Showing papers on "Protoporphyrin IX published in 1975"

Heme biosynthesis in bacterium-protozoon symbioses: enzymic defects in host hemoflagellates and complemental role of their intracellular symbiotes.

Abstract: Heme biosynthetic activity in the symbiotic association involving crithidial flagellates and intracellular bacteroids was studied by enzymic, nutritional, and isotope incorporation experiments. Component organisms and their complexes in this association were analyzed separately to determine the underlying cause of the hemin requirement of hemoflagellates and the role of symbiotes in sparing this requirement of two crithidial species. Nutritional study of symbiote-free flagellates showed that their growth requires at least 0.1 mug/ml of hemin, which can be substituted by protoporphyrin IX, but not by the porphyrin precursors, delta-amino-levulinic acid or porphobilinogen. These flagellates, in the presence of protoporphyrin IX, incorporated 59Fe into heme, indicating that they possess ferrochelatase (EC 4.99.1.1), the terminal enzyme in the heme biosynthetic pathway, which catalyzes the insertion of iron into protoporphyrin IX. In symbiote-containing flagellates serially cultured in a defined medium free of tetrapyrrole compounds, heme and porphyrins can be detected by a fluorophotometric method, indicative of heme biosynthesis. Study of [14C]glycine incorporation into heme showed that the rate is much higher in symbiote-containing flagellates than in those without symbiotes. Microassay of uroporphyrinogen I synthase [EC 4.3.1.8; porphobilinogen ammonia-lyase (polymerizing)] revealed that the specific activity is high in symbiote-containing flagellates and higher still in isolated symbiotes, but essentially negligible in symbiote-free organisms. It is concluded that the bacterial symbiotes augment a very limited heme biosynthetic capacity of host flagellates by supplying uroporphyrinogen I synthase and perhaps other enzymes preceding ferrochelatase in the heme biosynthetic chain.

Stereochemistry of biosynthesis of the vinyl groups of protoporphyrin-IX: a short synthesis of porphobilinogen

Abstract: Porphobilinogen (1), [2H]-labelled in the propionic residue, is synthesised by a short route and is used to establish that both vinyl groups of protoporphyrin-IX are biosynthesised by overall antiperiplanar elimination of a proton and carbon dioxide.

A Possible Role of Copper in the Regulation of Heme Biosynthesis Through Ferrochelatase

Abstract: Drugs and heavy metals may alter the synthesis of hemo-proteins by either inducing or inhibiting various enzymes in the heme biosynthetic pathway (Fig. 1) (Tephly et al., 1971; Tephly et al., 1973). Porphyrogenic drugs and inducers of the hepatic hemo-protein, cytochrome P-450, such as phenobarbital, induce hepatic δ-aminolevulinic acid synthetase (ALAS), the initial and proposed rate-limiting enzyme of this pathway (Granick and Urata, 1963; Baron and Tephly, 1969; Tephly et al., 1973). Ferrochelatase (heme synthetase, protoheme ferro-lyase, EC 4.99.1.1), the terminal enzyme in the heme pathway, is located on the inner mitochondrial membrane (Jones and Jones, 1968; McKay et al., 1969) and catalyzes the formation of heme from protoporphyrin IX and ferrous iron (Labbe and Hubbard, 1960). This enzyme, like ALAS, is inducible (Hasegawa et al., 1970; Tephly et al., 1971), and may be subject to product inhibition by heme (Jones and Jones, 1970). Heme which is formed through ferrochelatase is then available for synthesis of cytochrome P-450 and other hemoproteins. Tephly and co-workers (Tephly and Hibbeln, 1971; Tephly et al., 1972) have reported that cobalt treatment produces a substantial decrease in the level of hepatic cytochrome P-450.

Mutant of the yeast Saccharomycopsis lipolytica that accumulates and excretes protorphyrin IX.

Abstract: The red, water-insoluble pigment excreted by a mutant strain of the yeast Saccharomycopsis lipolytica is show to be protoporphyrin IX. In genetic crosses the red phenotype has the properties characteristic of a defect in a single, recessive nuclear gene. The yield and ease of harvest of protoporphyrin IX from the yeast mutant indicate that this strain or its derivatives may be a valuable source of this substance.

Assignment of the n.m.r. spectrum of iron(III) protoporphyrin IX dicyanide using paramagnetic shift and broadening probes

Abstract: Specific assignments of the paramagnetically shifted porphyrin ring proton resonances in the n.m.r. spectrum of iron(III)protoporphyrin IX dicyanide have been made by consideration of the perturbations induced in the spectrum by paramagnetic shift and relaxation probes.