Germinating castor beans

More recently the properties of plant FDPases have been reinvestigated by Scala et al. (100). Three activities were separated from ungerminated and germinating castor beans and from mature leaves, which were similar in molecular weight (120,000-135,000) but which... 

The neutral and nonspecific FDPases may function in nonphotosynthetic carbohydrate metabolism in higher plants. In the germinating castor bean acetate is utilized for the synthesis of sucrose 107, 108), and the presence of the AMP-sensitive FDPase in plant embryo tissues has been demonstrated by Bianchetti and Satirana 109). The changes in levels of this enzyme in response to changes in physiological conditions 109) support a gluconeogenic role for this enzyme. The role of the nonspecific acid FDPase in plant tissues remains unknown. 

Goldner, W., and Beevers, H. 1989. Starch synthase and starch branching enzyme from germinating castor bean endosperm. Phytochemistry 28, 1809-1812. 

Beef brain, heart, and liver have been the most frequently used sources of purified phospholipid transfer proteins. From these tissues, three classes of transfer proteins have been identified a phosphatidylcholine-specific transfer protein, a phosphatidylinositol-specific transfer protein, and a nonspecific transfer protein. In addition to the purified proteins shown in Table I, other transfer proteins have been partially purified from a wide variety of tissues and organisms including rat intestine (Lutton and Zilversmit, 1976a), rat lung (Van Golde et al., 1980), sheep lung (Robinson et al., 1978), beef spleen (Metz and Radin, 1982), potato tubers (Kader, 1975), endosperm of germinating castor bean (Douady et al., 1980), Rhodopseudomonas sphaeroides (Cohen et al., 1979), and yeast (Cobon et al., 1976). 

Plaxton, W.C. Purification of pyruvate kinase from germinating castor bean endosperm. Plant Physiol., 86, 1064-1069 (1988)... 

Kombrink, E. Kruger, N.J. Inhibition by metabolic intermediates of pyro-phosphate D-fructose 6-phosphate phosphotransferase from germinating castor bean endosperm. Z. Pflanzenphysiol., 114, 443-453 (1984)... 

After infiltration of L-[U- C]valine into cotyledons of germinating castor bean, there was no [ CJOa produced after 12 h (Stewart and Beevers, 1%7). A small incorporation of label into sugars and organic acids was found. 

A prenyl transferase, FPP-synthetase (EC 2.5.1.1), from extracts of germinating castor bean seedlings, has been highly purified both forms obtained synthesized all -fame-syl pyrophosphate (Porter and Spurgeon, 1981). FPP synthetases also have been demonstrated from Gossypium hirsutum and from Pisum sativum (Croteau and Johnson, 1985). E,E-Famesyl pyrophosphate synthetase is proposed to employ a stepwise ionization-condensation mechanism involving a rigid pyrophosphate-carbonium ion pair as an intermediate (Poulter et al., 1981). 

The famesyl transferase of germinating castor bean Ri-cinus communis, Euphorbiaceae) seeds occurs in small quan-... 

However, generalization to include other oil seeds is not indicated, because lipases in other organelles must be involved in gluconeogenesis (see below). Involvement of the acid lipase in gluconeogenesis of castor bean has not been proven, and Muto and Bee vers (1974) have pointed out that the enzyme activity decreases before the peak of lipid breakdown in germinating castor beans. 

Fig. 6. Proposed pathway for complete degradation of ricinoleic acid in germinating castor beans (adapted from Hutton and Stumpf, 1971). /3-Oxidation steps liberate Q units as acetyl-CoA. Reproduced from Galliard (1975).

In addition Vick and Beevers (1978) isolated proplastids from endosperm of germinating castor beans and demonstrated that these organelles were sites of fatty acid synthesis. Kleinig and Liedvogel (1978) have obtained chromoplasts from daffodO petals and have demonstrated extensive incorporation of [ C]acetate into palmitic acid. Nothelfer ei al. (1977) have also shown in soybean tissue culture suspension cells that proplastids are capable of synthesizing fatty acids. 

Different Fatty Acid Compositions of Embryo and Endosperm from Germinating Castor Bean Seeds"... 

