Partial characterization of an allergenic glycoprotein from peanut (Arachis hypogaea L.).

A concanavalin A-reactive glycoprotein allergen has been isolated from peanut (Arachis hypogaea). The allergen was separated by affinity chromatography and purified by gel permeation and ion-exchange chromatography. The monomeric molecular weight is 65,000 and the pI is 4.6. The presence of one cysteine residue per molecule results in some dimer formation. Concanavalin A-reactive glycoprotein is a potent allergen for peanut-sensitive patients in both in vivo and in vitro tests. It is allergenically stable, on in vitro examination, at temperatures of up to 100 degrees C and over the pH range 2.8-10. Removal of the carbohydrate moiety failed to eliminate the allergenicity. Concanavalin A-reactive glycoprotein is identified in the crossed immunoelectrophoretic pattern as a major antigen of peanut protein extract but its structural characteristics indicate that it is probably not a component of the major storage-protein complex, arachin.

Lectins in the United States diet: a survey of lectins in commonly consumed foods and a review of the literature.

Plant lectins or phytohemagglutinins possess potent in vivo biological activities. Some, primarily of the family Leguminosae, have been shown to have deleterious nutritional effects. Little information exists, however, regarding the prevalence of lectins or the specific foods that contain lectins in the United States diet. In the present study the edible parts of 29 of 88 foods tested, including common salad ingredients, fresh fruits, roasted nuts, and processed cereals were found to possess significant lectin-like activity as assessed by hemagglutination and bacterial agglutination assays. Based on this survey and a review of the literature we conclude that dietary exposure to plant lectins is widespread. The spectrum of nutritional consequences of such exposure remains to be determined.

Amino acid sequences of trypsin-chymotrypsin inhibitors (A-I, A-II, B-I, and B-II) from peanut (Arachis hypogaea): a discussion on the molecular evolution of legume Bowman-Birk type inhibitors.

The amino acid sequences of four peanut protease inhibitors (A-I, A-II, B-I, and B-II) were determined by conventional methods and by comparison of peptide maps of their tryptic digests with that of B-III on HPLC. A-I, A-II, B-I, and B-III had the same amino acid sequence except for differences in their N-terminal regions. This suggests that the four inhibitors would be derived from an original inhibitor with a longer N-terminal amino acid sequence by proteolysis of its N-terminal region. But B-II possessed an extremely different amino acid sequence from those of the other peanut inhibitors and was thought to be biosynthesized from a gene different from that of the other inhibitors. A phylogenetic tree of legume double-headed inhibitors was constructed on the basis of the matrix of amino acid differences among their sequences. The double-headed inhibitors whose sequences have been determined were classified into four groups.

The structure of Bowman-Birk type protease inhibitor A-II from peanut (Arachis hypogaea) at 3.3 A resolution.

The structure of Bowman-Birk type protease inhibitor (A-II from peanut) is described at 3.3 A resolution. The molecules form a tetramer with 222 local symmetry in our crystals. Each monomer has an elongated shape with approximate dimensions of 45 X 15 X 15 A and consists of two distinct domains. The three-dimensional structures of the two domains are similar and are related by the intramolecular approximate twofold rotation axis. The two independent protease binding sites protrude from the molecular body on opposite sides. A scheme for the molecular evolution of the double-headed Bowman-Birk type protease inhibitors is proposed, based on the three-dimensional structure.

Purification and characterization of protease inhibitors from peanuts (Arachis hypogaea).

Five protease inhibitors were isolated from peanut seeds and named A-I, A-II, B-I, B-II, and B-III. These inhibitors seemed to be Bowman-Birk type inhibitors judging from their low molecular weights and high cystine contents. All the inhibitors inhibited both bovine trypsin and chymotrypsin at ratios of 1:2 and 1:1, respectively, but not simultaneously. The complexes of the inhibitors and trypsin no longer inhibit chymotrypsin. On the other hand, their complexes with chymotrypsin inhibit trypsin with a slow release of chymotrypsin.

Lectin expression in neoplastic and non-neoplastic lesions of the rectum.

The expression of six lectins (Arachis hypogaea, B. simplicifolia I, concanavalin A, Dolichus biflorus, Triticum vulgaris, Lotus tetragonolobus) was studied in 24 adenocarcinomas, 24 adenomas, 20 metaplastic polyps, 17 specimens of mucosal prolapse (solitary ulcer syndrome) and 10 of normal mucosa, all taken from the rectum. Qualitative, quantitative and distributive differences in lectin expression were observed between adenocarcinoma and normal mucosa. These cancer-associated glycoprotein alterations were also observed, though to a lesser extent, in benign neoplastic and non-neoplastic lesions of the rectum. It appears therefore that the glycoprotein modifications associated with malignant transformation are not specific indicators of malignancy. It is suggested that the common denominator is a disturbance in the activities of enzymes, particularly the glycosyl-transferases and glycosidases, involved in the biosynthesis of glycoprotein. This disturbance can occur in situations where cells are less differentiated either through developmental immaturity, rapid cellular division or neoplastic de-differentiation. These changes are therefore more likely to reflect the state of differentiation rather than the malignant nature of the cells. It is shown that the greater the deviation of the lesion from normal the greater the glycoprotein alterations. The potential usefulness of lectin expressions as predictive indicators of biological behaviour of adenocarcinomas of the large bowel needs further studies.

