A procedure has been developed for the assay of urinary porphyrins. Total porphyrins are extracted from acidified urine into n-butanol. The fluorescence of this solution under ultraviolet illumination gives a preliminary indication of abnormal levels of porphyrins. They are then separated and identified by thin-layer chromatography. Uroporphyrin and coproporphyrin can be qualitatively estimated...

Colour and pattern are key traits with important roles in camouflage, warning and attraction. Ideally, in order to begin to understand the evolution and ecology of colour in nature, it is important to identify and, where possible, fully characterise pigments using biochemical methods. The phylum Mollusca includes some of the most beautiful exemplars of biological pigmentation, with the vivid co...

I N CONNECTION with the designation of porphyria congenita ( Gunther) as p. erythropoietica 1,2 it was recognized that while many of the bone marrow normoblasts fluoresce and, in particular, exhibit strong nuclear fluorescence, many others, indistinguishable by ordinary morphologic criteria, did not exhibit porphyrin fluorescence. Many of the fluorescing forms exhibited heme containing nuclear ...

We studied the effect of polychlorinated biphenyls (PCBs) on hepatic porphyrin accumulation in female Sprague-Dawley rats by feeding them diets containing 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 2,2',4,4',5,5'-hexachlorobiphenyl (PCB 153), 2,3,3',4,4',5-hexachlorobiphenyl (PCB 156), 3,3',4,4',5-pentachlorobiphenyl (PCB 126), or combinations of the single PCB congeners with TCDD for 13 weeks...

The novel heme prosthetic group of Escherichia colt’ NADPH-sulfite reductase (EC 1.8.1.2) has been identified as an iron tetrahydroporphyrin of the isobacteriochlorin type (adjacent pyrrole rings reduced) with eight carboxylic acid side chains. The number of carboxyl groups was established by the following experiments. Esterification with 14CH30H resulted in incorporation of 7.4 moles of 14C pe...

Bacteria regulate the frequency and timing of DNA replication initiation by controlling the activity of the replication initiator protein DnaA. SirA is a recently discovered regulator of DnaA in Bacillus subtilis whose synthesis is turned on at the start of sporulation. Here, we demonstrate that SirA contacts DnaA at a patch of 3 residues located on the surface of domain I of the replication in...

a tradition reaching back to Talmudic times when rabbis were frequently acknowledged for their healing skills.' This trend developed during the medieval period in Europe, when Jews, excluded from practically all the learned professions, turned to medicine as a means of livelihood.2 As a result, the Jews have been esteemed for their medical skills and, in our own time, continue to occupy a disti...

The government-sponsored Foresight programme, begun four years ago with the aim of bringing together industrial companies with academic and research organisations to improve the competitiveness of the British economy, has now entered a second round of activity focusing on developing its range of tasks. In the area of sensing technology three themes are being taken up for collaboration by Sira d...

Porphyria cutanea tarda is associated with excess hepatic production of uroporphyrin. Oxidation of uroporphyrinogen to uroporphyrin was previously demonstrated to be specifically catalyzed by cytochrome P450 (CYP) 1A2. Here, we investigated the ability of human CYP1A2 to catalyze uroporphyrinogen oxidation (UROX). UROX activity in human liver microsomes was maximally only 10% of the activity in...