Interesting results were obtained recently on new plant tissues. Intensive work from Beevers group (Moore et al., 1973 Moore, 1975 Lord, 1976 Vick and Beevers, 1977) had confirmed that the endoplasmic reticulum was the site of phospholipid synthesis in endosperms of germinated castor bean seeds. Although phosphatidylcholine and phosphatidylethanolamine are abundant in castor bean mitochondria (Ohmori and Yamada, 1974), these organelles do not contain the enzymes responsible for the syntheses of these... 

Endosperm halves were collected, homogenized, fractionated and enzymes assayed at selected times following germination of castor beans in moist vermiculite in the dark at 30°C. For the ethanolamine kinase (EK) assay the reaction mixture contained in a final volume of 50 i 100 mM Tris-HCl (pH8.3), 5 mM ATP, 10 mM MgCb, 563 [iM [2- C]ethanolamine. The reaction was carried out at 37" C for 1 h, terminated with 80 al of 60% trichloroacetic acid, and phosphoethanolamine separated from ethanolamine by ascending paper chromatography. Ethanolamine-phosphate cytidylyltransferase (ECT) was prepared from germinated castor bean endosperm and assayed as described by... 

Stewart C R, Beevers H 1967 Gluconeogenesis from amino acids in germinating castor bean endosperm and its role in transport to the embryo. Plant Physiol 42 1587-1595... 

Takishima, K., Watanabe, S., Yamada, M. and Mamlya, G., 1986 -The amino acid sequence of the nonspecific lipid transfer protein from germinated castor bean endosperm.Biochim. Biophys. Acta 870, 248-250. 

Tanaka T. and Yamada M., 1982 - Properties of phospholipid exchange proteins from germinated castor bean endosperms in Biochemistry and Metabolism of Plant Lipids, J.F.G.M. and P.J.C.Kulper Eds, Elsevier, p. 99-106. 

Yamada M., Tanaka T., Kader J.C. and Mazliak P. (1978) - Transfer of phospholipids from microsomes to mitochondria in germinating castor bean endosperm. Plant Cell Physiol., 173-176. 

ISOFORMS OF NON-SPECIFIC LIPID TRANSFER PROTEIN FROM GERMINATED CASTOR BEAN SEEDS... 

A non specific lipid transfer protein (ns-LTP) which enhances the transfer of both phospholipids and galactolipids between biomembranes has been purified from germinated castor bean seeds (Watanabe 1906) and its primary structure has been determined to be 9.3 KD-protein with 92 amino acid residues (Takishima 1986). We now call this nsLTP-9A, because isoforms of nsLTP-9A have been found in the same materials. This paper represents the occurrence of ns-LTP isoforms in germinated castor bean tissues. Materials and Methods... 

Fig,l. Immunoblotting pattern of germinated castor bean tissues by anti-ns-LTP-9A serum. 

The ammo-acid seguence of the non-specific lipid transfer protein from germinated castor bean endosperms Biochem. Biophys. Acta 070,248-255. 

XXXVII. Characterization of the 8-oxidation system from maturing and germinating castor bean seeds. Plant Physiol. 44 508 (1969). 

The pathway of ricinoleic acid catabolism in the germinating castor bean (Ricinus communis L.) and pea (Pisum sativum L.). Arch. Biochem. Biophys. 142 48 (1971). 

Fig. 1. The amino acid sequence of the non-specific LTP from germinated castor bean seeds. The solid lines indicate the sequenced part, whereas the broken lines indicate those part of the fragments in which the amino acid residues were not identified. S, Staphylococci aureus protease peptide Sl-B and Sl-C, chymotryptic peptides...

Fig. 3 ghows predicted conformational profiles of PC-specific LTP from bovine liver and non-specific LTP from germinated castor bean seeds according to Chou and Fasman. The repeated pattern of g-structure in the latter region of the amino acid sequence is characteristic of bovine liver LTP, whereas there is no repeated g-structure in the latter region of castor bean LTP. This suggests difference in the interaction of the protein with the lipid between specific and non-specific LTPs, and therefore, difference in transport mechanism between both types of LTPs. 

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