11S and 7S globulins of coconut (Cocos nucifera L.): purification and characterization

Total globulins extracted with 0.4 M NaCl in buffer from coconut endosperm separated into two peaks on gel filtration: peak I corresponding to 11S globulin or cocosin and peak II to 7S globulin with native molecular weights of 326 000 and 156 000, respectively. The percent composition of total globulins was estimated to be 11S, 86% and 7S, 14%. On SDS-PAGE, cocosin resolved into two closely migrating bands at approximately 34 000 (acidic polypeptide) and another set of 2 bands at 24 000 (basic polypeptide). Each set consisted of one darkly stained band and one lightly stained band. The 7S globulin consisted of three bands of 16 000, 22 000, and 24 000. Three isoforms of cocosin were identified after anion exchange chromatography. Cocosin, but not the 7S, was found to have disulfide bonds. Using periodic acid-Schiff's reagent, all of the bands of cocosin on SDS-PAGE were positive for carbohydrate. However, when con A-peroxidase was used, only the basic polypeptide stained positively for carbohydrate. For the 7S globulin, no carbohydrate group was detected using the PAS and con A-peroxidase tests. The 7S globulin was easily extracted with 0.10-0.15 M NaCl, whereas cocosin was extracted with 0.35 M NaCl. The N-terminal amino acid sequences of the 34 k band and 24 k band of cocosin were SVRSVNEFRXE and GLEETQ, respectively, and that of the 7S was EQEDPELQK.     

Vicilin-like storage globulin from buckwheat (Fagopyrum esculentum Moench) seeds

An 8S storage globulin from buckwheat seed, which resembles the structure and features common to the vicilin-like family of seed storage proteins, was analyzed for this paper. It was found that expression of the 8S globulin gene precedes that of the 13S globulin (the main buckwheat storage protein) and starts from an early stage of buckwheat seed development (9-11 days after flowering), continuing to accumulate throughout seed development to contribute approximately 7% of total seed proteins. This protein fraction might be more interesting for biotechnological application than the 13S buckwheat legumin consisting of 23-25 kDa subunits reported to be the major buckwheat allergen. A partial cDNA was also isolated, showing high homology with cDNAs coding for vicilin-like storage proteins from various plant species, and its expression profile throughout seed development as well as in different buckwheat tissues was analyzed.     

Storage proteins from Lathyrus sativus seeds

The proteins from Lathyrus sativus Linn. (chickling vetch or grass pea) seeds were investigated. Protein constitutes approximately 20% of the seed dry weight, >60% of which is composed by globulins and 30% by albumins. A single, 24 kDa polypeptide comprises more than half of the protein present in the albumin fraction. The globulins may be fractionated into three main components, which were named alpha-lathyrin (the major globulin), beta-lathyrin, and gamma-lathyrin. alpha-Lathyrin, with a sedimentation coefficient of approximately 18S, is composed of three main types of unglycosylated subunits (50-66 kDa), each of which produce, upon reduction, a heavy and a light polypeptide chain, by analogy with 11S. beta-Lathyrin, with a sedimentation coefficient of 13S, is composed by a relatively large number of subunits (8-66 kDa). Two major polypeptides are glycosylated and exhibit structural similarity with beta-conglutin from Lupinus albus. One of these possesses an internal disulfide bond. gamma-Lathyrin, with a sedimentation coefficient of approximately 5S, contains two interacting, unglycosylated polypeptides, with no disulfide bonds: the major 24 kDa albumin and the heavier (20 kDa) polypeptide chain of La. sativus lectin.     

Characterization of globulins from common vetch (Vicia sativa L.)

