Franck nomenclature

Throughout this book an effort has been made to use both the original authors trivial names as well as designations based on a Franck-type approach. Since the rationale for using this latter systematic nomenclature is to allow for easy inter-comparisons between classes of molecules, a formal definition is appropriate here. For a given macrocycle, the number of pyrrole or pyrrole-like substituents is first determined and the system designated as being a porphyrin (four subunits), pentaphyrin (five subunits), hexaphyrin (six subunits), etc., as warranted. This compound name is then preeeded by a number (in brackets) that indieates the... 

Analysis of the products indicated that these new macrocycles consisted of six pyrrolic subunits linked in a (1.1.1.1.1.1) fashion by six methine subunits. As such, they may be referred to as being [26]hexaphyrins-(l.l.l.l.l.l) in the Franck-type nomenclature used in this book. Here, the key macrocycle name, hexaphyrin, came from Gossauer. Indeed, because this investigator viewed products 7.9-7.12 as being the next higher porphyrin homolog in the porphyrin-pentaphyrin series coined the term hexaphyrin for this class of macrocycles. 

The nomenclature is not quite lixed, but that given here seems to be gradually becoming established. As a matter of history, it ma,y bo noted that the distinction between heteropolar and homopolar binding was first drawn by Abcgg the separation into ionic and atomic binding, with the criterion of the dissociation products, was introduced by Franck. 

Porphyrinoids (porphyrin analogues, porphyrin homologues and porphyrin vinylogues [31]), like porphyrins, are of interest as sensitizers in photodynamic tumour therapy [32]. Some of these systems, e.g. 41 - 43 have been synthesized (Franck, Vogel 1990) [33]. Their nomenclature takes into account the cyclic conjugation of the annulene perimeter and the number of methine groups between the four pyrrole units, e.g. porphyrin 1 is described as [18]porphyrin(l.l.l.l) porphycin 43, which is isomeric with porphyrin, is known as [18]porphyrin(2.0.2.0). 

Two main types in soybean are now known (Table II). The classic Theorell enzyme is LOX-1. Some confusion exists in the nomenclature, because Verhue and Francke (1972) called this form the acid enzyme (active on free fatty acids only) and Grosch et al. (1977) referred to it as the alkaline enzyme (the pH optimum is 9). The second type, LOX-2, is optimally active at pH 6.5 this is the ester enzyme of Verhue and Francke (1972), the neutral enzyme of Grosch ef al. (1977), and the b enzyme of Yamo-moto et al. (1970). The type-1 and type-2 nomenclature is now used by most workers and should be retained to avoid ambiguities. Both types are further separated into isoenzymic forms Grosch et al. (1977) refer to LOX-1,1 and LOX-1,2 isoenzymes from type 1, and LOX-2,1 and LOX-2,2 isoenzymes from type 2. Christopher et al. (1972) and Weber et al. (1974) describe a type-3 enzyme, but results (Grosch et al., 1977) indicate that this may be a mixture of isoenzymes. The major differences between types 1 and 2 are summarized in Table II. 

The structure determination revealed that all the known ergochromes are dimers of the monoxanthones A-F, linked at C(2). This made possible a simple, systematic nomenclature, which characterizes the ergochromes by an additional specification AA, AB, or BB, according to the types of their monomeric units A, B, etc. (Franck et ai, 1964, 1966). These systematic names are shown in Table I with their frequently used original names, the corresponding structures, and the occurrence of the ergochromes. 

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