Tox&ron, 1975, Vol . 13, pp. 307-309. Perpamon Praa . Prlntad in Cmat Britain .
LETTER TO THE EDITOR NOMENCLATURE OF NATURALLY OCCURRING PEPTIDES (Accepted jor publication 11 March 197 Sttt : A group of workers (BOTE3 et al., 1974) concerned with the isolation and characterization of `toxic' polypeptides from venoms of the Proteroglyphae, have written to draw attention to the problem of nomenclature in this field. They have proposed a system which has some advantages in this particular area where, as they correctly point out, different groups of workers have used a number of wholly arbitrary methods of nomenclature. The system specifies the source, the immunochemical properties of the component, and is alleged to indicate the pharmacological properties (e.g. post- or pre-synaptic neurotoxin, cardiotoxin, etc.). In the case of the post-synaptic neurotoxins the size is also indicated since such polypeptides either contain 60-62 amino acid residues or 71-74. However, the proposals have some serious drawbacks. One relates to the difficulty of determining the precise pharmacological properties of individual polypeptides and another is the limited scope of the system when in fact the problem of nomenclature extends over the whole range of naturally occurring polypeptides, whether pharmacologically active or not. The case of bee venom, a rich source of polypeptides, some of which have been isolated and characterized, is illustrative of some of the difficulties . The first two polypeptide components isolated were called, by HAßi7tN1AN and RIIZ (196, Apamin and Melittin, both taken from the Latin name of the Common European honey bee, Apis mell{fica. Apamin, with 18 residues (SIIIPOI,tNt et al., 1967) has central nervous activity (ill-defined) while Melittin, with 26 residues (HnstattKnxx and Jt;lv~rzscx, 1967), is a natural detergent and therefore presumably a lytic agent. Habermann then went on to describe a peptide with 22 amino acid residues which he called `mast-cell degranulating peptide' on the basis of one of its biological effects (B1tßITHAUPT and Hns~nxx, 1968). The structure was determined by vorr Hnux (1969) . In our laboratory we isolated the same polypeptide independently and discovered that it was a very powerful anti-inflammatory agent (Bu,taxcHnM et al., 1973). (The system of nomenclature used in our laboratory gives numbers to fractions simply in the order of elution in column chromatographic purification steps. The antiinflammatory peptide is numbered 4.0 .1, this signifying much to us but little to anyone else.) It is not yet known whether the effect of peptide 4 .0.1 on mast cells is directly connected with its anti-inflammatory activity or not, but it is clearly not possible to specify its `pharmacological properties' in any simple manner. We have isolated yet another, 24 residue peptide from the same source called 2.8 .1 which has, as yet, no discernible pharmacological effects at all. The system proposed by Bozos et al. could not obviously be adapted to be applicable to components of bee venom. The principle introduced into our laboratory by one of us (R .A .S.) which lead to the isolation of Peptide 2.8 .1 from bee venom involves the separation of all the peptide components in a particular region of molecular weight, regardless of pharmacological activity.
Tox~coN t9~s vor.