Comprehensive evaluation of fatty acids in foods. IV. Nuts, peanuts, and soups.

As part of USDA research to provide reliable and up-to-date tabulations of lipids and fatty acids in foods, representative values have been derived and tabulated for nuts and commercially canned condensed soups. Except for palm-type nuts, unsaturated fatty acids are the major acids in nuts; oleic acid is generally the predominant unsaturated fatty acid. The new fatty acid values indicate greater concentrations of saturated fatty acids than previously reported. The P:S ratios for nuts and peanuts are presented. The fatty acid contents of soups are varied and reflect the lipid composition of the source(s) of fat of the particular ingredients used in the manufacture of these products. These new values for fatty acids in nuts and soups should greatly help nutritionists and dietitians to better assess the total contribution of each particular fatty acid to the diet.

Acylglycerol structure of peanut oils of different atherogenic potential.

Detailed investigation was made of the triacylglycerol structure of native, simulated, and interesterified peanut oils, which had previously been shown to differ markedly in their atherogenic potential. By means of chromatographic and stereospecific analyses, it was shown that the more atherogenic native oil contains a significantly greater proportion of triacylglycerols with linoleic in sn-2-position and arachidic, behenic, and lignoceric acids in sn-3-position that the synthetic oils. It is suggested that the atherogenicity may arise from a relative metabolic unavailability of the linoleic acid from the native oil, which may be due in part to the presence of long chain saturated acids in the outer position. This might render the oil metabolically more saturated that the interesterified oils of the same total fatty acid composition, which contain a much greater proportion of the linoleic acid in the primary postions of the triacylglycerol molecule. The identification of specific triacylglycerols may allow the experimental testing of this hypothesis by feeding synthetic triacylglycerols incorporating the potentially atherogenic features.

Peanut alkaline lipase.

Peanut alkaline lipase, (glycerol ester hydrolase EC 3.1.1.3), pH optimum 8.5, was isolated from acetone powders prepared from developing and germinated peanut seed (arachis hypogaea L. var. NC-2). Enzyme activity/seed increased in successive developmental stages. The course of the hydrolytic reaction was linear with regard to enzyme concentration and all times tested up to periods exceeding 60 min. Km for the reaction was determined to be 2.6 times 10-4M. Molecular weight of peanut lipase, as estimated by Sephadex gel filtration and sodium dodecyl sulfate gel electrophoresis, was ca. 55,000.

Inhibition of chemically-induced skin carcinogenesis in mice by peanut oil preparations.

Epidermal hyperplasia and sebaceous gland destruction - good indicators of carcinogenic potential - were studied in short-term mouse skin experiments following application of BaP and TPA dissolved either in a peanut oil mixture or in acetone. Subsequently, the carcinogenicity of BaP and DMBA alone or in association with TPA was dissolved in the same vehicles, and determined in mouse long-term skin tests. In parallel, ODC activity and binding to DNA, RNA and proteins were examined in epidermal cells after exposure to TPA and BaP respectively. When the peanut oil excipient was used as a solvent, a complete inhibition of BaP and TPA activities was observed in short-term skin tests, as well as a complete inhibition of BaP, DMBA and TPA carcinogenicity in long-term tests. TPA-induced ODC activity was suppressed by the peanut oil mixture while BaP binding to nucleic acids and proteins of epidermal cells was only slightly inhibited. These results indicate that the excipient possesses anti-carcinogenic potentials for epidermal cells. The persistence of BaP binding to macromolecules in epidermal cells without tumor development suggests that the carcinogenic action of BaP may include both genotoxic and epigenetic mechanisms.

Determination of aflatoxins in peanut products using reverse phase HPLC.

A high performance liquid chromatographic (HPLC) method is described for the determination of the four major aflatoxins, B1, B2, G1 and G2, in peanut products. The aflatoxins are extracted by adapting a procedure developed by Pons (1) at the SRRC, USDA, and quantitated utilizing a new 5 mum reverse-phase column with NaCl/acetontrile/methanol mobile phase (3 + 1 + 1). The 5 mum column achieved baseline resolution of each of the four aflatoxins. Retention times and peak heights were reproducible. The procedure was successfully applied to several types of peanut products and was applicable to both roasted and unroasted peanuts, which is a decided advantage over the current CB and BF extraction methods. Additionally, it can be used for sweetened peanut matrixes with no interferences in the chromatography. The total time required for sample preparation and aflatoxin determination is less than 1.5 hours.

Aflatoxin and liver cancer in Karachi, a preliminary survey.

A cause and effect relationship of Aflatoxin and liver cancer is well established. The incidence of liver cancer is 3.6% in Karachi (Zuberi et al., 1976) and Aflatoxins have been detected in 43% of 28 samples of food analysed in this study. The long term ingestion of aflatoxin with food may have some effect on the existing pattern of liver cancer in Karachi.