Protein body

Sub-cellular bodies consisting of protein were first isolated from certain oil seeds by Hartig in 1855 [34]. He called these protein bodies aleurone grains 

Various hydrolases are in fact associated with the protein bodies, though we should realize that some of the enzymes may be contaminants from the cytoplasm. Acid proteinases have been found in protein bodies of Gossypium [47, 79], V faba [54], Hordeum [55] and Cannabis [66]. In the last, the proteinase is active against the crystalloid moiety (edestin) and has, therefore, been called edestinase [66]. The occurrence of these various enzymes for the hydrolysis of the native protein therefore suggests the possible lysosomal nature of protein bodies. 

The characteristics of the protein bodies may vary even in one seed and their distribution can also be unequal. In Yucca, protein bodies of the perisperm (the major storage tissue) have a different ultrastructure from those in the 

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Fig. 1. Transmission electron micrograph of a section of a mature, hydrated soybean cotyledon. Protein bodies (PB), lipid bodies (LB), and cell wall (CW)...

Seeds. The seeds are produced in pods containing two or three seeds. The kernels are almost spherical to roughly cylindrical (0.4—1.1 g each) and consist of a thin coat (testa) containing two cotyledons and the embryo. Cotyledons contain protein bodies, Hpid bodies, and starch granules. 

Experiment 5. Observation under transmission electron microscope We compared the TEM ultrastructure of the seed coat and endosperm of control and rue-treated seeds The palisade layer of treated seed appears thicker than in the control (Figs 6A and 7A), while comparison between aleuronic cells of the control and treated cells (Figs. 6B and 7B), reveals that the cells of the control are healthy with some evident organelles such as the nucleus and the rough endoplasmic reticulum and other structures, the plastid, the plasmodesmata, conspicous constrictions, protein bodies and... 

Fig. 6 TEM micrographs of seed coat and aleurone cells of radish control seed 18 h after sowing in water e, epidermis pi, pigment layer al, aleurone layer. (A) Bar = 30 pm Particulars of the aleurone cell showing some organelles nucleus (n), plasmodesmata (pd), protein bodies (pb) and lipid droplets (Id). (B, C). Bar = 5 mm. 

The major rapeseed storage proteins are a 12S type globulin, called cruciferin, which makes up 60% of the total protein, and a 2S type albumin, called napin, which makes up 20% of the total protein [9, 10]. Both of these proteins are formed in embryonic cells and stored in specialized vacuoles known as protein bodies. 

Several different types of proteases hydrolyze intact storage proteins first into large fragments and then into smaller peptides and amino acids within the protein body. The peptides are transported to the cytosol where other enzymes, e. g. amino-peptidases, carboxypeptidases, dipeptidases and tripeptidases, cleave them and eventually form a pool of free amino acids [11]. 

These organelles occur in the endosperm of cereal grains and their structures are tissue specific. They are about 2-5 im in diameter and often contain globoid and occasionally crystalloid inclusions. Prolamin accumulates in small or large spherical bodies. Crystalline protein bodies are the sites of accumulation of nonprolamin storage proteins. 

Microbodies (97-101) are spherical organelles (0.1-2.0 pm in diameter) bounded by a single membrane. They possess a granular interior and sometimes crystalline protein body. A specialized type of microbody is the glyoxysome (0.5-1.5 pm) containing enzymes ofthe glyoxy-late cycle. Glyoxysomes are found in the endosperm or cotyledons of oily or fatty seeds. 

Figure 1. Scanning electron micrograph of Phaseolus vulgaris cotyledon showing protein bodies (P) and starch granules (S). Bar = 10 dm.

Figure 2. Scanning electron micrograph of a mesophyll cell of a dormant cotyledon of Buffalo gourd (Cucurbita foetidissima). Tissue was fixed in aqueous glutaraldehyde, dehydrated with ethanol and critically point dried. Note cell wall (W) and intracellular components including protein bodies (P) and emptied spherosomes that appear as a cytoplasmic reticulum.

Figure 3. Transmission electron micrographs of mesophyll cells of dormant cotyledons of A, Cucurbita foetidissima B, Cucurbita pepo C, Cucurbita palmata D, Cucurbita digitata E, Apodanthera undulata" Note cell wall (W), protein body (P), spherosome (S), globoid (G), and crystalloid (X). In each micrograph, the bar represents five microns. Reproduced from reference 14.