13
307
308
BARBARA B. C. BANKS and RUDOLPH A. SHIPOL1Nt
By applying the same principle to the venom of a mamba, Dendroaspis viridis, we have isolated some thirteen peptides in the weight range corresponding to the curariform polypeptides from the venoms of other Proteroglyphae (Sfurotixc et al., 1973). Only three of these can be partly classified by the system proposed by Botes et al. These are the two long curare-like neurotoxins (4.7.3 and 4.9.3) and the short one (4.11 .3). These components have been found to be indistinguishable in their action in the frog nerve-sartorius preparation both with regard to their effects on the amplitudes of the end plate potentials and on the degree of reversibility (Bnxxs et al., 1974). However, the effects of these long and short neurotoxins on snail neurones are quite distinct from each other (Szczsrnxia,x, 1974). The long toxins block the normal hyperpolarization response of snail neurones to acetylcholine whereas the short toxin is without effect on either the hyperpolarization or depolarization responses. a-Bungaratoxin, which is a `long' toxin, does not behave in the same way as the `long' toxins from Dendroaspis viridis in the snail neurone preparation. If`pharmacological properties' are to be indicated in a systematic nomenclature, the particular test system must clearly be specified. Species variations in the response to pharmacologically active compounds are very familiar to pharmacologists and account must be taken of these. The remaining ten, homologous components from the venom of Dendroaspis viridis cannot be classified at all on the basis of pharmacological effects since none have so far been found. We feel that the simple definition of `pharmacological properties' proposed by Botes et al. i s inappropriate, even for the closely related polypeptides from venoms of the Proteroglyphae. The immunological classification proposed by BoQUSr et al. (1973), which now extends to five recognizable groups, may be of more value as illustrated by the grouping of a component (Fraction 5) of the venom of Naja melanoleuca with the `long' toxins on the basis of its immunological behaviour, whereas an early amino acid analysis had indicated that it might be a short toxin. Total sequence determination (SHIPOLINI et al., 1974) confirmed the immunological classification . The letter in Toxicon is headed `Nomenclature of snake venom toxins', whereas the system proposed is only applicable to components isolated from the venoms of a particular sub-order, the Proteroglyphae, which includes cobras, mambas and sea snakes . In Europe, at any rate, envenomation by vipers is far more common and here the situation is more obscure than is the case with the elapids and hydrophids . Clinicians well recognize that the symptoms of viperid envenomation are very variable while biochemically the venoms have as yet not been well characterized . The mode of action of the most toxic components is unknown but there is some indication that they may be associated with phospholipase A activity, an effect noted by Habermann (private communication) for the component of the dissociated form of crotoxin, the major toxin from the venom of the crotalid, Crotales terrificus territices. A system of nomenclature for snake venom toxins must surely accommodate these larger molecules even before their mode of action is established? Beyond the field of venom components whether the venom be of wasp, bee, spider, scorpion or snake, lies an important class of highly active, smaller peptides isolated from various frogs' skins (BERTACCINI, 1971). The names ofthese, Bombesin, Caerulein, Eledoisin, Phyllomedusin, etc., are derived from the Latin name of the particular species from which the molecules were isolated . All have complex pharmacological effects. They are not entirely homologous and vary in size from deca. to tetradeca., while some activities ca.n be found associated with fragments of the naturally occurring parent compound. Clearly there is a severe problem relating to the nomenclature of naturally occurring TOXICON I97S Vol. l3
Nomenclature of Naturally Occuaing Peptides
309
peptides and, as more are isolated, the problem increases. An ideal system would presumably indicate source, structure and activity, but unfortunately it is the last of these that is the hardest to specify. In the case of enzymes, the classification is based on a well-defined chemical reaction-except notably in the case of the proteolytic enzymes-while the primary structures of the enzymes are irrelevant to the system. In the case of polypeptides, the primary structures are far more readily specified but the biological effects are very much harder to establish . Perhaps the time is near for an International Commission to investigate this problem. On such a commission there would have to be representatives from several disciplines, including Zoologists to specify the source, Biochemists and Chemists to specify the struo turcs and, most importantly, Pharmacologists to tackle the most difficult problem, that of activity . University College London, Gower Street, London WC1E 6BT.
