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At least 19 recordsLinked to original sources

PubMed1967

A determination of the sub-units of arachin by osmometry. Arachins A, B, and A1.

1. Osmotic pressure determinations of dissociated arachins are a particularly suitable method for determination of the number of sub-units in the protein, because they yield a number-average molecular weight. 2. Arachin, in 8m-urea-0.1m-sulphite, produces 12 sub-units from the form of molecular weight 345000. 3. When the urea concentration is varied the molecules became fully dissociated at 6m-urea-0.1m-sulphite. Although sulphite is necessary to break disulphide bridges, concentrations greater than 0.1m cause a re-aggregation of the sub-units. Similar results were obtained in guanidine solutions. 4. A new form of arachin has been discovered, A1, migrating more rapidly than arachin A. 5. The N-terminal residues of arachin have been re-investigated on more highly purified samples: they are glycine, valine and (iso)leucine in the proportions 4:1:1. 6. The three forms of arachin have the structure (B) beta(4)gammadelta, (A) alpha(2)beta(2)gammadelta and (A1) alpha(4)gammadelta, for the forms of molecular weight 170000. 7. Dissociation in 8m-urea produces some fragments, detected by gel electrophoresis, which appear to be dimers of the type alpha-S-S-beta, beta-S-S-beta, held together by disulphide bonds.

Amino Acids↗

PubMed1965

AN ELECTROPHORETIC INVESTIGATION OF GROUNDNUT PROTEINS: THE STRUCTURE OF ARACHINS A AND B.

1. The proteins of the groundnut cotyledon have been fractionated and analysed by DEAE-Sephadex chromatography and acrylamide-gel electrophoresis. Seventeen components were detected. 2. A new method is described for the preparation of arachin, using calcium precipitation. The product contains at least 99% of arachin. 3. The theory of acrylamide-gel electrophoresis is developed and applied to the arachin system to predict the molecular weight of one sub-unit of arachin. 4. A variant form of arachin, arachin B, has been discovered. Of 81 nuts, 27 contained only arachin B, 53 contained both arachin A and B, and one contained arachin A only. This is almost certainly a polymorphism of arachin; this is the first example of polymorphism to be reported in plant proteins. 5. A combination of controlled denaturation, electrophoretic analysis, ultracentrifuge and Sephadex filtration data has shown that arachin A contains four different kinds of peptide chains (alpha, beta, gamma and delta). Arachin B contains only beta, gamma and delta chains. 6. The most probable structure for arachin B, mol.wt. 330000 form, is 8 beta, 2 gamma and 2 delta chains, and for arachin A, 4 alpha, 4 beta, 2 gamma and 2 delta chains. Arachin without beta chains was not found. 7. The alpha and beta chains have mol.wts. of about 35000 and the gamma and delta chains of about 10000. 8. Three N-terminal groups were found: the alpha and beta chains both terminate in glycine; the gamma and delta chains terminate in isoleucine and glutamic acid. 9. Arachin contains no carbohydrate. 10. Disulphide bonds are not important in arachin: there are none between the alpha, beta, gamma and delta chains. 11. The amino acid compositions of arachins A and B are very similar. Glutamic acid and aspartic acid residues are exceptionally frequent.

Amino Acids↗

PubMedDate not supplied

Reversed-phase high-performance liquid chromatographic, gel electrophoretic and size exclusion chromatographic studies of subunit structure of arachin and its molecular species.

Arachin and its molecular species (arachin I and arachin II) were separated and isolated. The number and kind of subunits of arachin, arachin I and arachin II were determined. Studies were carried out under different experimental conditions using slab gel electrophoresis, size-exclusion chromatography and reversed-phase high-performance liquid chromatography. Gel electrophoresis was done under varying concentrations of resolving gel. Tube gel as well as slab gel electrophoresis were used and continuous as well as discontinuous buffer systems were used for both types of electrophoresis. In addition, the subunits were separated by reversed-phase HPLC using a gradient program. Arachin and arachin II were found to have 12 subunits each while arachin I showed six subunits. The subunits of arachin I were allowed to reconstitute by removing SDS. Eight combinations were tried for studying the reconstitution pattern. Molecular weight and weight ratio in each case were also determined.

