous assignment of the axial ligand can be made in this case. The infrared stretching frequencies of ferrous porphyrin carbonyl complexes and the absorption spectrum of the CO adduct of Na[Fe1(meso-tetraphenylporphyrin dianion)] are consistent with the concept that in P-450 considerable electron density is transferred to the iron by the mercaptide ligand.

The two long chain fatty acids common in marine demosponges, (5Z, 9Z)-5,9-hexacosadienoic (Δ 5,9-26:2) and (5Z, 9Z, 19Z)-5,9,19-hexacosatrienoic (Δ5,9,19-26:3) acids), were identified also as the major phospholipid components in the freshwater sponge Ephydatia fluviatilis. Whereas the typical marine sponge Microciona proliferabiosynthesizes the Δ5,9,19-26:3 acid solely by homologation of exogenous palmitoleic acid (Δ9-16:1) and subsequent desaturation at positions 5 and 9, it was found that the freshwater sponge could further desaturate the Δ5,9-26:2 acid to the triene, indicating for the first time the existence of Δ19-desaturase activity in a living organism.

13C/12C ratios of sets of compounds, algal sterols and terpenes, isolated from dinoflagellate symbiont (zooxanthellae)-bearing soft corals and gorgonians were determined. In most cases, a significant difference was found between the delta 13C values of the terpenes and of the algal sterols from the same set, the algal sterols containing less 13C than the terpenes. These results can only be explained if terpenes are synthesized by the host. Cultured zooxanthellae, isolated from symbiotic associations, do not make terpenes. Algal sterols of the various sets do not all have the same delta 13C value: average values range from -18.2 to -24.3%. A consistent difference of about 7% in the delta 13C values of sterols of cultured symbionts isolated from two of the gorgonians was found. This has potential applications for the taxonomy of zooxanthellae, most of which are believed by some specialists to be one discrete species.

Die Massenspektren einer Reihe monocyclischer Ketone sind gemessen worden. Durch Vergleich der Spektren mit denen deuterierter Derivate ist es möglich, plausible Mechanismen für die Bildung charakteristischer Fragmente abzuleiten.

Dehydration of the epimeric 23‐alcohols (I) in the (24R)‐stigmastane series using phosphorus oxychloride proceeds stereo‐ and regiospecifically to give the E‐ and Z‐stigmasta‐5,23‐dien‐3β‐ols (II) after deprotection.

Treatment of methylenestigmastenol (I) with trifluoroacetic acid results in opening of the cyclopropane ring, producing the olefins (II) ‐(IV).

The new sterols (I)‐(IV) are isolated from the title species.

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