Bnnsnxn E. C. Baxtcs Department of Physiology Runotrx A. SI-IIPOLIIVt Department of Chemistry REFERENCES
Bxxgs, B. E. C., Mut:nt, R. and Stm'oLnvt, R. A. (1974) The primary sequecr and neuromuscular effects of three neurotoxic polypeptides from the venom of Dendroaspis viridts. Eur. J. Biochem. 45, 457. BBRTACCIM, G. (1971) Active polypeptides in amphibian skin . Naunyn-Schmiedebergs Arch. exp. Path . Pharmak. 269, 139. BIII.INGHAM, M. E. J., Motu av, J., I~xsox, J. M., St~or nat, R. A. and Vatexox, C. A. (1973) An antiinflammatory peptide from bee venom. Nature, Lond. 245, 163. BoQusr, P., Pout~ux, G., Dua~xev, C., Iznttn, Y. and RotvssExnv, A. M. (1973) An attempt to classify the toxic proteins of Elapidae and Hydrophicdae venoms. Toxicon 11, 333. Bow, D. P., Cnxrssox, F. H. H., JoussxT, F. J., Loves, A. L, STttYnoM, A. J. C., S~rxvnoM, D. l. and Vutot:rt, C. C. (1974) Nomenclature of snake venom toxins . Tozicon 12, 99. Bttxtzxeurr, H. and Haslaut~x, E. (1968) Mastzelldegranulierendes peptid (MCD-peptid) aus Bienengift : Isolierung biochemische und pharmakologische Eigenschaften . Arch . exp. Path . Pharmac. 261, 252. H,~sP.tuuxx, E. and Jextzscx, J. (1967) Sequenzanalyse der Melittins aus den tryptischen und peptischen Spaltstûcken . Hoppe-Seyler's Z. physiol. Chem . 348, 37 . HnHmrf .~.nx, E. and Rstz, K. G. (1965) ZurBiochimie der Bienengift peptide Melittin und Apamin. Biochim. Z. 343, 192. vox Hnvx, P. (1969) Mastzellen-degranulierendes peptid aus Bienengift, Aminosaures sequens. HoppeSeylers Z. physlol. Chem. 350, 536. StvPOt txt, R. A., BAILEY, G. S. and B~xxs, B. E. C. (1974) The separation of a neurotoxin from the venom of NaJa »ulanoleuca and the primary sequence determination. Eur. J. Biochem. 42, 203. SEnrot uvl, R. A., BAILEY, G. S., Enwaxnsox, J. A. and BAxxs, B. E. C. (1973) Separation and characterisation of polypcptides from the venom of Dendroaspis viridis. Eur. J. Biochem. 40, 337. SHIPOLIHI, R. A., BRADHURY, A. F., CALLEWAERT, G. L. and VEarrox, C. A. (1967) The structure of apamin . Chem. Cormnun. 679. Szcz~Arrux, A. C. (1974) Effect of a-bungarotoxin and Dendroaspis neurotoxins on acetylcholine responses in snail neurones. J. Physiol. 241, 55 .
TOXICON 1975 Vot. 13
LETTER TO THE EDITOR NOMENCLATURE OF NATURALLY OCCURRING PEPTIDES (Accepted jor publication 11 March 197 Sttt : A group of workers (BOTE3 et al., 1974) concerned with the isolation and characterization of `toxic' polypeptides from venoms of the Proteroglyphae, have written to draw attention to the problem of nomenclature in this field. They have proposed a system which has some advantages in this particular area where, as they correctly point out, different groups of workers have used a number of wholly arbitrary methods of nomenclature. The system specifies the source, the immunochemical properties of the component, and is alleged to indicate the pharmacological properties (e.g. post- or pre-synaptic neurotoxin, cardiotoxin, etc.). In the case of the post-synaptic neurotoxins the size is also indicated since such polypeptides either contain 60-62 amino acid residues or 71-74. However, the proposals have some serious drawbacks. One relates to the difficulty of determining the precise pharmacological properties of individual polypeptides and another is the limited scope of the system when in fact the problem of nomenclature extends over the whole range of naturally occurring polypeptides, whether pharmacologically active or not. The case of bee venom, a rich source of polypeptides, some of which have been isolated and characterized, is illustrative of some of the difficulties . The first two polypeptide components isolated were called, by HAßi7tN1AN and RIIZ (196, Apamin and Melittin, both taken from the Latin name of the Common European honey bee, Apis mell{fica. Apamin, with 18 residues (SIIIPOI,tNt et al., 1967) has central nervous activity (ill-defined) while Melittin, with 26 residues (HnstattKnxx and Jt;lv~rzscx, 1967), is a natural detergent and therefore presumably a lytic agent. Habermann then went on to describe a peptide with 22 amino acid residues which he called `mast-cell degranulating peptide' on the basis of one of its biological effects (B1tßITHAUPT and Hns~nxx, 1968). The structure was determined by vorr Hnux (1969) . In our laboratory we isolated the same polypeptide independently and discovered that it was a very powerful anti-inflammatory agent (Bu,taxcHnM et al., 1973). (The system of nomenclature used in our laboratory gives numbers to fractions simply in the order of elution in column chromatographic purification steps. The antiinflammatory peptide is numbered 4.0 .1, this signifying much to us but little to anyone else.) It is not yet known whether the effect of peptide 4 .0.1 on mast cells is directly connected with its anti-inflammatory activity or not, but it is clearly not possible to specify its `pharmacological properties' in any simple manner. We have isolated yet another, 24 residue peptide from the same source called 2.8 .1 which has, as yet, no discernible pharmacological effects at all. The system proposed by Bozos et al. could not obviously be adapted to be applicable to components of bee venom. The principle introduced into our laboratory by one of us (R .A .S.) which lead to the isolation of Peptide 2.8 .1 from bee venom involves the separation of all the peptide components in a particular region of molecular weight, regardless of pharmacological activity.