Chromatography, Gel↗

PubMed1969

Immunochemical Studies on Arachis hypogaea Proteins With Particular Reference to the Reserve Proteins. I. Characterization, Distribution, and Properties of alpha-Arachin and alpha-Conarachin.

Fourteen antigenic constituents have been detected in Arachis hypogaea seeds. The major proteins of the classic arachin and conarachin fractions have been identified. Arachin contains 4 antigens (the major one called alpha-arachin) and conarachin contains 2 which have been called alpha(1), and alpha(2)-conarachin. Structural differences between alpha-arachin, alpha(1) and alpha(2)-conarachin are indicated by their different antigenic specificities. alpha-Arachin precipitates as a separate entity at low temperature. The action of trypsin on this protein induces an increase in electrophoretic mobility and prevents precipitation at low temperature. This enzyme has no detectable effect on alpha(1) and alpha(2)-conarachin.The proteins of the cotyledon and of the entire axis are quite similar in their immunoelectrophoretic patterns. However, quantitative and qualitative differences occur between the proteins found in the cotyledon and those of the 1-millimeter tip of the axis. In the latter, there is a 4-fold smaller proportion of alpha-arachin than in the cotyledon. Immunoelectrophoretic analysis of subcellular preparations from cotyledons confirms that alpha-arachin is an aleurin and that alpha(1)-conarachin is a typical cytoplasmic protein. Large and small aleurone grains appear very similar in their qualitative antigenic composition.

Journal Article↗

PubMed1975

Thermally induced permutations of antigenicity and conformation of arachin (peanut globular protein)*.

The reactivity of arachin (principal storage protein of the peanut) with anti-arachin decreased after arachin was heated at certain temperatures. Infrared and circular dichroic spectra of heated and unheated samples of arachin were examined to determine whether conformational modes changed concomitantly with decreased antigenicity. Infrared absorbances of each sample at amide I, II and V bands were essentially identical; however, absorbances at amide IV and VI bands were altered in relative intensities proportionally to the temperatures of treatment. Conformational modes, determined by circular dichroism, gradually increased in content of unordered structure from x-helical and pleated sheet modes relative to the temperature of treatment. These observations are discussed in regard to relationships of the loss of antigenicity to conformatonal changes in heated arachin.

Antigen-Antibody Reactions↗

PubMed1992

Effect of different proteolytic enzymes on the nature of subunit composition of arachins from groundnut (Arachis hypogaea L.).

Arachin, the major protein from groundnut, was isolated from three varieties of groundnut (Spanish Improved, TMV-2 and DH-3-30) using a modified procedure involving precipitation with 18% ammonium sulphate to obtain homogeneous protein. The homogeneity was judged by polyacrylamide gel electrophoresis, gel filtration and sedimentation velocity techniques as well as correlation with amino acid composition. Rates of hydrolysis of arachins by trypsin (pH 7.6) and alpha-chymotrypsin (pH 7.8) were significantly different between the three varieties. Arachin from the Spanish Improved variety contained higher amounts of alanine and phenylalanine and lower amounts of carbohydrate and phosphorus as compared to TMV-2 and DH-3-30. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis pattern of arachin from TMV-2 showed only seven bands of which the ones with low molecular weight were more intense than those of the other two varieties. The far-ultraviolet circular dichroic spectra showed no significant differences among the three varieties in respect of alpha-helix content (5 +/- 2%), beta-structure (19 +/- 2%) and the aperiodic structure. The observed differences in hydrolysis rates have been explained as due to the differences in the acidic and basic subunits of arachins.

Amino Acids↗

PubMed1989

Heat-induced reversible gelation of arachin: kinetics, thermodynamics and protein species involved in the process.

Arachin forms a heat-reversible gel under certain experimental conditions. The minimal gelling concentration for this system is 7.25%. Above minimal gelling concentration calculation of thermodynamic parameters for gelation of arachin revealed a constant delta Hbonding (-1220 cal.mol-1) where delta Sbonding values varied with an increase in protein concentration (ranging from -4.01 e.u. at 7.5% to -3.48 e.u. at 10.0%). The main steps involved in the gelation phenomenon include thermal denaturation of arachin, partial aggregation of heat-denatured protein molecules, setting of protein solution and maturation of the gel formed. Gel maturation process follows first order kinetics and is characterized by a large positive delta G+(+) (22,030 cal.mol-1). Determination of delta H+(+) and delta S+(+) for this process revealed that mostly delta S+(+) (-62.9 e.u.) contributes to the large positive delta G+(+), thus decreasing the overall rate of gel maturation process. This large negative delta S+(+) value probably arises from a loss of entropy of protein molecules because of their increased involvement in gel network formation. The polymer gel network seems to be primarily contributed by a part of both arachin dodecameric and hexameric species.