The proteins from Vicia sativa L. (common vetch) seeds were investigated. Protein comprises approximately 11.4% of the seed fresh weight, >50.8% of which is composed by globulins and 43.6% by albumins. The globulins may be fractionated into two main components, which were named alpha-vicinin (comprising 73% of the total globulin fraction, and hence >37% of the total seed protein) and beta-vicinin. Two minor globulin components are also present, gamma-vicinin and delta-vicinin. alpha-Vicinin, the legumin-like globulin, with a sedimentation coefficient of 10.6 S, is a nonglycosylated, disulfide-bond-containing globulin, composed of a group of subunits with molecular masses ranging from 50 to 78 kDa. Upon reduction, each of these subunits releases a heavy polypeptide chain (34-66 kDa) and a light polypeptide chain (21-23 kDa). beta-Vicinin, the vicilin-like globulin, with a sedimentation coefficient of 7.7 S, is a nonglycosylated globulin that contains no disulfide bonds and consists of two major polypeptides with molecular masses of 58 and 66 kDa. gamma-Vicinin is a minor, glycosylated, disulfide-bond-containing globulin. In the reduced form, it comprises six polypeptide chains with molecular masses of 12, 19, 21, 22, 23, and 31 kDa. Finally, delta-vicinin is a minor, highly glycosylated globulin that exhibits hemagglutinating activity. It is composed of a major 47 kDa polypeptide and two minor (33 and 38 kDa) polypeptides. N-terminal sequencing of the delta-vicinin 47 kDa polypeptide revealed no homology to any other known storage protein.     

Comparative proteomical analysis of zygotic embryo and endosperm from Coffea arabica seeds

During coffee seed development, proteins are predominantly deposited in cotyledons and in the endosperm. Reserve proteins of the 11S family are the most abundant globulins in coffee seeds, acting as a nitrogen source during roasting and guaranteeing flavor and aroma. The aim of the present study was to compare the protein profiles of endosperm and zygotic embryos of coffee seeds. Proteins were extracted from whole seed as well as from embryo and endosperm, separately. Total proteins were analyzed by two-dimensional electrophoresis (2-DE) followed by identification by mass spectrometry (MS). The most abundant spots observed in the gels of coffee seeds were excised, digested with trypsin, and identified by MS as subunits of the 11S globulin. Spots with identical pI and molecular masses were also observed in the protein profiles of coffee endosperm and embryo, indicating that 11S protein is also highly expressed in those tissues. Peptide sequence coverage of about 20% of the entire 11S globulin was obtained. Three other proteins were identified in the embryo and endosperm 2-DE profiles as a Cupin superfamily protein, an allergenic protein (Pru ar 1), exclusive to the endosperm 2D map, and a hypothetical protein, observed only in the zygotic embryo profile.     

Characterization of yam bean (Pachyrhizus erosus) proteins

Seed proteins from Mexican yam bean seeds (Pachyrhizus erosus L.) were sequentially extracted according to the Osborne classification. Albumins were the major fraction (52.1-31.0%), followed by globulins (30.7-27.5%). The minor protein fraction was prolamins (0.8%). Defatting with chloroform/methanol remarkably affected the distribution of protein solubility classes; albumins were the most affected fraction (4.3-17.5%). Electrophoretic patterns of albumins showed bands at 55, 40, 35, and 31 kDa. After reduction of the globulin fraction exhibited two triplets, one from 35 to 31 kDa and the second from 19 to 21 kDa, these could be compared to the acid and basic polypeptides of 11S-like proteins. Prolamins showed one band at 31 kDa, and glutelins after reduction showed three main bands at 52, 27, and 14 kDa. Trypsin inhibitors were assayed in saline extracts; the values found (1232-2608 IU/g of meal) were lower than those of other legumes. In general, yam bean seed proteins showed an excellent balance of all essential amino acids; albumins contain the highest amount of essential amino acids.     

One- and two-dimensional electrophoretic identification of IgE-binding polypeptides of Lupinus albus and other legume seeds

The prevalence of food allergies in the world population requires integrated approaches to identify new potential allergens, especially those of plant origin. The aim of this work was the allergen in vitro analysis of Lupinus albus seed proteome, a promising food protein source, and the assessment of IgE cross-reactivities with other more diffused legume species. A combination of one- and two-dimensional gel electrophoresis and immunoblotting analyses with specific IgGs for band identification and lupin-sensitized patients' circulating IgEs for allergenicity studies has been used. Two lupin proteins, namely, conglutin gamma and 11S globulin basic subunits, strongly reacted with all patients' sera. Also, cross-reactivities with the homologous polypeptides of other legume species were observed. Otherwise, no reaction at all was detected with a 2S-type lupin protein. This global electrophoretic approach has allowed the identification of a new potential lupin allergen and confirmed the cross-reactivity among the legume 11S globulin basic subunits.     