Tox~coN t9~s vor.
13
307
308
BARBARA B. C. BANKS and RUDOLPH A. SHIPOL1Nt
By applying the same principle to the venom of a mamba, Dendroaspis viridis, we have isolated some thirteen peptides in the weight range corresponding to the curariform polypeptides from the venoms of other Proteroglyphae (Sfurotixc et al., 1973). Only three of these can be partly classified by the system proposed by Botes et al. These are the two long curare-like neurotoxins (4.7.3 and 4.9.3) and the short one (4.11 .3). These components have been found to be indistinguishable in their action in the frog nerve-sartorius preparation both with regard to their effects on the amplitudes of the end plate potentials and on the degree of reversibility (Bnxxs et al., 1974). However, the effects of these long and short neurotoxins on snail neurones are quite distinct from each other (Szczsrnxia,x, 1974). The long toxins block the normal hyperpolarization response of snail neurones to acetylcholine whereas the short toxin is without effect on either the hyperpolarization or depolarization responses. a-Bungaratoxin, which is a `long' toxin, does not behave in the same way as the `long' toxins from Dendroaspis viridis in the snail neurone preparation. If`pharmacological properties' are to be indicated in a systematic nomenclature, the particular test system must clearly be specified. Species variations in the response to pharmacologically active compounds are very familiar to pharmacologists and account must be taken of these. The remaining ten, homologous components from the venom of Dendroaspis viridis cannot be classified at all on the basis of pharmacological effects since none have so far been found. We feel that the simple definition of `pharmacological properties' proposed by Botes et al. i s inappropriate, even for the closely related polypeptides from venoms of the Proteroglyphae. The immunological classification proposed by BoQUSr et al. (1973), which now extends to five recognizable groups, may be of more value as illustrated by the grouping of a component (Fraction 5) of the venom of Naja melanoleuca with the `long' toxins on the basis of its immunological behaviour, whereas an early amino acid analysis had indicated that it might be a short toxin. Total sequence determination (SHIPOLINI et al., 1974) confirmed the immunological classification . The letter in Toxicon is headed `Nomenclature of snake venom toxins', whereas the system proposed is only applicable to components isolated from the venoms of a particular sub-order, the Proteroglyphae, which includes cobras, mambas and sea snakes . In Europe, at any rate, envenomation by vipers is far more common and here the situation is more obscure than is the case with the elapids and hydrophids . Clinicians well recognize that the symptoms of viperid envenomation are very variable while biochemically the venoms have as yet not been well characterized . The mode of action of the most toxic components is unknown but there is some indication that they may be associated with phospholipase A activity, an effect noted by Habermann (private communication) for the component of the dissociated form of crotoxin, the major toxin from the venom of the crotalid, Crotales terrificus territices. A system of nomenclature for snake venom toxins must surely accommodate these larger molecules even before their mode of action is established? Beyond the field of venom components whether the venom be of wasp, bee, spider, scorpion or snake, lies an important class of highly active, smaller peptides isolated from various frogs' skins (BERTACCINI, 1971). The names ofthese, Bombesin, Caerulein, Eledoisin, Phyllomedusin, etc., are derived from the Latin name of the particular species from which the molecules were isolated . All have complex pharmacological effects. They are not entirely homologous and vary in size from deca. to tetradeca., while some activities ca.n be found associated with fragments of the naturally occurring parent compound. Clearly there is a severe problem relating to the nomenclature of naturally occurring TOXICON I97S Vol. l3
Nomenclature of Naturally Occuaing Peptides
309
peptides and, as more are isolated, the problem increases. An ideal system would presumably indicate source, structure and activity, but unfortunately it is the last of these that is the hardest to specify. In the case of enzymes, the classification is based on a well-defined chemical reaction-except notably in the case of the proteolytic enzymes-while the primary structures of the enzymes are irrelevant to the system. In the case of polypeptides, the primary structures are far more readily specified but the biological effects are very much harder to establish . Perhaps the time is near for an International Commission to investigate this problem. On such a commission there would have to be representatives from several disciplines, including Zoologists to specify the source, Biochemists and Chemists to specify the struo turcs and, most importantly, Pharmacologists to tackle the most difficult problem, that of activity . University College London, Gower Street, London WC1E 6BT.
