Paper electrophoresis of urinary porphyrins

High-performance liquid chromatography of porphyrins

Techniques for the analysis of porphyrins in the biomedical fields are reviewed. The emphasis is on high-performance liquid chromatography and its aspplications in: (1) the quantitative analysis of porphyrins in blood, urine and faeces; (2) qualitative porphyrin profiles in normal subjects and in the porphyrias; (3) assay of haem biosynthetic enzyme activities and (4) resolution of type isomers of porphyrins and porphyrinogens. Detection systems, quantitation methods, peak identification and sample preparation procedures are discussed.

Lactoperoxidase haem, an iron-porphyrin thiol

The haem prosthetic group of lactoperoxidase can be prepared from the enzyme in high yield by reductive cleavage with mercaptoethanol in 8 M-urea under mild conditions. The product yields porphyrins, after removal of iron, which show visible spectroscopic properties similar to protoporphyrin but are considerably more polar. In the presence of iodoacetamide, a different product is obtained by reductive cleavage. The proton n.m.r. and mass spectra of this compound indicate that the prosthetic group of the enzyme is the iron complex of 18-mercaptomethyl-2,7,12-trimethyl-3,8-divinylporphyrin-13,17-d ipropionic acid. It is proposed that the unusual strength of binding of the prosthetic group to the apoprotein is due to formation of a disulphide bond from a cysteine residue to the porphyrin thiol.

Case report of symptomatic porphyria cutanea tarda associated with histiocytic lymphoma

A fifth case is reported of symptomatic porphyria cutanea tarda (PCT) associated with lymphoma (of the histiocytic type) in a 45-year-old female. The PCT was documented in detail histologically and biochemically. The lymphoma was complicated by two paraneoplastic phenomena: inappropriate antidiuretic hormone secretion and peripheral neuropathy. It is possible that the PCT might also be a paraneoplastic phenomenon of the lymphoma. Search for an occult lymphoma may be of diagnostic and therapeutic value in patients presenting with PCT.

Diazinon and porphyria cutanea tarda

Cutaneous application of diazinon to rats over a period of 12 weeks gives rise to a condition biochemically indistinguishable from porphyria cutanea tarda. Faecal porphyrin levels are elevated with the appearance of isocoproporphyrin in the faeces. Oral administration of diazinon does not appear to cause any disturbance of porphyrin metabolism.

Erythropoietic uroporphyria of Gunther first presenting at 58 years with positive family studies

Erythropoietic uroporphyria of Gunther was seen in a 58-year-old man who presented with photosensitivity, haemolytic anaemia, and classical laboratory findings. Family studies showed five asymptomatic relatives with erythrocyte uroporphyrin concentrations in the probable latent heterozygote range.

Identification of a group of tetracarboxylate porphyrins, containing one acetate and three propionate -substituents, in faeces from patients with symptomatic cutaneous hepatic porphyria and from rats with porphyria due to hexachlorobenzene

1. Three tetracarboxylate porphyrins, apart from coproporphyrin, were isolated from the faeces of patients with symptomatic cutaneous hepatic porphyria and of rats with porphyria caused by hexachlorobenzene poisoning. The porphyrins were not present in the urine of the porphyric rats or in the faeces of control rats. 2. Two of the porphyrins were identified as tris-(2-carboxyethyl)-carboxymethyl ethyl trimethyl porphin (isocoproporphyrin) and tris-(2-carboxyethyl)-carboxymethyl trimethyl porphin (de-ethyliso-coproporphyrin). 3. The third porphyrin, previously reported to be an analogue of coproporphyrin in which one propionate group is replaced by an alpha- or beta-hydroxypropionate group, was shown to be tris-(2-carboxyethyl)-carboxymethyl-(1-hydroxyethyl)-trimethyl porphin (hydroxyisocoproporphyrin). 4. The order of beta-substituents around the porphin ring could not be determined for any of the compounds. 5. Evidence for the existence of a fourth porphyrin, tris-(2-carboxyethyl)-carboxymethyl trimethyl vinyl porphin (dehydroisocoproporphyrin), a postulated precursor of the others, is described. 6. It is suggested that dehydroisocoproporphyrinogen is produced by decarboxylation-dehydrogenation of one of the propionate groups of pentacarboxylate porphyrinogen III.