Cloning and characterization of an 11S legumin, Car i 4, a major allergen in pecan

Among tree nut allergens, pecan allergens remain to be identified and characterized. The objective was to demonstrate the IgE-binding ability of pecan 11S legumin and characterize its sequential IgE-binding epitopes. The 11S legumin gene was amplified from a pecan cDNA library and expressed as a fusion protein in Escherichia coli. The native 11S legumin in pecan extract was identified by mass spectrometry/mass spectrometry (MS/MS). Sequential epitopes were determined by probing the overlapping peptides with three serum pools prepared from different patients' sera. A three-dimensional model was generated using almond legumin as a template and compared with known sequential epitopes on other allergenic tree nut homologues. Of 28 patients tested by dot blot, 16 (57%) bound to 11S legumin, designated Car i 4. MS/MS sequencing of native 11S legumin identified 33 kDa acidic and 20-22 kDa basic subunits. Both pecan and walnut seed protein extracts inhibited IgE binding to recombinant Car i 4, suggesting cross-reactivity with Jug r 4. Sequential epitope mapping results of Car i 4 revealed weak, moderate, and strong reactivity of serum pools against 10, 5, and 4 peptides, respectively. Seven peptides were recognized by all three serum pools, of which two were strongly reactive. The strongly reactive peptides were located in three discrete regions of the Car i 4 acidic subunit sequence (residues 118-132, 208-219, and 238-249). Homology modeling of Car i 4 revealed significant overlapping regions shared in common with other tree nut legumins.     

Effects of Different Lipase Inactivation Treatments on Physicochemical Properties of Naked Oat Globulins

Lipase inactivation is an essential treatment for oat processing, because of the negative effects of lipase on nutrient preservation and storage extension. The effects of different lipase inactivation treatments including hot air roasting, infrared roasting, normal‐pressure steaming, and high‐pressure steaming on the physicochemical properties of oat globulins were investigated. Results showed that normal‐pressure steaming had little effect on solubility of oat globulins; hot air roasting increased foaming capacity of oat globulins but did not change their foaming stability; and all the inactivation treatments increased the surface hydrophobicity and content of total sulfhydryls of oat globulin but decreased exposed sulfhydryl groups. In addition, oat globulin granules from the hot air roasting treatment were distributed more evenly in oat globulin powder compared with the control group. All treatments except normal‐pressure steaming changed the molecular weight of oat globulin subunits, which made the bands of 66,000 and 45,000 disappear from SDS‐PAGE. These results indicated that normal‐pressure steaming was ideal to maintain good solubility of oat globulins, and hot air roasting was ideal to maintain relatively good foaming properties. The treatments changed physicochemical properties of oat globulins by influencing protein aggregation and subunit composition that resulted in different content of sulfhydryl groups and surface hydrophobicity.     

Genetic variation in pea seed globulin composition

A quantitative characterization of seeds from 59 pea (Pisum sativum L.) lines and relative taxa with various external characteristics and wide geographical origin was performed to explore the genetic variation of pea concerning its starch and protein contents and globulin composition. Pea lines, which produce round, wrinkled, flat, and round-dimpled seeds, have starch as the major reserve, with an average content of 46%. Protein content varied from 13.7 to 30.7% of the seed dry matter, with an overall average of 22.3%. Densitometric quantification of the individual globulins (legumin, vicilin, convicilin, and globulin-related proteins) based on SDS-PAGE gels showed no lines lacking any particular globulin. Among the lines tested, variation was shown in both their total globulins content and their globulin composition. The total globulin content ranged from 49.2 to 81.8% of the total pea protein extract (TPPE). Legumin content varied between 5.9 and 24.5% of the TPPE. Vicilin was the most abundant protein of pea, and its content varied between 26.3 and 52.0% of the TPPE. Both processed and nonprocessed vicilins occurred. The processed vicilin was the predominant one, with values between 17.8 and 40.8%, whereas the nonprocessed ones constituted between 3.1 and 13.5% of the TPPE. Convicilin was the least abundant globulin, and its content ranged from 3.9 to 8.3%. Finally, the globulin-related proteins were present in amounts ranging from 2.8 to 17.3%. They were less abundant in comparison with legumin and vicilin, but they showed the largest relative variation of the four globulin classes. Correlations between the different external characteristics and globulin composition were determined. Comparison with soybean showed that pea lines show more variety in the abundance of globulin proteins, enabling a wider range of food application.     

Characterization of the soluble allergenic proteins of cashew nut (Anacardium occidentale L.)

