284 W. W. Wainio 



group, the nature of which was not then known. Lemberg (1953) chose to 

 isolate the porphyrin and identified three characteristic side chains. These 

 were a rhodofying group which is almost certainly a formyl group, a second 

 rhodofying group containing an ethylenic double bond, and a large alkyl or 

 fatty-acid nonesterified side chain. 



The structure of haem a has also interested Warburg for many years. 

 Warburg, Gewitz and Volker (1955) fused haemin a, obtained from beef 

 heart, with resorcinol and obtained a cytodeuteroporphyrin which differed 

 from deuteroporphyrin in its melting point and in its reaction with bromine. 

 Cytodeuteroporphyrin took up three atoms of bromine which suggested 

 that there were three free positions. The problem has been studied further by 

 Marks, Dougall, Bullock and McDonald (1959), who concluded that cyto- 

 deuteroporphyrin is deuteroporphyrin with hydrogen for methyl in the 

 8-position. Thus cytodeuteroporphyrin, a derivative of porphyrin a, would 

 have three methyl groups, 1, 3 and 5, two propionic acid side chains, 6 and 

 7, and three free positions, i.e. hydrogens, 2, 4 and 8. 



In a very recent report, which is available only in abstract form, Morrison 

 and Stotz (1959) state that haemin a has a molecular weight of 880. According 

 to them it is a dicarboxylic acid having two propionic acid side chains, three 

 methyl groups, a formyl group, a ketone aliphatic side chain containing 14 

 carbon atoms, and a vinyl group attached to the porphyrin nucleus. 



The foremost question with regard to the haem is whether there are two 

 haems a or one. Morrison and Stotz (1955) found that they could separate 

 two haemins of the a type on a silicic acid column from the purified cyto- 

 chrome c oxidase preparation of Smith and Stotz (1954). The two haemins 

 were at first labelled a^ and a^, a nomenclature now withdrawn. Their 

 pyridine haemochromes had identical spectra. They subsequently found 

 (Morrison, Connelly and Stotz, 1958) that there was cross-contamination of 

 the two components on the column. With the aid of a new paper chromato- 

 graphic technique they obtained the pure compounds. The reduced pyridine 

 haemochrome of haemin a^ has its a-maximum at 582 m/t and has a small 

 /?-peak at 533 vafx. The corresponding compound of haemin a^, has a maxi- 

 mum at 587 m/i and no /S-peak. They identified haemin a^ with crypto- 

 haemin a of Lemberg (1953), but did not agree with the suggestion that 

 cryptohaemin a and presumably therefore haemin a-^ may be an artifact of the 

 preparative procedure. 



In the isolations performed by Lemberg (1953), porphyrin a was always 

 accompanied by another porphyrin whose haemin had maxima at 533 mj-i 

 and 582 m/^ in pyridine-dithionite. This component was called cryptopor- 

 phyrin a. Its yield from wet heart muscle was about 0-7 mg/kg which is to be 

 compared with the 16-18 mg/kg of porphyrin a that was obtained. On this 

 basis Lemberg concluded that even if cryptoporphyrin a is derived from 

 haemin a and is not an artifact, it is present in too small a concentration to 



