Coproporphyrin-III

Isolated significant increases in ALA may indicate a lead intoxication, especially if combined with an increase in coproporphyrin III isomer. Alternatively, this pat-... 

All acute porphyrias show similar urinary porphyrin patterns with predominant elevation of uroporphyrin and coproporphyrin III isomer in addition, hepta-, hexa-, and especially pentacarboxyporphyrins are increased (see Fig. 7.3.3). 

Table 7.3.3 Example mean reference values for uroporphyrin, coproporphyrin I, and coproporphyrin III (these can only be interpreted as a guidance) collected by means of high-performance liquid chromatography (HPLC). The intermediary porphyrins were below the detection limit...

Age years Uroporphyrin gmol/mol creatinine Coproporphyrin I pmol/mol creatinine Coproporphyrin III pmol/mol creatinine... 

Fecal porphyrins are determined to differentiate between the three acute porphyrias, AIP, PV, and HC (Table 7.3.1). Symptomatic PV shows abundant fecal coproporphyrins, whereby the III isomer is always dominant and protoporphyrin is elevated. In symptomatic HC, only fecal coproporphyrins with dominance of the III isomers are increased. Fecal porphyrins are usually normal in AIP. They may be moderately elevated in acute porphyric attacks in AIP, but coproporphyrin I is then higher than coproporphyrin III isomer [11]. 

Each laboratory should establish its own reference values. Those given here can only be interpreted as a guide. To our knowledge, the age dependence of fecal porphyrin excretion has not been studied. The following values for coproporphyrin I, coproporphyrin III, and protoporphyrin represent the meant two standard deviations ( 2SD) and were assessed in samples from adult volunteers <20, < 12, and < 80 nmol/g dry weight, respectively. 

Each laboratory should establish its own reference values. Those given here can thus only be interpreted as a guide. Porphyrins in plasma are rarely detectable in healthy individuals. Patients on chronic dialysis but without signs of PCT may show some measurable values, which are given here as reference values (nmol/1, mean 2SD) uroporphyrin <24.3 heptacarboxyporphpyrin <2.7 hexacarboxyporphyrin <1 pentacarboxyporphyrin < 1 coproporphyrin I < 1 coproporphyrin III < 1. 

Methods using condensations of two dipyrrolic units suffer from inherent symmetry restrictions, though these are of course less serious than those involved in the use of monopyrrole tetramerization. Thus the routes through dipyrroles are limited to synthesis of porphyrins which are centrosymmetrically substituted (by way of self-condensation of a suitably activated dipyrrole), or to porphyrins which possess subunit symmetry in one or both halves of the molecule. It is very fortunate that this latter restriction is not serious for the synthesis of porphyrins from natural materials because rings c and d of uroporphyrin-III, coproporphyrin-III and protoporphyrin-IX (Table 1), for example, are symmetrically substituted about the C-15 atom. 

Uroporphyrins I and III are both excreted in small amounts in the urine. Another excretion product is coproporphyrin III, in which all of the carboxymethyl side chains have been decarboxylated to methyl groups. The feathers of the tropical touraco are colored with copper(II) complex of coproporphyrin III and this... 

B) Coproporphyrin III. Note that a different tautomeric form is pictured in B than in A. Tautomerism of this kind occurs within all of the porphyrins. (C) Protoheme, the Fe2+ complex of protoprophyrin IX, present in hemoglobin, cytochromes b, and other proteins. 

Copper-sulfide cluster 884s Coproporphyrin III 843,845s Comified cell envelope 439 Corrin in transmethylation 592 Corrin ring 867, 868 Corrinoid-dependent synthesis of acetyl-CoA 876, 877 Cosmarium 22 COSY-NOESY diagram 143 Cotransport (symport) process 411,416,417 Coulomb 283... 

Lead exposure mcreases urinary ALA and coproporphyrin-III excretion and causes accumulation of 2n-protoporphyrin in erythrocytes. The definitive test for lead toxicity is measurement of blood lead, but occasionally lead exposure is responsible for porphyria-like symptoms and may be an unexpected finding when investigating patients for suspected porphyria. ... 

In the Dubin-Johnson syndrome there is increased urinary excretion of coproporphyrin-I and a reduced excretion of coproporphyrin-III. In Rotor s syndrome, urinary excretion of coproporphyrin-I is increased with normal coproporphyrin-IIl excretion,and in Gilbert s disease there is increased urinary excretion of both isomers. 

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