Soybean leaves, protein

SPILATRO, S.R., ANDERSON, J.M., Characterization of a soybean leaf protein that is related to the seed lectin and is increased with pod removal. Plant Physiol., 1989, 90, 1387-1393. 

Hepatitis B surface antigen (HBsAg) fused to soybean vegetative protein (VSPaS) Tobacco leaf VSPaS-HBsAg generated higher levels of serum IgG than native HBsAg in mice. 43... 

Less Conventional Sources of Protein. In addition (o the traditional animal sources of protein already described and the very large amounts of vegetable protein derived from the soybean, other sources of protein on a large scale for the future are under intense study. Among these are (1) oilseed crops, such as rapeseed and cottonseed (2) leaf proteins (3) algae and (4) single-cell protein. 

Guerra, D.J. and Ohlrogge, J.B. 1986. Partial purification and characterization of two forms of malonyl-coenzyme A-acyl carrier protein transacylase from soybean leaf tissue. Arch.BIochem.Biophys., 246 274-283. 

The reported (14) mechanisms of action of allelochemlcals Include effects on root ultrastructure and subsequent Inhibition of Ion absorption and water uptake, effects on hormone-induced growth, alteration of membrane permeability, changes In lipid and organic acid metabolism, inhibition of protein synthesis and alteration of enzyme activity, and effects on stomatal opening and on photosynthesis. Reduced leaf water potential Is one result of treatment with ferulic and p-coumaric acids (15). Colton and Einhellig (16) found that aqueous extracts of velvetleaf (Abutllon theophrastl Medic.) Increased diffusive resistance In soybean fGlycine max. (L.) Merr.] leaves, probably as a result of stomatal closure. In addition, there was evidence of water stress and reduced quantities of chlorophyll In Inhibited plants. 

In the quest to find other plants that are suitable as bioreactors, various monocoty-ledonous and dicotyledonous species have been tested. These include corn [16], rice and wheat [17], alfalfa [18], potato [19, 20], oilseed rape [21], pea [22], tomato [23] and soybean [24]. The major advantage of cereal crops is that recombinant proteins can be directed to accumulate in seeds, which are evolutionar specialized for storage and thus protect proteins from proteolytic degradation. Recombinant proteins are reported to remain stable in seeds for up to five months at room temperature [17] and for at least three years at refrigerator temperature without significant loss of activity [25]. In addition, the seed proteome is less complex than the leaf proteome, which makes purification quicker and more economical [26]. 

Seeds, leaf crops, and grasses are very efficient protein producers from the standpoint of amount per unit area. As indicated in Table IV, the more commonly used seeds and legumes, soybeans and wheat have relatively high protein production potentials (around 400 to 800 kg/ hectare). 

In plant leaves, nitrate reduction requires NADH produced by glycolytic activity (13), The ozone-induced depression of glycolytic metabolism in soybean leaves was also reflected in a depressed rate of nitrate reduction ( ), A single ozone exposure depressed the vivo nitrate reductase (NR) activity about 60% (Table III), To determine if ozone affected the NR protein directly, the in vitro NR activity was determined in leaf extracts from plants exposed to 0 and 980 pg/m ozone. 

Temperature-Dependence of Amino Acid Uptake in Soybean. The uptake of amino acids by plants into the soluble pool can be an energy-requiring process (52-54), as is the support of protein synthesis. We wished to show the temperature-dependence of influx of amino acids into soybean trifoliate leaf discs taken from control and ozonated seedlings in order to confirm this for the present system. Table II shows that amino acid influx during 30 min was reduced by the lowered temperature by about 70%, and protein synthesis by about 85%, when labelling of control discs proceeded at ice bath temperatures. Qualitatively similar reductions occurred in discs taken from ozonated (50 5 pphm,... 

Table IV shows typical results of the pool overloading experiments in the soybean trifoliate leaf. Visible damage to ozonated plants after 24 hr incubation was, as usual, taken as necessary for an experiment to be valid. Clearly, incorporation of label into protein was reduced where casein hydrolysate had been used in control and treated discs to overload the soluble pools. Just as clearly, total counts present in the soluble pool of treated tissue were reduced by ozonation whatever the after-treatment. The reduction of label in the soluble pool in control and ozonated discs due to casein treatment was approximately 30% in each case the reduction of label incorporation due to ozone was about 36% in the case of water treatment and about 14% in the case of casein treatment.

We conclude that by 3 3/4 hr after the onset of ozonation the inhibition of protein synthesis has become a factor in the overall physiological disturbance in the soybean trifoliate leaf. However, this was not necessarily the case for the earlier (55-100 min) events described in Figure 6. That data showed that protein synthesis was depressed by as little as 15 min of ozone exposure, but not depressed further as ozone exposure was lengthened to 90 min. What we have been unable to show by the overloading experiment is the exclusivity, immediately following ozonation for brief periods, of the inhibition of amino acid... 

The best method for evaluation of the color problem is to prepare a food product containing the protein flour. Biscuits were routinely used as the model food system. Figure 5 illustrates the color of biscuits prepared with lOOZ wheat flour and with 20Z plant-protein products. The color of the biscuits prepared with soybean and peanut flours shows that these ingredients do not cause a serious color problem. However, sunflower, alfalfa leaf, and cottonseed flours do produce a discoloration in this model food system. The L and b values generally reflect this visual evaluation. 

Jacobsen, K., Laursen, N.B., Jensen, E.O., Marker, A., Poulson, C. Marcker, K.A. (1990). HMG-like proteins from leaf and nodule nuclei interact with different AT motifs in soybean nodule promoters. The Plant Cell 2, 85-94. 

Fig. 1. CAT activities in seeds of transgenic tobacco plants containing hs promoter-CAT constructs. A, Schematic structure of chimaeric genes introduced into tobacco. Details of the construction are described by Schoffl et al. (1989,1991). HSE sequences with the consensus C-GAA-TTC-G are symbolised by boxes the synthetic HSE2 is represented by two overlapping soybean HSEs. The CaMV promoter is a truncated silent version of the 35S promoter, providing only the TATA box and the transcription start site. B, CAT assays were performed as described by Schoffl et al. (1989), using 50 pg protein from seed extracts and 10 jig from leaf extracts. Dry seeds (ds) without imbibition and 20 h imbibed seeds (is), derived from the same plant, were used. Heat treatment (hs) was carried out for 2h at 40 °C prior to protein extraction. Control extracts (c) were prepared from leaves incubated at 25 °C. cm, WC-chloramphenicol acm, acetylated form of cm.

Kulaeva et al. (29) have demonstrated modified gene expression in leaf tissue after administration of BR, with several new proteins being induced, and evidence for concentration effects. Also, Clouse et al (30) have reported new polypeptides, and up and down regulation in auxin-sensitive soybean stem segments treated with BR. 

The only other plant enzyme which has been reported to be stimulated by the same three treatments is isofloridoside-phosphate synthase (4) as previously described. Those authors presented evidence for the presence of an endogenous acid protease which could stimulate the enzyme. They also proposed (4) that calmodulin and protein kinase somehow stimulated this protease which in turn proteolytically-activated the isofloridoside-phosphate synthase. Such a mechanism is also conceivable for the potato leaf phospholipase. The only other plant enzyme which has been reported to be stimulated by proteolytic activation is a glucan synthase in soybean cells (6). It is also interesting to note that an animal phospholipase, pancreatic phospholipase A, is activated by the proteolytic removal of a heptapeptide from the ammo terminus (7). 

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. 

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