Bnnsnxn E. C. Baxtcs Department of Physiology Runotrx A. SI-IIPOLIIVt Department of Chemistry REFERENCES
Bxxgs, B. E. C., Mut:nt, R. and Stm'oLnvt, R. A. (1974) The primary sequecr and neuromuscular effects of three neurotoxic polypeptides from the venom of Dendroaspis viridts. Eur. J. Biochem. 45, 457. BBRTACCIM, G. (1971) Active polypeptides in amphibian skin . Naunyn-Schmiedebergs Arch. exp. Path . Pharmak. 269, 139. BIII.INGHAM, M. E. J., Motu av, J., I~xsox, J. M., St~or nat, R. A. and Vatexox, C. A. (1973) An antiinflammatory peptide from bee venom. Nature, Lond. 245, 163. BoQusr, P., Pout~ux, G., Dua~xev, C., Iznttn, Y. and RotvssExnv, A. M. (1973) An attempt to classify the toxic proteins of Elapidae and Hydrophicdae venoms. Toxicon 11, 333. Bow, D. P., Cnxrssox, F. H. H., JoussxT, F. J., Loves, A. L, STttYnoM, A. J. C., S~rxvnoM, D. l. and Vutot:rt, C. C. (1974) Nomenclature of snake venom toxins . Tozicon 12, 99. Bttxtzxeurr, H. and Haslaut~x, E. (1968) Mastzelldegranulierendes peptid (MCD-peptid) aus Bienengift : Isolierung biochemische und pharmakologische Eigenschaften . Arch . exp. Path . Pharmac. 261, 252. H,~sP.tuuxx, E. and Jextzscx, J. (1967) Sequenzanalyse der Melittins aus den tryptischen und peptischen Spaltstûcken . Hoppe-Seyler's Z. physiol. Chem . 348, 37 . HnHmrf .~.nx, E. and Rstz, K. G. (1965) ZurBiochimie der Bienengift peptide Melittin und Apamin. Biochim. Z. 343, 192. vox Hnvx, P. (1969) Mastzellen-degranulierendes peptid aus Bienengift, Aminosaures sequens. HoppeSeylers Z. physlol. Chem. 350, 536. StvPOt txt, R. A., BAILEY, G. S. and B~xxs, B. E. C. (1974) The separation of a neurotoxin from the venom of NaJa »ulanoleuca and the primary sequence determination. Eur. J. Biochem. 42, 203. SEnrot uvl, R. A., BAILEY, G. S., Enwaxnsox, J. A. and BAxxs, B. E. C. (1973) Separation and characterisation of polypcptides from the venom of Dendroaspis viridis. Eur. J. Biochem. 40, 337. SHIPOLIHI, R. A., BRADHURY, A. F., CALLEWAERT, G. L. and VEarrox, C. A. (1967) The structure of apamin . Chem. Cormnun. 679. Szcz~Arrux, A. C. (1974) Effect of a-bungarotoxin and Dendroaspis neurotoxins on acetylcholine responses in snail neurones. J. Physiol. 241, 55 .
TOXICON 1975 Vot. 13