The allergens associated with cashew food allergy have not been well-characterized. We sought to identify the major allergens in cashew nut by performing IgE immunoblots to dissociated and reduced or nonreduced cashew protein extracts, followed by sequencing of the peptides of interest. Sera from 15 subjects with life-threatening reactions to cashews and 8 subjects who tolerate cashews but have life-threatening reactions to other tree nuts were compared. An aqueous cashew protein extract containing albumin/globulin was separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and subjected to IgE immunoblotting using patient sera. Selected IgE reactive bands were subjected to N-terminal amino acid sequencing. Each of the 15 sera from cashew-allergic subjects showed IgE binding to the cashew protein extract. The dominant IgE-binding antigens in the reduced preparations included peptides in the 31-35 kD range, consistent with the large subunits of the major storage 13S globulin (legumin-like protein). Low-molecular-weight polypeptides of the 2S albumin family, with similarity to the major walnut allergen Jug r 1, also bound IgE. The sera from eight patients who tolerate cashew but displayed allergies to other tree nuts showed only minimal or no IgE binding to cashew. Cashew food allergy is associated with the presence of IgE directed against the major seed storage proteins in cashew, including the 13S globulin (legumin group) and 2S albumins, both of which represent major allergen classes in several plant seeds. Thus, the legumin-group proteins and 2S albumins are again identified as major food allergens, which will help further research into seed protein allergenicity.     

Effect of pH and ionic strength modifications on thermal denaturation of the 11S globulin of sunflower (Helianthus annuus)

Helianthinin, the main storage protein of sunflowers, has low water solubility and does not form a gel when heated; this behavior is different from other 11S globulins and limits its food applications. To understand this particular behavior, changes on helianthinin association-dissociation state induced by modifications in pH and ionic strength were analyzed. The influence of these different medium conditions on its thermal stability and tendency to form aggregates was also studied. Helianthinin behavior at different pH values and ionic strengths is similar to other 11S globulins except that it remains in a trimeric form at pH 11. Helianthinin thermal stability is higher than other 11S globulins but is lower than oat 11S globulin. Alkaline pH produces a 10 degrees C decrease of its denaturation temperature and also of the cooperativity of denaturation process, but it does not affect the denaturation activation energy. The decrease in thermal stability with the pH increase is also manifested by its tendency to form aggregates by SH/SS interchange reactions. When thermal treatments at alkaline pH are performed, all helianthinin subunits form aggregates, characterized by a higher proportion of beta-polypeptides than alpha-polypeptides, which is an indication that aggregation is accompanied by dissociation. Treatments at 80 degrees C are sufficient to induce aggregation but not to produce denaturation, and in these conditions hexameric forms remain after the treatment.     

Physicochemical properties of native and recombinant mungbean (Vigna radiata L. Wilczek) 8S globulins and the effects of the N-linked glycans

We have previously cloned and characterized the cDNAs of three isoforms of the 8S globulin of mungbean, expressed the major 8Salpha isoform in Escherichia coli, and purified and successfully crystallized it (Bernardo, A. E. N.; Garcia, R. N.; Adachi, M.; Angeles, J. G. C.; Kaga, A; Ishimoto, M.; Utsumi, S.; Tecson-Mendoza, E. M. J. Agric. Food Chem. 2004, 52, 2552-2560). Herein, we report the physicochemical and emulsifying properties of the native 8S and recombinant 8Salpha globulin or vicilin. The circular dichroism spectra analysis of the native 8S and recombinant 8Salpha globulins revealed that the recombinant 8Salpha formed a secondary structure close to that of the native 8S. Further, gel filtration analysis showed that 8Salpha was able to assemble into trimers. The native 8S and recombinant 8Salpha globulins were soluble at pH 3.4 and at pH 7.4-9.0 at low ionic strength, mu = 0.08. Interestingly, the native 8S was more soluble at pH 7.0 and pH 7.4 than the recombinant 8Salpha at mu = 0.08. Both forms were very soluble at pH 3.4-9.0 at high ionic strength, mu = 0.50. The native form exhibited a higher T(m) (69.2, 79.5, and 83.8 degrees C) than the recombinant form (65.6, 71.6, 77.5 degrees C) at mu = 0.1, 0.2, and 0.5, respectively. The recombinant form was found to have greater surface hydrophobicity than the native form. There was little difference in the emulsifying ability between the native 8S and 8Salpha at pH 3.4 and pH 7.6. The results indicate that the presence of N-linked glycans is not essential in the assembly and stable conformation of the mungbean vicilin. However, the N-linked glycans might have contributed to the higher solubility at low ionic strength, greater thermal stability, and decreased surface hydrophobicity of the native vicilin as compared to the recombinant 8Salpha. On the other hand, the N-linked glycans showed little effect on the emulsifying ability of the protein.     