In their raw, natural state, these oils exist in the form of a triglyceride or fat. In order to derive the useful oil from the raw material, the triglyceride must be separated from protein bodies and sterols also present within the oil seed. To illustrate this process, soybean oil production will be briefly described. 

FIGURE 10-3 Fat stores in cells, (a) Cross section of four guinea pig adipocytes, showing huge fat droplets that virtually fill the cells. Also visible are several capillaries in cross section, (b) Cross section of a cotyledon cell from a seed of the plant Arabidopsis. The large dark structures are protein bodies, which are surrounded by stored oils in the light-colored oil bodies. 

Fluorescence microspectrophotometry typically provides chemical information in three modes spectral characterization, constituent mapping in specimens, and kinetic measurements of enzyme systems or photobleaching. All three approaches assist in defining chemical composition and properties in situ and one or all may be incorporated into modem instruments. Software control of monochrometers allows precise analysis of absoiption and/or fluorescence emission characteristics in foods, and routine detailed spectral analysis of large numbers of food elements (e.g., cells, fibers, fat droplets, protein bodies, crystals, etc.) is accomplished easily. The limit to the number of applications is really only that which is imposed by the imagination - there are quite incredible numbers of reagents which are capable of selective fluorescence tagging of food components, and their application is as diverse as the variety of problems in the research laboratory. 

Electron microscopy of radish radicle, a) and b) Details of cortical cells from radicles of 2 h-imbibed control seeds, (a) Note the abundance of protein reserves in protein bodies (PB) and lipid reserves in the peripheral cytoplasm (arrows), (b) Numerous mitochondria (M) are visible among lipid bodies (L). (c-e) Details of cells from radicles of 16 h-imbibed control seeds, (c) Cortical parenchyma cells. The protein bodies have converted into normal vacuoles (V) and lipid reserves have been partially depleted, (d) Detail of epidermal cell showing a plastid (P) containing starch deposits (S). (e) Detail of cortical cell, showing several mitochondria (M) and a microbody (Mb). 

Electron microscopy of radish radicle. Details of roots from seeds treated with 1/14-diluted reverse osmosis fraction, (a) Cortical cells showing protein-body-derived vacuoles (V) with remnants of electron-opaque protein material. Extremely swollen mitochondria (M) look like vacuoles with fine granular contents, (b) Detail of epidermal cell, showing swollen mitochondria (M), lipid droplets (L) and two dictyosomes (D). (c) The area enclosed in the rectangle in (b) is enlarged to show the two-membrane envelope and residual cristae (arrows) in a swollen mitochondrion. 

BHANDARI, N.N., CHITRALEKHA, P., Degradation of protein bodies in germinating seeds of Brassica campestris L. var. sarson Prain., Ann. Bot., 1984,53, 793-801. 

As described earlier, plant self-protection from its own defensive compounds can be variously achieved by localization of the active agents in the cell wall, seed protein bodies and vacuoles and by storage of inactive forms (e.g. inactive glycosylated derivatives of the active aglycone). Further, deposition of active agents in dead protective material such as fruit hull, wood and bark ensures effective defence at the point of predator entry as well as protection of the plant from its own defensive compounds. 

Greenwood, J.S., and Bewley, J.D., 1984, Subcellular distribution of phytin in the endosperm of developing castor bean A possibility for its synthesis in the cytoplasm prior to deposition within protein bodies. Planta 160 113-120. 

Takahashi, H., Rai, M., Kitagawa, T., Morita, S., Masumura,T., and Tanaka, K., 2004, Differential localization of tonoplast intrinsic proteins on the membrane of protein body type II and aleurone grain in rice seeds. Biosci. Biotchnol. Biochem. 68 1728-1736. 

Cyanogenesis is initiated following the hydrolysis of cyanogenic glucosides by 3-glucosidases, which are often referred to as cyanogenic 3-glucosidases. Such enz)mies are localized in the apoplasm, in protein bodies or in... 

Prunus serotina Prunasin -L-L Protein bodies KurokI and Poulton (1987), Swain and Poulton (1995)... 

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