Chlorophyllase, activity

Degreening of peel has been related to chlorophyllase activity. Barmore (14) demonstrated that chlorophyllase activity in peel increased following treatment of fruit with ethylene. 

Except for the slower demise of chlorophyl1-c, the alteration of chlorophyll-a during senescence and death can be attributed to cellular decompartmentalization and resultant action of cellular acids (Mg-loss) and enzymes (e.g chiorophyllase, phytol loss, 35) The relative amounts of pheophytin-a versus pheophorbide-a resulting from senescence-death has been shown to be species specific and is related to chlorophyllase activity (37). Sediment Trap Samples. The alteration of chlorophyll due to senescence/death phenomena, described above, yield a certain suite of pigments. Such arrays, dominated by pheophytin-a, might be expected to form the precursor complement in sediments deposited in an environment free of consumers. Such is obviously not the case in nature. Since the vast majority (e.g. 95-99%) of primary production serves as fodder in marine food webs (38) we must consider heterotrophic alteration of detrital tetrapyrrole pigments. 

No phytol-free pigments were detected in green beans. In the same study, chlorophyllase activity was induced in unheated cucumbers by holding them in 7.5% sodium chloride solution at room temperature. 

Figure 3. Chlorophyllase activity expressed as percent conversion of chlorophyll to chlorophyllide, In spinach during growth (solid line) and after storage at 5°C (broken line).

OGURA N, UENO M, MATSUNAGA M, SATO T and NAKAGAWA H (1987), Chlorophyllase activities and color changes of fresh green leaves on blanching , Nippon Nogeikagaku Kaishi, 61, 451-456. 

FANG z, BOUWKAMP jc and SOLOMOS T. 1998. Chlorophyllase activities and chlorophyll degradation dnring leaf senescence in non-yellowing mutant and wild type of Phaseolus vulgaris L. J Exp Bot 49 503-510. 

MOLL WAW, DE WITT B and LUTTER R. 1978. Chlorophyllase activity in developing leaves of Phaseolus vulgaris L. Planta 139 79-83. 

Storage of natural seston at low temperatures (-20 °C) for up to five months has no effect on seston samples stored diatom culture material, however, showed considerable compositional changes after only one month. This has been attributed to ongoing chlorophyllase activity. Jeffrey and Hallegreef (1987) also reported on potential problems associated with enzymatic chlorophyll degradation. Thus, samples rich in phytoplankton should be extracted as soon as possible after collection the extracts can then be stored deep-frozen for up to five months with only minor changes. 

The extent of the reaction converting chlorophylls into pheophytins is directly related with the temperature and the time that the blanching treatment lasts [132]. Blanching at low temperature (65°C-80°C) favors activation of the enzyme chlor-ophyllase, and thus the formation of dephytylated chlorophyll derivatives (chloro-phyllides and pheophorbides). At higher temperatures (around 100°C), the enzyme is partially inactivated, but is favored the parallel reaction of pheophytinization. The extent of chlorophyllide and pheophorbide formation will depend not only on the specific conditions of the technological treatment, but also on the level of chlorophyllase activity in the plant material [133]. 

Mfnguez-Mosquera, M.I., Gandul-Rojas, B., and Gallardo-Guerrero, M.L., Measurement of chlorophyllase activity in olive fruit (Olea europaea), J. Biochem., 116, 263, 1994. 

Commercial production of the pigments in England was described by Humphrey (49). Chlorophyll is extracted from dried grass or alfalfa with acetone or chlorinated hydrocarbons. Sufficient water is added, depending on the moisture of the plant material, to aid in penetration of the solvent while avoiding activation of chlorophyllase enzyme. Pheophytin may be acid hydrolyzed before copper ion is added resulting in the formation of water soluble copper chlorophyllin. 

Chlorophyllase is an intrinsic membrane glycoprotein situated in the thylakoid membrane (Terpstra, 1981). It does not normally interact with its chlorophyll substrate, although chlorophyll is situated in the same membrane. In intact plant tissue, chlorophyllase is kept in an inactive and stable conformation by the adjacent lipids of the thylakoid membrane (Lambers and Terpstra, 1985). In order to activate chlorophyllase, a substantial disruption of the thylakoid membrane has to... 

Formation of ATP from ADP via the cyclic photophosphorylation system Active immobilized enzyme Investigation of the role of the molecular environment on chlorophyllase functioning during its immobilization Active immobilized enzyme... 

Preparation of a Photoaffinitv Label Containing Chlorophvllide a. ChiorophyHide a was prepared from chlorophyll a extracted from spinach and purified by powdered sucrose column chromatography by the method of Strain and Svec (16). An acetone powder of chlorophyllase was prepared from spinach by the method of Tanaka et al. (17) and used to hydrolyze the purified chlorophyll a. The product was extracted with acetone 0.01 M ammonia (9 1) and washed with n-hexane to remove unreacted chlorophyll. It was then covalently attached to Sepharose CL-4B (Pharmacia) after activation of the gel with CNBr by the method of Richards et al. 

In vegetable foods subjected to lactic acid fermentation, activity of the enzyme chlorophyllase is very often favored during the process, and dephytylated chlorophyll derivatives are found [133,138-141]. The degradation mechanism proposed is as follows ... 

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