Mass spectrometry of in-gel digests reveals differences in amino acid sequences of high-molecular-weight glutenin subunits in spelt and emmer compared to common wheat.

High-molecular-weight glutenin subunits (HMW-GS) play an important role for the baking quality of wheat. The ancient wheats emmer and spelt differ in their HMW-GS pattern compared to modern common wheat and this might be one reason for their comparatively poor baking quality. The aim of this study was to elucidate similarities and differences in the amino acid sequences of two 1Bx HMW-GS of common wheat, spelt and emmer. First, the sodium dodecyl polyacrylamide gel electrophoresis (SDS-PAGE) system was optimized to separate common wheat, spelt and emmer Bx6 and Bx7 from other HMW-GS (e.g., 1Ax and 1By) in high concentrations. The in-gel digests of the Bx6 and Bx7 bands were analyzed by untargeted LC-MS/MS experiments revealing different UniProtKB accessions in spelt and emmer compared to common wheat. The HMW-GS Bx6 and Bx7, respectively, of emmer and spelt showed differences in the amino acid sequences compared to those of common wheat. The identities of the peptide variations were confirmed by targeted LC-MS/MS. These peptides can be used to differentiate between Bx6 and Bx7 of spelt and emmer and Bx6 and Bx7 of common wheat. The findings should help to increase the reliability and curation status of wheat protein databases and to understand the effects of protein structure on the functional properties. Graphical abstract.

Catcher of the Rye: Detection of Rye, a Gluten-Containing Grain, by LC-MS/MS.

Rye, wheat, and barley contain gluten, proteins that trigger immune-mediated inflammation of the small intestine in people with celiac disease (CD). The only treatment for CD is a lifelong gluten-free diet. To be classified as gluten-free by the World Health Organization the gluten content must be below 20 mg/kg, but Australia has a more rigorous standard of no detectable gluten and not made from wheat, barley, rye, or oats. The purpose of this study was to devise an LC-MS/MS method to detect rye in food. An MS-based assay could overcome some of the limitations of immunoassays, wherein antibodies often show cross-reactivity and lack specificity due to the diversity of gluten proteins in commercial food and the homology between rye and wheat gluten isoforms. Comprehensive proteomic analysis of 20 rye cultivars originating from 12 countries enabled the identification of a panel of candidate rye-specific peptide markers. The peptide markers were assessed in 16 cereal and pseudocereal grains, and in 10 breakfast cereals and 7 snack foods. One of two spelt flours assessed was contaminated with rye at a level of 2%, and trace levels of rye were found in a breakfast cereal that should be gluten-free based on its labeled ingredients.

Phase separation dynamics of gluten protein mixtures.

We investigate by time-resolved synchrotron ultra-small X-ray scattering the dynamics of liquid-liquid phase-separation (LLPS) of gluten protein suspensions following a temperature quench. Samples at a fixed concentration (237 mg ml-1) but with different protein compositions are investigated. In our experimental conditions, we show that fluid viscoelastic samples depleted in polymeric glutenin phase-separate following a spinodal decomposition process. We quantitatively probe the late stage coarsening that results from a competition between thermodynamics that speeds up the coarsening rate as the quench depth increases and transport that slows down the rate. For even deeper quenches, the even higher viscoelasticity of the continuous phase leads to a "quasi" arrested phase separation. Anomalous phase-separation dynamics is by contrast measured for a gel sample rich in glutenin, due to elastic constraints. This work illustrates the role of viscoelasticity in the dynamics of LLPS in protein dispersions.

Assessing the Utility of Multiplexed Liquid Chromatography-Mass Spectrometry for Gluten Detection in Australian Breakfast Food Products.

Coeliac disease (CD) is an autoimmune disorder triggered by the ingestion of gluten that is associated with gastrointestinal issues, including diarrhea, abdominal pain, and malabsorption. Gluten is a general name for a class of cereal storage proteins of wheat, barley, and rye that are notably resistant to gastrointestinal digestion. After ingestion, immunogenic peptides are subsequently recognized by T cells in the gastrointestinal tract. The only treatment for CD is a life-long gluten-free diet. As such, it is critical to detect gluten in diverse food types, including those where one would not expect to find gluten. The utility of liquid chromatography-mass spectrometry (LC-MS) using cereal-specific peptide markers to detect gluten in heavily processed food types was assessed. A range of breakfast products, including breakfast cereals, breakfast bars, milk-based breakfast drinks, powdered drinks, and a savory spread, were tested. No gluten was detected by LC-MS in the food products labeled gluten-free, yet enzyme-linked immunosorbent assay (ELISA) measurement revealed inconsistencies in barley-containing products. In products containing wheat, rye, barley, and oats as labeled ingredients, gluten proteins were readily detected using discovery proteomics. Panels comprising ten cereal-specific peptide markers were analyzed by targeted proteomics, providing evidence that LC-MS could detect and differentiate gluten in complex matrices, including baked goods and milk-based products.

