Citrus protein

Citrus juices and their products cannot be considered significant dietary sources of protein because the protein efficiency ratio (PER) of citrus protein is less than 20% that of casein (23, 41). 

When cell-wall fragments are incubated in molar NaCl, ionically bound proteins are released into the incubation medium. All investigated crude cell extracts deesterified Citrus pectin (Table 2) but the deesterification rates were clearly higher when the enzymes were still bound to the cell walls, indicating a major loss of activity during the solubilization process. 

The basal medium of Mandels (Mandels et al., 1976) was used with the following modifications it was buffered with 3 g/1 of sodium nitrate to pH 5.5 and supplemented with 1% w/v citrus pectin " Sigma" or other carbon sources. For enzyme production, 50 ml medium in 250 ml erlemneyer flasks were inoculatedwith spores (10 spores /ml ) exept for the non sporulating Pol 6 strain, where mycelium was used. The culture were incubated at 30° C on a rotary shaker (150 rev mn -1) for 5 days. The culture broth was filtered (Millipore 0.45 pm ) and the supernatant was analysed for pectinolytic activities, reducing sugars and proteins. 

The strains were cultured on Mandels medium + 1% citrus pectin for 5 days and the enzymatic activities of culture filtrates were determined on three substrates citrus pectin, polygalacturonic acid and filter paper, (a) extracellular proteins are in p.g/ml. (b) p>ectinolytic activities on pectin (PC) and on polygalacturonic acid (TO) and Pectin esterase (PE) are in units/ml. (c) total cellulolytic activity (filter paper, fp) are in mg of liberated reducing sugars/ml. 

The substrates used were PC citrus pectin E orange peel G glucose, Gly gycerol, APG polygalacturonic acid. Results of two cultures (1 and 2) are presented. On ordinates, specific activities (Activity Units par p,g of extracellular proteins) are presented. Note the ordinates scale differs from one histogramme to another. 

Citrus paradisi fruit tissue chalcone cyclase protein — - Y[64]... 

Citrus species are well-known for their accumulation of flavone- and flavanone-glycosides, and thus should contain all of the enzyme activities necessary for the synthesis of these compounds. Two tentative consensus sequences for FNS-II have been identified by in silico analysis of the CitEST database, apparently representing the first identification of putative FNS-II genes in this genus [29]. Biochemical determination of function and analysis of the proteins encoded by these genes will be an important step toward elucidating flavone synthesis in Citrus. 

Much of the FLS biochemical and structure/fimction analysis has focused on a protein from C. unshiu (mandarin). A cDNA was isolated based on sequence homology to an Arabidopsis FLS EST (153O10T7) and used as a probe to determine regulation of gene expression [92]. Higher expression was observed in young leaf, flower, peel, and juice sac/segment epidermis tissues. Expression decreased with tissue age, as has been observed for citrus CHS, CHI, and F3H [57]. Southern analysis... 

Such a system has been used for the comprehensive 2D chromatography of proteins [9,14], synthetic polymers [16], oxygen heterocyclic fraction of cold-pressed citrus oils [22,29], carotenoids [39], triglycerides in fats and oils [18-21], pharmaceuticals [29], and acidic and phenolic compounds [27,28]. 

Since the acetal exists in equilibrium with the aldehyde, it is possible for the aldehyde to be released when water is added in a mixed drink, changing the balance and giving a burst of freshness to a mixed drink. Ethyl esters of terpene alcohols in citrus oils and other botanicals, plus the ethyl esters of fatty and volatile acids, are formed during prolonged exposure to ethyl alcohol. Certain beverage alcohol products that need to contain milk, eggs, or other protein containing materials must be developed carefully and the added flavors must be considered to prevent the precipitation of the protein and separation of the product. 

Borradaile NM, de Dreu LE, Huff MW. 2003. Inhibition of net HepG2 cell apolipo-protein B secretion by the citrus flavonoid naringenin involves activation of phosphatidylinositol 3-kinase, independent of insulin receptor substrate-1 phosphorylation. Diabetes 52 2554-2561. 

The energy-supplying nutrients are generally carbohydrates, protein and fat. While citrus products provide little protein and fat, their contribution of carbohydrate is an essential part of the nutritive value of citrus. The proximate composition of several kinds of citrus fruits (8) are shown in Table II. Because... 

The amount of protein in citrus fruit is relatively low (Table II), and the juice and peel have about the same amount (29). Much of the value that is considered as protein is either free amino acids or non-protein constituents which contain nitrogen. 

The total nitrogen of orange juices was found to increase with the maturity of the fruit and ranged between. 068 to. 120 g per 100 ml (30). The actual protein values obtained by Clements (31) were about 20 percent of the acetone powder. Nearly 30 percent of the alcohol-insoluble solids of juice and about 20 percent of that of vesicular pulp were found to be protein as determined by the Kjeldahl procedure (32). These values are the actual protein that was precipitated by alcohol and are only a fraction of the total protein values usually reported for orange juice (8). The main source of proteins in citrus juice is probably in the form of enzymes and the plastids. At least 47 different enzymes have been reported to occur in citrus fruits (33). Citrus fruits also contain several phenolic amines (34), some of which such as syn-epherine, may have physiological importance (35). 

More recently, Manabe (3A) purified PE from Citrus natsudaidai fruit by chromatography on a DEAE-cellulose column followed by Sephadex G-100 column adsorption of the active fraction. The final preparation was homogeneous as determined by disc electrophoresis and was A60 times as active as the original extract on a protein basis. 

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