Alcohol-water as a novel medium for beta-hematin preparation.

It is shown that alcohol-water mixtures (e.g., 43 wt% ethanol) provide a suitable medium for the efficient production in high yield of beta-hematin from ferriprotoporphyrin IX (FP), as measured by infrared spectroscopy.

On the preparation of beta-haematin.

Synthetic beta-haematin is considered to be identical, or at least very similar to, purified malaria pigment. Methods for its preparation use ferriprotoporphyrin IX at acid pH in the presence of acetic acid at different concentrations and degrees of ionization, elevated temperatures and long reaction times. Here we show that certain widely used reaction conditions, involving very high concentrations of acetic acid/acetate mixtures, do not produce substantial amounts of polymeric beta-haematin on immediate isolation of the reaction products, but only during prolonged drying of the products at 37 degrees C after washing with water.

Investigations of B- and beta-hematin.

The preparation from ferriprotoporphyrin IX (FP) in aqueous acid medium of the related pigments beta- and B-hematin [see G. Blauer and M. Akkawi, Biochem.

B-hematin.

Very rapid production in vitro of a particular type of hematin (B-hematin) with high yield at physiological pH and temperature is presently reported, using a simple chemical system including an organic acid in the absence of any enzyme. B-hematin is characterized by infrared spectra and solubility properties. The antimalarial drug chloroquine practically prevents formation of this hematin under the conditions used.

Circular dichroism of ferriprotoporphyrin IX-morphine complexes in aqueous solution.

Complexes of ferriprotoporphyrin IX (FP) with (-)-morphine exhibit large optical activity in aqueous solution. Several CD bands of different signs were recorded under different conditions in the wavelength range of 300 to 450 nm. The largest CD band, centered at about 364 nm, showed molar ellipticities of about -5 x 10(5) deg.

Further evidence for the interaction of the antimalarial drug amodiaquine with ferriprotoporphyrin IX.

Evidence for complex formation of the antimalarial drug amodiaquine (AD) with ferriprotoporphyrin IX (FP) in aqueous medium is presented, in addition to previous preliminary data. A mole ratio of one between the complex components is determined for the insoluble complex at pH 6.7-6.

Optical activity of hemoproteins in the Soret region. Circular dichroism of the heme undecapeptide of cytochrome c in aqueous solution.

Different possible mechanism for generation of optical activity of hemoproteins in the Soret region are reconsidered. The heme undecapeptide of cytochrome c does not contain aromatic amino acid residues, so its considerable optical activity cannot be due to coupling of heme pi pi * transitions with those of aromatic residues. CD data for the heme undecapeptide and for ferrimyoglobin and some of their complexes with small molecules are presented and critically compared.

Interaction of ferriprotoporphyrin IX with the antimalarials amodiaquine and halofantrine.

Light-absorption spectra in the range of 350 to 650 nm of ferriprotoporphyrin IX (ferriheme), both in the presence and absence of either amodiaquine or halofantrine, have been compared in aqueous solution (pH 7.4) at room temperature. In the presence of the drugs, a distinct absorption maximum in the region of 600 to 610 nm, a shoulder near 490 to 500 nm, a maximum around 393 nm and a shoulder near 370 nm have been recorded.

Complexes of bilirubin with proteins.

Complexes of bilirubin with chymotrypsin, lysozyme and apomyoglobin in neutral aqueous solution are characterized by circular dichroism spectra in the visible region. These are analogous to previously investigated bilirubin-serum albumin complexes. Ferriprotoporphyrin IX displaces bilirubin from its apomyoglobin complex.

Optical properties of complexes of antimalarial drugs with ferriprotoporphyrin IX in aqueous medium. II. The system ferriprotoporphyrin IX-quinidine.

Light absorption and circular dichroism (CD) were recorded at 26 to 27 degrees C in dilute aqueous solutions (10(-4) M) of ferriprotoporphyrin IX (FP) in the presence of (+)-quinidine. In contrast to the appearance of relatively small and positive CD bands between pH 7 and 10, two bands of opposite sign, having unusually large molar ellipticities of the order of 10(6) deg X cm2 X dmol-1 FP were observed in the Soret region near 400 nm at pH 11.0-11.

Optical properties of complexes of antimalarial drugs with ferriprotoporphyrin IX in aqueous medium. I. The system ferriprotoporphyrin IX-quinine.

Circular dichroism (CD) and light-absorption spectra of the system ferriprotoporphyrin IX-(-)-quinine as measured at 26 to 27 degrees C in dilute aqueous solutions of both pH 7.4 and 11.5 are reported.

Optical properties and structure of tetrapyrroles. A report of a symposium held at the University of Konstanz, FRG, August 12-17, 1984.

Many basic life processes such as oxygen transport, electron transport, photosynthesis and plant development, are mediated by tetrapyrroles. It has long been recognized that optical and other physicochemical properties of tetrapyrroles are highly important not only for characterization of the various relevant systems but also to provide a key role in the understanding of their structural and functional aspects. The symposium described below was devoted mainly to recent advances in the optical and molecular properties of biologically important systems, involving both cyclic and open-chain tetrapyrroles.

Relative affinities of bilirubin for serum albumins from different species.

Relative equilibrium constants ("affinity ratios") of complexes of bilirubin with a molar excess of charcoal-treated serum albumins from different species (human, bovine, rabbit and chicken) in aqueous solution, were estimated by circular dichroism measurements in the visible region at 26-27 degrees C, pH 7.4, and in the presence of 0.1 M NaCl.