Effects of Ultrasonic-Assisted Extraction on the Physicochemical Properties of Different Walnut Proteins.

The effects of ultrasonic-assisted extraction (UAE, 200 W, 20 min) on the yield and physicochemical properties of different walnut proteins (WNPs, including albumin, globulin, and glutelin) were investigated. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis indicated that UAE could result in protein molecular fragmentation of albumin, but did not affect the major bands of globulin and glutelin. The CD spectra demonstrated that different WNPs obtained by UAE had different changes in their secondary structure. Under UAE, there was an increase in surface hydrophobicity (H0) of albumin and gluten and no change in the fluorescence intensity, while decreases were observed in the H0 and fluorescence intensity of globulin; and the contents of total and surface free sulfhydryl in albumin dramatically decreased. UAE reduced the size of the particles and the dimension of the microstructures in albumin and gluten, indicating that ultrasound could unfold protein aggregates. In addition, UAE increased the solubility, emulsifying activity (EA), foaming capacity (FC), and foam stability (FS) of the obtained proteins. The above results indicate that ultrasound extraction is a promising approach to improve the extraction yield and properties of walnut proteins.

Molecular and Functional Properties of Protein Fractions and Isolate from Cashew Nut (Anacardium occidentale L.).

Some molecular and functional properties of albumin (83.6% protein), globulin (95.5% protein), glutelin (81.3% protein) as well as protein isolate (80.7% protein) from cashew nut were investigated. These proteins were subjected to molecular (circular dichroism, gel electrophoresis, scanning electron microscopy) and functional (solubility, emulsification, foaming, water/oil holding capacity) tests. Cashew nut proteins represent an abundant nutrient with well-balanced amino acid composition and could meet the requirements recommended by FAO/WHO. SDS-PAGE pattern indicated cashew nut proteins were mainly composed of a polypeptide with molecular weight (MW) of 53 kDa, which presented two bands with MW of 32 and 21 kDa under reducing conditions. The far-UV CD spectra indicated that cashew proteins were rich in ß-sheets. The surface hydrophobicity of the protein isolate was higher than that of the protein fractions. In pH 7.0, the solubility of protein fractions was above 70%, which was higher than protein isolate at any pH. Glutelin had the highest water/oil holding capacity and foaming properties. Protein isolate displayed better emulsifying properties than protein fractions. In summary, cashew nut kernel proteins have potential as valuable nutrition sources and could be used effectively in the food industry.

Report- Immunological study of different fraction of wheat proteins.

Wheat allergy specifically refers to the adverse reaction involving IgE antibody to one or more protein fraction of wheat such as albumin, globulin, gliadin and glutenin (gluten). The majority of IgE-mediated reactions to wheat involve albumin and globulin fraction while gluten (gliadin & glutenin) also cause allergy (Celiac disease). Allergic reactions to wheat may be caused by ingestion of wheat containing foods or inhalation of flour (Bakers asthma). The present study was an effort to explore the antibody response of different proteins present in wheat. ELISA results revealed that the antibody response for albumin varied from 0.92-1.78, whereas, for globulin ranged from 1.39-1.60. Antibody response against glutenin and gliadin ranged from 0.57-1.05 and 0.98-1.95 respectively, among the different varieties of wheat. All the tested wheat varieties showed the significant difference antibody response against the different fractions of protein.

Improved Method for Reliable HMW-GS Identification by RP-HPLC and SDS-PAGE in Common Wheat Cultivars.

