Physicochemical Studies on the Proteins of the Peanut Cotyledon and Embryonic Axis

Abstract

Subcellular fractions fronm the cotyledon obtained bv differential aind density gradient centrifugation, and extracts of total proteins from botlh cotyledon and axial tissues were analyzed by diethvlaminoethyl cellulose clironiatography, zone electrophoresis, ultracentrifugatioti, immunodiffusion, and immunoelectrophoresis. Fractionation and characterization of proteinis in subcellular organelles of the peanut reaffirin that a-arachin is located in the protein bodies of the cells. Results obtained bv diethlv-laminoetlhyl cellulose chromatograplhy of subeelltular fractions suggest that soine of the conaraclhin proteins are cytoplasmic. am-Conarachin is cv toplasmic, and a2-conarachin is particle-botund. a-Arachiii and a2-conarachin predonminate in the cotyledon. Quantitative differences for other proteins were also observed. Althlotuglh qualitative similarities are apparent by iimuiitnoelectroplhoresis, nmajor differences were observed in tde sedimiientation patterns, zone electroplioreograms, antd ill the dietlhvlaminoethvl cellulose chromatograms of total proteini extracts fromn the cotyledon and the axis.The major proteins of the peanut cotyledon have been characterized as albumins and globulins. The globulins, considered primarily as the reserve or storage proteins of the seed, were first classified by Johns and Jones (10) and by Jones and Horn (14) according to their solubility in ammonium sulfate. The two classic globulin fractions, arachin and conarachin, have been studied extensively by several investigators (4, 5, 11-13). They exist as complex systems with sedimentation and electrophoretic patterns which change considerably, depending upon the experimental conditions employed. The major proteins of classic arachin and conarachin have been named a-arachin and a-conarachin. Although homogenous by zone electrophoresis and sedimentation analysis, immunoelectrophoresis has shown that arachin contains four proteins (a-arachin being the major component) and a-conarachin contains two components called al-and a2-conarachin (5, 6). Preparation of Protein Extracts. Two grams of each tissue were homogenized in a Sorvall Omni-Mixer' in 8 ml of phosphate buffer, pH 7.9, ionic strength 0.2 (0.008 M NaH2PO4 -H20 0.64 M Na2HPO4) at 5 C. The homogenate was strained through four layers of cheesecloth, and the filtrate was clarified by centrifugation at 37,000g for 30 min in a Sorvall RC-2 centrifuge at 20 C. The final supernatant was dialyzed against phosphate buffer, pH 7.9, ionic strength 0.03 for 24 hr at 5 C. After warming to room temperature (25 C), the extracts were recentrifuged at 37,000g for 30 min to yield slightly turbid supernatants. These extracts and those from subcellular fractions were employed in the following investigations.

Effect of heat on peanut proteins. I. Solubility properties and immunochemical-electrophoretic modifications

“…The two bands corresponding to a-arachin have slightly different mobilities but show a continuous precipitin arc. These two zones were separated by starch gel electrophoresis and were shown to be antigenically identical by double diffusion (Neucere, 1971). a2-Conarachin remains at the interface of the stacking gel and the running gel.…”

Quantitative Ultrastructure and Protein Composition of Date Palm (Phoenix Dactylifera) Seeds: A Comparative Study of Endosperm vs. Embryo

“…Differences in proteins between different parts of a seed have been documented for soybean (Alekseeva and Kovarskaya, 1978;Knypl and Radziwonowska, 1979;Meinke, Chen, and Beachy, 1981), castor bean (Sobolev and Dmitrieva, 1983;Kermode et al, 1985), mung bean (Manikam and Carlier, 1980), and peanut (Neucere and Ory, 1970). In soybean, the buffer extractable proteins of the cotyledons, unlike those ofthe embryo axis, contain the 11S acidic and basic glycinin components, whereas a 24 kD protein of unknown function is specific to the axis (Meinke et al, 1981).…”

“…In castor bean, certain glycoproteins and lectins, RCA 1 and ricin, occur only in the endosperm. Neucere and Ory (1970) believe that proteins of the embryonic axis are immunologically different from those of the cotyledons in peanut.…”

Gel electrophoretic analysis of peanut proteins and enzymes. I. Characterization of DEAE-cellulose separated fractions

“…There have been many investigations on the reserve proteins of peanuts because of their potential usefulness as food supplements. In general, these studies have shown that most of the proteins are easily extractable (Altschul et al, 1961(Altschul et al, , 1964aDawson, 1971; Dechary and Altschul, 1966;Dechary et al, 1961) and can be separated into two major fractions, arachin and conarachin (Daussant et al, 1969a,b;Dechary et al, 1961; Evans et al, 1962;Neucere, 1969; Neucere and Ory, 1970). More extensive purification of these two fractions (Dawson, 1971;Evans et al, 1962;Tombs, 1965;Tombs and Lowe, 1967;Neucere, 1969) has revealed that they are composed of complex large molecular weight globulins (a-arachin, a-conarachin), plus some other closely related components, not completely separated by the usual techniques.…”