Biochemical Degradation

It has been known for some time that the albuminous seeds of the family Leguminosae contain, in the endosperm, galactomannan as the reserve polysaccharide. The exalbuminous seeds, on the other hand, have the main reserve in the cotyledon in the form of starch, oil, and proteins.198,199 The seed galactomannan-reserves are generally mobilized during the process of germination.43,57,81,82,199-205 Detailed study 

During the third, and final, phase (24 h following the second phase), galactomannan is absent (see Fig. 5), and the endospermic carbohydrates of low molecular weight also disappear completely and rapidly. Cotyledons, however, have a high level of starch (see Fig. 4). 

Reid and Meier201 found that the breakdown of galactomannan in isolated, fenugreek endosperms is strongly inhibited by cycloheximide 

According to Reese and Shibata,221 the biodegradative hydrolysis of galactomannan requires at least three different enzymes, namely, a-D-galactosidase, endo-/3-D-mannanase, and j3-D-mannosidase. In addition to these enzymes, there is also a report222 of a phosphorylase, identified as oligo-j8-D-mannosyl-(l— 4)-phosphorylase, which may take part in the degradation. These enzymes will now be discussed in detail. 

Under suitable conditions, the enzyme can also catalyze de novo syntheses of oligosaccharides and transfer reactions.223,224 

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Wastewater. Phenol is a toxic poUutant to the waterways and has an acute toxicity (- 5 m g/L) to fish. Chlorination of water gives chlorophenols, which impart objectionable odor and taste at 0.01 mg/L. Biochemical degradation is most frequently used to treat wastewater containing phenol. Primary activated sludge, along with secondary biological treatment, reduces phenol content to below 0.1 mg/L (69). 

In slow filtration, much of the effect is obtained by the formation of a filtration layer, including the substances that are extracted from the water. At the early stages of the operation, these substances contain microorganisms able to effect, beyond the filtration, biochemical degradation of the organic matter. This effect also depends on the total surface of the grains forming the filter material. The probability of contact between the undesirable constituents of the water and the surface of the filter medium increases in proportion to the size of the total surface... 

Coury A. Chemical and biochemical degradation of pol3Tners. In Ratner B, Hoffman A, Schoen F, and Lemons J (eds). Biomaterials Science An Introduction to Materials in Medicine. Boston, MA Elsevier Academic Press, 2004, pp. 411 30. 

Physico-chemical properties. Chemical and biochemical degradation pathways and physical mechanisms of removal or disappearance by transport process govern the fate of agrochemicals in the environment. Therefore, the physico-chemical properties of the chemical listed below regarding persistence in sediment or water are important ... 

The properties, behaviour under biochemical degradation conditions in WWTPs as well as the extraction, concentration and ionisation efficiency of the fluorine-containing surfactants were described in the literature [49,51]. 

The residues of LAS and ABS detected in the three investigated water streams entering Laguna de Bay could be further reduced by dilution, or biochemical degradation (mainly for LAS). Removal of the surfactants through sorption and precipitation had also been taken into account. This elimination route was particularly important for ABS since many of its derivatives were rather insoluble [26]. 

Compared to the nasal and rectal routes, the buccal mucosa has low enzymatic activity, and drug inactivation due to biochemical degradation is not as rapid and extensive [8]. 

Figure 23.4 Surface mixed sediment layer (SMSL) of thickness zmjx above a permanent sediment. The processes are A = particle settling, B = transfer into permanent sediment, C = diffusive exchange, D = resuspension, E = chemical or biochemical degradation.

E. Chemical or biochemical degradation in the SMSL, k mC. Since the dissolved phase concentration is proportional to Cssc, the reaction rate, k, if multiplied with the corresponding fraction,, could also be used to account for degradation occurring in the dissolved fraction. 

Nord, F. F. (1964). The formation of lignin and its biochemical degradation. Geochim. Cosmochim. Acta 28,1507-1521. 

Besides drift of pesticides during application, air-surface exchange, dry and wet deposition from the atmosphere, and groundwater are all pathways for POPs to enter soil. The sinks of pesticide POPs in soil include biochemical degradation, evaporation, and erosion. Because soil is a nonfluid media, the spatial distribution of pesticide POPs has large differences and is closely related to the application of pesticides, irrigation, and plant coverage. 

Much will depend here on the outcome of the present study of the metabolic fate of organotin compounds under environmental conditions. It is generally accepted that the basic types of organotin compounds are subject to the following generalized pattern of physical, chemical and/or biochemical degradation ... 

Plants. Biochemical degradation leads to the metabolite 2-nitropropan-l,3-diol... 

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