The accurate identification of alleles for high-molecular weight glutenins (HMW-GS) is critical for wheat breeding programs targeting end-use quality. RP-HPLC methods were optimized for separation of HMW-GS, resulting in enhanced resolution of 1By and 1Dx subunits. Statistically significant differences in retention times (RTs) for subunits corresponding to HMW-GS alleles were determined using 16 standard wheat cultivars with known HMW-GS compositions. Subunits that were not identified unambiguously by RP-HPLC were distinguished by SDS-PAGE or inferred from association with linked subunits. The method was used to verify the allelic compositions of 32 Korean wheat cultivars previously determined using SDS-PAGE and to assess the compositions of six new Korean cultivars. Three cultivars contained subunits that were identified incorrectly in the earlier analysis. The improved RP-HPLC method combined with conventional SDS-PAGE provides for accurate, efficient and reliable identification of HMW-GS and will contribute to efforts to improve wheat end-use quality.

Identification of coeliac disease triggering glutenin peptides in adults.

OBJECTIVE: Coeliac disease affects approximately 1% of Northern American and European populations. It is caused by an inappropriate immune response to dietary gluten. Gluten comprises of two major protein fractions: gliadins and glutenins. Glutenins have recently been found to be toxic to coeliac individuals. Proliferation assays suggest in some but not all paediatric coeliac individuals there may be immunological stimulation with high molecular weight (HMW) glutenins. Less evidence pertains to low molecular weight (LMW) glutenins. The aim is to assess adaptive, T-cell driven, and innate immune response in adult coeliac individuals towards HMW glutenin peptide, glut04, and LMW glutenin peptide, glt156. MATERIALS AND METHODS: Coeliac patients were recruited attending endoscopy for routine monitoring. Adaptive immune response towards glut04 and glt156 was measured by proliferation assays and measurement of interferon-γ secretion in 28 T-cell lines. The innate immune response was assessed by measurement of enterocyte cell height (ECH) in coeliac small intestinal biopsies following overnight incubation in organ culture chambers in a further nine individuals. RESULTS: There were 3/28 and 2/28 positive proliferation results using gluten-sensitive T-cells with glut04 and glt156, respectively. All coeliac biopsies tested in organ culture chambers demonstrated clear reduction in ECH with peptic-tryptic digest of whole industrial gluten, glut04 and glt156 when compared to negative control ovalbumin (p < 0.005). Three individuals had both T-cell and organ culture study data. Their proliferation assays showed no stimulation of the T-cells. CONCLUSIONS: This study demonstrates glutenin epitopes glut04 and glt156, while minor T-cell epitopes, are important in their ability to trigger the innate immune response.

Production of hydrophobic amino acids from biobased resources: wheat gluten and rubber seed proteins.

Protein hydrolysis enables production of peptides and free amino acids that are suitable for usage in food and feed or can be used as precursors for bulk chemicals. Several essential amino acids for food and feed have hydrophobic side chains; this property may also be exploited for subsequent separation. Here, we present methods for selective production of hydrophobic amino acids from proteins. Selectivity can be achieved by selection of starting material, selection of hydrolysis conditions, and separation of achieved hydrolysate. Several protease combinations were applied for hydrolysis of rubber seed protein concentrate, wheat gluten, and bovine serum albumin (BSA). High degree of hydrolysis (>50 %) could be achieved. Hydrophobic selectivity was influenced by the combination of proteases and by the extent of hydrolysis. Combination of Pronase and Peptidase R showed the highest selectivity towards hydrophobic amino acids, roughly doubling the content of hydrophobic amino acids in the products compared to the original substrates. Hydrophobic selectivity of 0.6 mol-hydrophobic/mol-total free amino acids was observed after 6 h hydrolysis of wheat gluten and 24 h hydrolysis of rubber seed proteins and BSA. The results of experiments with rubber seed proteins and wheat gluten suggest that this process can be applied to agro-industrial residues.

Molecular cloning, phylogenetic analysis, and expression profiling of endoplasmic reticulum molecular chaperone BiP genes from bread wheat (Triticum aestivum L.).