Characterization and crystallography of recombinant 7S globulins of Adzuki bean and structure-function relationships with 7S globulins of various crops

The recombinant proteins Adzuki 7S1, Adzuki 7S2, and Adzuki 7S3 were prepared through the Escherichia coli expression systems of three kinds of adzuki bean cDNAs. The recombinant proteins exhibited intrinsic thermal stabilities, surface hydrophobicities, and solubilities, although the homology of their amino acid sequences ranged from 95-98%. To understand why these individual proteins exhibited different properties, their three-dimensional structures were elucidated. The three proteins were successfully crystallized, and the three-dimensional structures of Adzuki 7S1 and Adzuki 7S3 were determined. The properties and structures of these two proteins were comprehensively compared with those of recombinant 7S globulins (soybean beta-conglycinins beta and alpha'c and mungbean 8Salpha) reported previously. It was likely that cavity sizes, hydrogen bonds, salt bridges, hydrophobic interactions, and lengths of loops determine the thermal stabilities of 7S globulins, and results indicated that cavity sizes strongly contribute to such stability. Surface hydrophobicity was also found to be determined not only by distributions of hydrophobic residues on the molecular surface. Furthermore, solubility at neutral and weak alkaline pH values at mu = 0.08 was found to be dominantly influenced by the electrostatic surface potentials.     

Effect of sucrose on functional properties of soy globulins: adsorption and foam characteristics

In this contribution, we have analyzed the effect of sucrose on dynamic interfacial (dynamic surface pressure and surface dilatational properties) and foaming (foam capacity and foam stability) characteristics of soy globulins (7S and 11S). The protein (at 1 x 10(-3), 1 x 10(-2), 0.1, and 1 wt %) and sucrose (at 0, 0.25, 0.5, and 1.0 M) concentrations in aqueous solution and the pH (at 5 and 7), and ionic strength (at 0.05 and 0.5 M) were analyzed as variables. The temperature was maintained constant at 20 degrees C. We have observed the following. (i) The dynamics of adsorption (presence of a lag period, diffusion, and penetration at the air-water interface) of soy globulins depend on the peculiar molecular features of proteins (7S or 11S soy globulin) and the level of association/dissociation of these proteins by varying the pH and ionic strength, as well as the effect of sucrose in the aqueous phase on the unfolding of the protein. The rate of adsorption increases with the protein concentration in solution, at pH 7 compared to pH 5, at high ionic strength, and in the absence of sucrose. (ii) The surface dilatational properties reflect the fact that soy globulin adsorbed films exhibit viscoelastic behavior. The surface dilatational modulus increases at pH 7 compared to pH 5, but decreases with the addition of sucrose into the aqueous phase. (iii) The rate of adsorption and surface dilatational properties (surface dilatational modulus and phase angle) during adsorption at the air-water interface play an important role in the formation of foams generated from aqueous solutions of soy globulins. (iv) The increased interfacial adsorption (at high surface pressures) and the combined effects of interfacial adsorption and interfacial interactions between adsorbed soy globulin molecules (at high surface dilatational modulus) can explain the higher stability of the foam, with few exceptions.     

Surface physicochemical properties of globulin-P amaranth protein

Globulin-P, the polymerized 11S amaranth globulin, is composed of 280 kDa unitary molecules (UM, 23%) and aggregates larger than 500 kDa (A, 70%). Antibodies against these proteins were prepared to study their surface characteristics and to assess their homology with other storage proteins. Results showed that globulin-P unitary molecules and aggregates had similar reactive surfaces. A polypeptide of 56 kDa was found to be the most reactive to the antibodies assayed, followed by the acidic polypeptides. Such results support previous information, according to which these polypeptides appeared to be the most exposed on the molecule surface. Globulin-P fraction presented cross-reactivity with the remaining amaranth protein fractions: 11S-globulin, glutelins, and albumins. Globulin-P and 11S-globulin showed similar reactive surfaces whereas glutelin and albumins presented a lower cross-reactivity. The reactivity of the glutelin fraction depended on its sequence. Globulin-P fraction presented cross-reactivity with quinoa globulins, and to a lesser extent with globulins of sunflower and rice. Moreover, the anti-Gp serum was unable to detect either conformational or sequence epitopes in globulins of soybean, wheat, buckwheat, rice, and rye.     

