Enzyme breakdown

We may conclude with the statement that not only do the experiments on the enzymic breakdown of starch point directly toward the irregular formula with multiple branchings, but that the results concerned with the acid hydrolysis are explicable on the same assumption. 

Enzyme breakdown One process by which neurotransmitters are inactivated. Chemicals called enzymes interact with the transmitter molecule and change its structure so that it no longer is capable of occupying receptor sites (Chapter 3). 

Enzyme Breakdown of natural substrates Present and potential industrial uses... 

Other compounds also contribute to varietal aroma. Norisoprenoids, not strictly considered terpenes, are produced by the chemical or enzymic breakdown of carotenoids in grapes. They also occur in the form of glycosylated precursors. 

Figure 5 shows a reaction scheme which may explain the formation of Cg- and C-] 2-components in leaves and fruits. Hatanaka et al. (12) proposed a cleaving system operative in Thea sinensis leaves and other plants which is located in the chloroplasts. E2 shows a similar substrate specifity as lipoxygenase E-. The enzymic breakdown products from linolenic acid are ( )-3-hexenal (I) and 12-oxo-( )-9-dodecenoic acid (V). Both constituents are transformed into the corresponding ( )-2-enals by E3 and/or by chemical reactions. During these transformation the carbonyls may be reduced to alcohols by alcohol oxidoreductase E4. In ripe fruits the right pathway E-j, E2f E3 seems to become operative. 

Both proteins are existing in the same cellular compartment i.e. the cytosol. The copperthioneins are very resistant to enzymic breakdown. None of the known proteases are able to attack these proteins. Surprisingly, the copper from these proteins is released offering an appropriate apoprotein or by an oxidative breakdown Therefore,... 

Fish raw material is primarily the whole fish, although fish oil is also extracted from the waste material from fish markets and canning factories. The enzymic breakdown of fish tissue is even more rapid than from the viscera of animals and has more pronounced effects on the oil and its downstream processing. Fish oils are highly unsaturated and are therefore more liable to oxidative breakdown. Virtually all fish oil for human food is hydrogenated and therefore it is particularly important that oxidation products and sulphur compounds, both of which are hydrogenation catalyst poisons. 

Hexokinase activity decreases progressively after the 30th day and reaches 60% of the original activity approximately when the erythrocyte is 90 days old. It is not known whether the loss of enzyme activity results from changes in the rate of enzyme breakdown or from the appearance of inhibitors. A dual mechanism seems to be responsible for hexokinase s loss of activity namely, a net reduction in the number of enzyme molecules and the accumulation of intracellular ADP leading to inhibition of the enzyme. 

Kapeller-Adler, R. and Renwick, R. On the enzyme breakdown of histamine and cadaverine in human serum and urine, Clin. chim. Acta 1, 197 (1956). 

The degradation of ganglioside Goia and sialyl-lactitol by membrane-bound neuraminidase from calf brain has been studied as a fimction of the lipophilic/ hydrophilic character of the substrate. Availability and enzymic breakdown of the ganglioside were enhanced by general anaesthetics such as nitrous oxide and halothane, whereas the degradation of sialyl-lactitol was not affected by... 

The means by which alterations in enzyme levels are brought about are not well understood but it appears that hormones act by altering the rate of enzyme synthesis rather than of enzyme breakdown. This is accomplished by the specific induction or repression of enzymes. This type of... 

Snell el al. examined a sample of coenzyme A supplied by Lipmann for growth factor activity and found it inactive, but coenzyme A treated with intestinal phosphatase was active. Pantetheine (or pantothine) thus arises by enzymic breakdown of coenzyme A. It must therefore be preformed in the coenzyme A molecule. The following structure, proposed by Lipmann, is based on enzymic degradation and resynthesis and may be regarded as established. 

The enzymic system shown in Fig. 4e for the enzymic breakdown of heparin has only been reported in Flav( clerium hejiarinum (Dietrich, 1969). The characteristics of the unique e/irfo-a-A -suifamino-D-gluco-saminidase are yet to be described. 

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