BACKGROUND: The endoplasmic reticulum chaperone binding protein (BiP) is an important functional protein, which is involved in protein synthesis, folding assembly, and secretion. In order to study the role of BiP in the process of wheat seed development, we cloned three BiP homologous cDNA sequences in bread wheat (Triticum aestivum), completed by rapid amplification of cDNA ends (RACE), and examined the expression of wheat BiP in wheat tissues, particularly the relationship between BiP expression and the subunit types of HMW-GS using near-isogenic lines (NILs) of HMW-GS silencing, and under abiotic stress. RESULTS: Sequence analysis demonstrated that all BiPs contained three highly conserved domains present in plants, animals, and microorganisms, indicating their evolutionary conservation among different biological species. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) revealed that TaBiP (Triticum aestivum BiP) expression was not organ-specific, but was predominantly localized to seed endosperm. Furthermore, immunolocalization confirmed that TaBiP was primarily located within the protein bodies (PBs) in wheat endosperm. Three TaBiP genes exhibited significantly down-regulated expression following high molecular weight-glutenin subunit (HMW-GS) silencing. Drought stress induced significantly up-regulated expression of TaBiPs in wheat roots, leaves, and developing grains. CONCLUSIONS: The high conservation of BiP sequences suggests that BiP plays the same role, or has common mechanisms, in the folding and assembly of nascent polypeptides and protein synthesis across species. The expression of TaBiPs in different wheat tissue and under abiotic stress indicated that TaBiP is most abundant in tissues with high secretory activity and with high proportions of cells undergoing division, and that the expression level of BiP is associated with the subunit types of HMW-GS and synthesis. The expression of TaBiPs is developmentally regulated during seed development and early seedling growth, and under various abiotic stresses.

Effects of zein extractions on the structural properties of SPI-zein composite gels: Implications for gluten-free plant-based products.

The growing global interest in physical and environmental health has led to the development of plant-based products. Although soy protein and wheat gluten are commonly utilized, concerns regarding gluten-related health issues have driven exploration into alternative proteins. Zein has emerged as a promising option. This research investigated the impact of extraction methods on zein characteristics and the structures of SPI-zein composite gels. Different extraction methods yielded zein with protein contents ranging from 48.12 % to 64.34 %. Ethanol-extracted Z1 and Z3, obtained at different pH conditions, exhibited zeta potential of -3.25 and 5.43 mV, respectively. They displayed similar characteristics to commercial zein and interacted comparably in composite gels. Conversely, alkaline-extracted Z2 had a zeta potential of -2.37 mV and formed distinct gels when combined with SPI. These results indicated that extraction methods influence zein behaviour in composite gels, offering possibilities for tailored formulations and expanding zein's applications, particularly in gluten-free plant-based products.

Evaluation of extraction solutions for biochemical analyses of the proteins in rice grains.

The influence of different extraction solutions on the proteins extracted from rice grains was investigated. The largest amounts of salt-soluble proteins were extracted with solutions supplemented with Tris-HCl at pH 8.0. Rice allergens were analyzed by multiplex immunodetection. Except for α-globulin extracted with the solutions at pH 8.0, which showed a low-molecular-weight band besides the main band, no significant solution-dependent difference among the allergens was found. Total proteins were extracted with four kinds of solution. The extraction of the basic subunit of glutelin was found to be SDS-dependent, and more protein was obtained with extraction solutions supplemented with SDS. The contents of α-globulin and α-amylase/trypsin inhibitors were higher in the extracts without SDS than with SDS. We conclude from the present data that, in order to obtain comparable data from rice grain salt-soluble and total protein analyses, differences in the protein extraction efficiency of solutions used should be taken into consideration.

Amino acid profiles and quality from lotus seed proteins.

BACKGROUND: Protein composition, amino acid profile and nutritional value of the lotus seed and its Osborne fractions were investigated. The seed was rich in protein with 19.85%, and showed well balanced amino acid composition compared with FAO/WHO pattern, Its nutritive properties were similar to those observed in the reference soybean protein. Phenylalanine, tyrosine, leucine and lysine were the limiting amino acids in the seed proteins. The albumin and globulin were the main protein fraction, the amino acid profile and nutritional value were close to the seed protein. RESULTS: Changes in transition temperature and thermal stability were observed through different solvent extractions. Albumin possessed the predominant thermal stability (81.4 °C) followed by globulin (74.49 °C), prolamin (69 °C) and glutelin (65.6 °C). So, solvent compositions influence the profile of AAs and their nutritive value, and aqueous solvent with 0.1 mol L⁻¹ NaCl was an efficient protein solubiliser. CONCLUSION: The results indicated that the extraction processes influenced the lotus seed protein quality and thermal stability. Overall, the study revealed that the lotus seed protein was nutritionally well-balanced protein and might be of significant importance in the formulation of diets for humans.

