Spinach leaf extract

FIGURE 7.2 Kubelka-Munk densitogram of a spinach leaf extract taken at 305 nm. The two peaks at 16-mm and 17-mm distances are due to chlorophyll b and chlorophyll a. 

CA activities in crude spinach leaf extract was determinated with pH--meter system. 

Kates (1955) extended the research of earlier workers on the degradation of PC by plant extracts. The action of phospholipase D was readily measured by the release of choline, but the release of water-soluble organic phosphate and inorganic phosphate was also measured. Spinach leaf extracts were particularly effective in releasing inorganic phosphate. A 15,(XK)-g particulate fraction of leaf homogenate was used for the assay. The pH optimum for phosphate release was 5 it was pointed out that this may reflect the pH optimum for the release of PA, that is, the action of phospholipase D. 

P-enolpyruvate carboxylase was first observed and measured in spinach leaf extracts by Bandurski and Greiner (1953), and was quickly shown to be an important carboxylating enzyme in succulent plants (e.g.. Walker, 1957). Since its discovery and implication in Crassulacean Acid Metabolism, it has been studied... 

An extract from the soluble stromal proteins of purified and intact spinach-leaf chloroplasts was prepared by lysis of the cells in buffer, centrifugation of the suspension of broken cells, and concentration of the supernatant with removal of insoluble material. This extract contained all of the enzymes involved in the condensation of the cyclic moieties of thiamine, thiazole, and pyramine. Thus, the synthesis of thiamine in this extract following the addition of pyramine and putative precursors was a proof that the system had the possibility of building the thiazole. It was found that L-tyrosine was the donor of the C-2 carbon atom of thiazole, as in E. coli. Also, as in E. coli cells, addition of 1 -deoxy-D-f/irco-pen-tulose permitted synthesis of the thiamine structure. The relevant enzymes were localized by gel filtration in a fraction covering the 50- to 350-kDa molecular-mass range. This fraction was able to catalyze the formation of the thiazole moiety of thiamine from 0.1 -mM 1-deoxy-D-t/ireo-pentulose at the rate of 220 pmol per mg of protein per hour, in the presence of ATP and Mg2+. 

Uchiyama et al. [36] used cucumber juice (source of ascorbate oxidase) for the first time as carrier in a flow injection system for the determination of L-ascorbic acid. In another work, the same researchers used banana pulp and spinach leaf solution as a source of polyphenol oxidase (PPO) in a flow injection system for the determination of polyphenols [37]. However, the first biosensor based on vegetable crude extract (homogenate) was constructed by Signori and Fatibello-Filho [38]. In this study, an amperometric biosensor for the determination of phenols was proposed using a crude extract of yam (Alocasia macrohiza)... 

Work with a variety of plant systems has shown that multiple forms of SSS are present. Studies on barley endosperm, pea seeds, wheat endosperm, sorghum seeds, teosinte seeds, spinach leaf, maize endosperm, potato tuber, and rice seed extracts have indicated the presence of at least two major forms of SSS (reviewed in Preiss and Levi, 1980 Preiss, 1988 Preiss and Sivak, 1996), designated as types I and II. In maize leaf (Dang and Boyer, 1988) and castor bean endosperm (Goldner and Beevers, 1989), only one form of starch synthase was found, but since no extensive purification was attempted, the possibility remained that existing multiforms were not separated. Indeed, Downton and Hawker (1973) did find two forms of starch synthase in maize leaf, and thus the issue of the number of forms... 

Fig. 6. (A) Effect of composition of a binary soivent mixture on the apparent Chi a Aotal chlorophyli moiar ratio in extracts of spinach leaf tissue (0) and chloroplasts ( ). (B) relationship between the Chi a/Chl a molar ratio and the Chi a/P700 molar ratio for a number of P700-enriched subchloroplast particles by chloroform extraction (o) and by acetone extraction ( ). The solid line ciosest to the open circles is for Chi aVP700=1 and that nearest the filled circles for Chi aVP700= 2. See text for details. Figure source (A) Watanabe, Kobayashi, Maeda, Oba, Yoshida, Van de Meent and Amesz (1992) Function of the C13 -epimer chlorophylls in type I photosystem reaction centers. In N Murata (ed) Research In Photosynthesis, Vol III 4. Kluwer Acad PubI (B) Maeda, Watanabe, Kobayashi and Ikegami (1992) Presence of two chlorophyll a molecules at the core of photosystem I. Biochim Biophys Acta 1099 78.

Extractant Spinach leaf Synechocystis particles highly enriched in P700 ... 

Apocynin and spinach leaf antioxidant extract Grape seed proanthocyanidin extract... 

The transamination of the a-amino group to a keto acid acceptor (reaction 2) has been demonstrated in a number of higher plant studies (Nahler and Ruis, 1973 Streeter, 1977 Lloyd and Joy, 1978). The product of the transamination is 2-oxosuccinamate. This can be deamidated to oxaloacetate by lettuce and spinach leaf preparations (Meister, 1953). A similar reaction was reported by Streeter (1977) in soybean and pea leaf extracts. On the other hand, Joy (1978) reported that the 2-oxosuccinamate is reduced to 2-hydroxysuccinamate in these leaves in vivo. The apparent discrepancy between the results of Streeter (1977) and those of Joy (1978) may be due to the enzyme assay used by the former. It consisted of the oxidation of NADH in the presence of the enzyme extract and 2-oxosuccinamate. The assumption was that deamidation occurred leading to oxaloacetate which then acted as the substrate of endogenous malate dehydrogenase. The work of Davies (1961) showed that plant malate dehydrogenase is not specific for oxaloacetate, and it is possible that the 2-oxosuccinamate may act as a substrate. Meister (1953). actually measured the production of ammonia from 2-oxosuccinamate by his leaf preparations. 

The rate of light induction of thioredoxin synthesis was determined by experiments of in vivo synthesis wit spinach seedlings leaf-supplied under illumination with a pulse of S-methionine. Leaf extracts showed by immunoprecipitation with a specific antiserum raised against spinach thioredoxin /, a labelled polypeptide of about 12 kDa m.w. coemigrating in SDS-electrophoresis with spinach thioredoxin /. The amount of labelled protein increases in first 20 h after labelling, and... 

Fig. 6 Nitrate reductase activity (NRA) in crude leaf extracts (desalted) from spinach leaves which were exposed either to air or COp-free air, as indieated (arrows). Extraction or assay buffer contained either MgCl, (5mM) or EDTA (5mM).

Rosenberg, L.L., Capindale,J.B., Whatley, F.R. Formation of oxaloacetate and aspartate from phosphoenol-pyruvate in spinach leaf chloroplast extract. Nature (London) 181, 632-633 (1958)... 

Pol3mudeotide phosphoiylase has been found in a number of microorganisms 208) and has been purified from extracts of Azotobacter vinelandii 196), E. cM 199), Micrococcus lysodeikticus 197,209), AlcdUgenes faecalis K)8), and yeast 209). It has also been foimd in extracts of spinach leaf 208) and in guinea pig liver nuclei 210). 

Several different plant species (i.e. spinach, pea, soybean, corn, wheat, and rye) were initially screened for ACS activity. Leaves (5 g) were homogenized, centrifuged at 17300 and the supernatant desalted on a Sephadex G-25 column. From the desalted leaf extracts ACS was found to be highest in spinach (7.7 units/mg protein) followed by peas (4.01 units/mg protein) and corn (3.79 units/mg protein). Rye, soybeans. 

Added to extracts of mustard greens, celery, head lettuce, leaf lettuce, spinach, and tobacco only. 

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