Arachis↗

PubMed1984

Acylated arachins. Physicochemical properties.

Acetylated and succinylated arachins were examined for various physico-chemical parameters such as viscosity, absorption and fluorescence spectra, gel electrophoretic patterns, gel filtration profiles and susceptibility to proteolysis. Acetylation and succinylation lead to dissociation of arachin into lower molecular weight fractions. The lower molecular weight fractions had a higher degree of succinylation compared to other fractions. The absorption and the fluorescence spectra were perturbed both by acetylation and by succinylation. Both fluorescence and viscosity data indicate denaturation of acylated arachins. The modified arachin was more susceptible to proteolysis by trypsin and chymotrypsin and varied in degree of hydrolysis.

Acylation↗

PubMed1980

Reversible gelation of arachin.

Arachin forms a gel at acidic pH (pH less than 3.8) which is thermolabile. The factors governing the gelation seem to be the concentration of the protein, heating temperature, heating interval, cooling temperature of the heated solution, pH, ionic strength and dielectric constant of the medium. Urea decreases gel strength. The cross-links involved in the gelatin of arachin seem to be noncovalent in nature.

Arachis↗

PubMed1996

The amino acid sequence and structural class of the arachin subunit of molecular weight 29, 100A.

Arachin subunit (mol. wt. 29,100) from peanut of variety G-201 was separated and isolated, its purity and homogeneity were ascertained. The subunit was cleaved with trypsin, chymotrypsin and Staphylococcus aureus V8 protease. The fragments obtained were separated and isolated by PAGE, gel filtration & ion exchange chromatography, these were subjected to amino acid analysis, and Edman degradation. The PTH amino acids obtained were identified by spectroscopy and TLC. The complete amino acid sequence of the subunit (226 residues) was established, and the structural class of arachin was predicted from the amino acid composition.

Amino Acid Sequence↗

PubMed1978

Effect of succinylation on the oligomeric structure of arachin.

Arachin succinylated to various levels has been studied by the techniques of sedimentation velocity, viscosity, absorption and fluorescence spectra, optical rotation and circular dichroism. Succinylation up to 60% leads to the dissociation of the parent 14S molecule to 9S and 4S fractions; above 60% succinylation, 4S fraction occurs predominantly. The other measured properties also show a gradual change up to 50% succinylation and a marked change above this level. The observed changes suggest that a new organised structure is formed before the 4S fraction is denatured.

Arachis↗

PubMed1982

Peroxide-induced conformational transitions of peanut storage protein (arachin).

Several effects of peroxides on protein have been described in the literature. Some of the effects have been ascribed to alterations in protein conformation but this has never been examined directly. This paper described responses of peanut storage globulin (arachin) to rancid oil and hydrogen peroxide as measured by electrophoretic mobility, antigenicity and circular dichroism of the globulin. Rancid oil and 3% hydrogen peroxide had little effect on these properties but 30% hydrogen peroxide increased the mobility, abolished the antigenicity and reduced the ordered structural modes of the protein. The results indicated that changes in protein conformation do not occur after contact with organoleptically rancid oil or dilute peroxides but do occur with concentrated peroxides.

Arachis↗

PubMed1990

Complete amino acid sequence of arachin subunit of molecular weight 21,000.

A subunit of molecular weight 21,000 from arachin, the major peanut protein, was isolated in pure form and primary structure was determined. The subunit was fragmented with CNBr, trypsin, and NBS; the fragments were separated and isolated by PAGE, gel filtration, Dowex treatment, and paper electrophoresis, and Edman degradation on each fragment, including the intact subunit, was performed. The PTH-amino acids thus obtained were identified by UV spectroscopy and TLC. The complete sequence of 176 residues was established by overlapping technique.

Amino Acid Sequence↗

PubMed1950