Crystal structures and structural stabilities of the disulfide bond-deficient soybean proglycinin mutants C12G and C88S

The constituent subunits of seed storage protein 11S globulin have two disulfide bonds that are common among 11S globulins from legume and nonlegume seeds. In the case of the A1aB1b subunit of soybean 11S globulin, glycinin, Cys12-Cys45 and Cys88-Cys298 are observed by X-ray crystallography. The significance of these two disulfide bonds for structural stability was investigated by mutagenesis of Cys12 to Gly and of Cys88 to Ser. The disulfide bond-deficient mutants C12G and C88S could form the correct conformations identical to that of the wild-type proglycinin except in the vicinities of the mutation sites C12 and C88 as shown by their crystal structures. Thermal stability monitored by differential scanning calorimetry of the mutants indicated that the contribution of these disulfide bonds to the thermal stability of proglycinin A1aB1b is low, although there is a small difference in the extent of the contribution between the two disulfide bonds (Cys12-Cys45 > Cys88-Cys298). The contribution of Cys88-Cys298 to the resistance of proglycinin A1aB1b to proteinase digestion is higher than that of Cys12-Cys45. Possible effects of structure on the different properties of C12G and C88S are discussed.     

Proteins Extracted from Defatted Wheat Germ: Nutritional and Structural Properties

The main by‐product of the wheat germ oil extraction process is a defatted wheat germ meal, which has a relatively high protein content, making it an attractive and promising source of vegetable proteins. Four protein fractions (albumin, globulin, prolamine, and glutelin) and protein isolate from defatted wheat germ flour (DWGF) were fractionated and then characterized by amino acid analysis, SDS‐PAGE, and differential scanning calorimetry (DSC). Albumin was the major fraction (34.5%) extracted, followed by globulin (15.6%), glutelin (10.6%), and prolamine (4.6%). Protein isolate was mainly composed of albumin and globulin. These protein fractions and protein isolate showed an excellent balance of all essential amino acids, with a relatively high level of glutamic acid, arginine, leucine, and glycine, whereas cystine was lacking. All the estimated nutritional quality parameters based on amino acids composition showed that defatted wheat germ proteins had good nutritional quality. Nonreduced and reduced SDS‐PAGE analyses showed that S‐S bonds ere deficient in the structure of wheat germ proteins. The albumin fraction consisted of 19 major polypeptide bands with M_r 14,000–84,000. The globulin fraction showed four distinct polypeptides or polypeptide group bands with M_r 55,000, 37,000–43,000, 24,000, and 12,000–20,000, which may be the components of the 8S‐type and 11S‐like proteins. The prolamine fraction showed a predominant doublet‐like band at M_r 17,000–16,000, while the glutelin fraction showed five major polypeptide bands with M_r 39,000, 20,000, 18,000, 17,000, and 14,000. Protein isolate and DWGF showed very similar SDS‐PAGE patterns. Except for prolamine and glutelin fractions without detectable calorimetric response, the globulin fraction possessed the highest thermal stability (T_d = 83.80°C, ΔH =1.36 J/g ), followed by protein isolate (T_d = 80.05°C, ΔH = 0.76 J/g), while the albumin fraction was lowest (T_d = 69.72°C, ΔH = 0.53 J/g). The findings on defatted wheat germ proteins are important for their potential application as functional food ingredients.     

Vigna vexillata (L.) A. Rich. seed proteins: heterogeneity in subunits of globulin fraction

Forty-six accessions of Vigna vexillata from Africa, America and Australia were screened for variability in globulin protein fraction by using SDS-PAGE under reducing and non-reducing conditions. The globulin fraction was composed of several bands clustering in two size fractions, both of which were polymorphic. The high molecular weight fraction was constituted by one or two subunits, while the fraction of lower molecular weight exhibited from two to four bands. Two single types were found within the collection. Due to the observed polymorphism only the subunit at 52 kD was species-specific. Southeastern Africa proved to be the region with the highest diversity for Vigna vexillata. Different frequencies of the globulin patterns were observed between the African and American groups of accessions. No significant differences were found comparing the distribution of the globulin types between the varieties vexillata and angustifolia.