Comparative efficiency of different methods of gluten extraction in indigenous varieties of wheat.

The present study investigated six varieties of locally grown wheat (Lasani, Sehar, Miraj-08, Chakwal-50, Faisalabad-08 and Inqlab) procured from Punjab Seed Corporation, Lahore, Pakistan for their proximate contents. On the basis of protein content and ready availability, Faisalabad-08 (FD-08) was selected to be used for the assessment of comparative efficiency of various methods used for gluten extraction. Three methods, mechanical, chemical and microbiological were used for the extraction of gluten from FD-08. Each method was carried out under ambient conditions using a drying temperature of 55 degrees C. Mechanical method utilized four different processes viz:- dough process, dough batter process, batter process and ethanol washing process using standard 150 mesh. The starch thus obtained was analyzed for its proximate contents. Dough batter process proved to be the most efficient mechanical method and was further investigated using 200 and 300 mesh. Gluten content was determined using sandwich omega-gliadin enzyme-linked immunosorbent assay (ELISA).The results of dough batter process using 200 mesh indicated a starch product with gluten content of 678 ppm. Chemical method indicated high gluten content of more than 5000 ppm and the microbiological method reduced the gluten content from 2500 ppm to 398 ppm. From the results it was observed that no gluten extraction method is viable to produce starch which can fulfill the criteria of a gluten free product (20 ppm).

What is in a beer? Proteomic characterization and relative quantification of hordein (gluten) in beer.

The suite of prolamin proteins present in barley flour was characterized in this study, in which we provide spectral evidence for 3 previously characterized prolamins, 8 prolamins with only transcript evidence, and 19 genome-derived predicted prolamins. An additional 9 prolamins were identified by searching the complete spectral set against an unannotated translated EST database. Analyses of wort, the liquid extracted from the mashing process during beer production, and beer were undertaken and a similar suite of prolamins were identified. We have demonstrated by using tandem mass spectrometry that hordeins are indeed present in beer despite speculation to the contrary. Multiple reaction monitoring (MRM) mass spectrometry was used for the rapid analyses of hordein in barley (Hordeum vulgare L.) beer. A selection of international beers were analyzed and compared to the results obtained with hordein deletion beers. The hordein deletion beers were brewed from grains carrying mutations that prevented the accumulation of either B-hordeins (Risø 56) or C-hordeins (Risø 1508). No intact C-hordeins were detected in beer, although fragments of C-hordeins were present in wort. Multiple reaction monitoring analysis of non-barley based gluten (hordein)-free beers targeting the major hordein protein families was performed and confirmed the absence of hordein in several gluten-free commercial beers.

Novel variants of HMW glutenin subunits from Aegilops section Sitopsis species in relation to evolution and wheat breeding.

BACKGROUND: High molecular weight glutenin subunits (HMW-GSs), encoded by the genes at Glu-1 loci in wheat and its related species, are significant in the determination of grain processing quality. However, the diversity and variations of HMW-GSs are relatively low in bread wheat. More interests are now focused on wheat wild relatives in Triticeae. The genus Aegilops represents an important germplasm for novel HWM-GSs and other useful genes for wheat genetic improvement. RESULTS: Six novel Glu-1 alleles and HMW-GSs were identified and characterized from three species of Aegilops section Sitopsis (S genome). Both open reading frames (ORFs) and promoter regions of these Glu-1 alleles were sequenced and characterized. The ORFs of Sitopsis Glu-1 genes are approximately 2.9 kb and 2.3 kb for x-type and y-type subunits, respectively. Although the primary structures of Sitopsis HMW-GSs are similar to those of previously reported ones, all six x-type or y-type subunits have the large fragment insertions. Our comparative analyses of the deduced amino acid sequences verified that Aegilops section Sitopsis species encode novel HMW-GSs with their molecular weights larger than almost all other known HMW-GSs. The Glu-1 promoter sequences share the high homology among S genome. Our phylogenetic analyses by both network and NJ tree indicated that there is a close phylogenetic evolutionary relationship of x-type and y-type subunit between S and D genome. CONCLUSIONS: The large molecular weight of HMW-GSs from S genome is a unique feature identified in this study. Such large subunits are resulted from the duplications of repetitive domains in Sitopsis HMW-GSs. The unequal crossover events are the most likely mechanism of variations in glutenin subunits. The S genome-encoded subunits, 1Dx2.2 and 1Dx2.2* have independent origins, although they share similar evolutionary mechanism. As HMW-GSs play a key role in wheat baking quality, these large Sitopsis glutenin subunits can be used as special genetic resources for wheat quality improvement.

Fast wheat variety classification by capillary gel electrophoresis-on-a-chip after single-step one-grain high molecular weight glutenin extraction.

Wheat variety identification based on one-step single-grain wheat extraction and fast capillary gel electrophoresis-on-a-chip (CGE-on-a-chip) analyses was evaluated for 15 different wheat varieties grown in Austria. The results of the capillary-based separation system were compared to the internationally accepted method from the International Union for the Protection of New Varieties of Plants which is based on time-consuming sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) analysis. Comparable protein patterns were observed making the CGE-on-a-chip system a promising tool for high-throughput analysis in food control. For the development of a robust method protein extraction, shelf life of wheat extracts and the instrument's variability were evaluated. It turned out that a one-step single-grain wheat extraction allowed the sample to be stored at 4 °C for up to 4 weeks without losing any valuable protein information. Furthermore, the technical variation of the whole method is very low making the biological variation of the selected wheat grains the only uncertain factor. Additionally, two unsupervised statistical methods (hierarchical cluster analysis and principal component analysis) were used for variety identification. Identification was successful for a reduced data set of 14 samples from five different wheat varieties making the combination of CGE-on-a-chip analysis of one-step single-grain extraction in combination with automatic data evaluation a promising tool for fast wheat differentiation (within a day).

Fate of aflatoxin B(1) in contaminated corn gluten during acid hydrolysis.

BACKGROUND: Aflatoxins are a group of mycotoxins that cause serious chronic disease outbreaks and contaminate several food products such as corn and its by-product, corn gluten. The aim of the current study was to evaluate the effect of hydrochloric acid (HCl) on aflatoxin B(1) (AFB(1) ) degradation in contaminated corn gluten under different HCl concentrations, hydrolysis temperatures and hydrolysis times. RESULTS: During the wet milling process the highest AFB(1) level (45.68 µg kg(-1) ) (37.86%) was found in corn gluten fraction. Treatment with 1 mol L(-1) HCL at 110 °C resulted in degradation of AFB(1) by 27.6% (33.07 µg kg(-1) ) after 4 h and reached 42.5% (26.26 µg kg(-1) ) after 8 h. Increasing HCl concentration from 1 to 3 mol L(-1) HCl resulted in increased degradation of AFB(1) , while complete degradation occurred in the presence of 5 mol L(-1) HCl after 4 h at 110 °C. Meanwhile, half-life time of AFB(1) was recorded after 2 h at 100 °C and was < 2 h at 110 °C in the presence of 3 mol L(-1) HCl. CONCLUSION: It could be demonstrated that the manufacture of hydrolyzed vegetable protein is a suitable method for decontamination of aflatoxin in highly contaminated grains, especially gluten fractions. The hydrolysis reaction could be considered in terms of first-order reaction kinetics of AFB(1) degradation.

Partial characterization of proteins from baru (Dipteryx alata Vog) seeds.

BACKGROUND: Baru (Dipteryx alata Vog.) is a fruit distributed throughout the Brazilian savanna and contains a seed with a high protein content, whose properties have been rarely explored. The purpose of this study was to characterize this protein, especially by isolation and quantifying its fractions and measuring some of its molecular properties. RESULTS: Baru seeds contain 244 g kg(-1) protein on a dry weight basis. Solubility profiles showed a preponderance of globulins. This fraction dominated the seed composition, with 61.7 wt% of the total soluble proteins. Albumins and glutelins accounted for 14 and 3.3 wt%, respectively. SDS-PAGE resolution of albumin and globulin showed main bands with molecular weights of 84 kDa and 64, 66 and 73 kDa, respectively. The total protein of the flour and the globulin showed values of in vitro digestibility of 85.59% and 90.54%, relative to casein. Total globulin produced only one chromatographic peak, both on Sepharose CL-6B gel filtration and on DEAE-cellulose ion-exchange columns, eluted at a concentration of 0.12 mol L(-1) NaCl. CONCLUSION: The baru seed had high protein content with large quantities of storage proteins. The chromatographic and solubility profiles indicate the predominance of a fraction with characteristics of a legumin-type protein.