A-D-Galactosidase

Group (c), a-D-mannosidase from jack beans and from almonds, and a-D-galactosidase from coffee beans, showed no inactivation. The results with these enzymes can possibly be explained by the formation of a (weak) non-covalent complex in which glycosylation is too slow to cause inactivation within the time period of measurements, or, less likely, rapid hydrolysis of the glycosyl-enzyme intermediate. 

Fic. 12.—Sequence of the Glycosphingolipid Shown in Fig. 11, after Enzymic Degradation with a-D-Galactosidase. (Cleavage points, and the masses of fragment ions of the permethy-lated derivative, are shown.)... 

A list of entrapped enzymes is given in Table 3.2. There are two endo-l,3-P-D-glucanases from marine mollusks Spisula sacchalinensis and Ch. albidus and a-D-galactosidase from marine bacterium Pseudoalteromonas sp. MM 701. They were selected for immobilization for the following reasons ... 

Scheme 4 6 -0-Acyl-lactose (acetyl, propionyl, butyryl) derivatives prepared via the selective enzymatic acylation of lactose by the protease subtilisin were used as acceptors for enzymatic transglycosylations catalyzed by a-D-galactosidase from Talaromyces flavus, forming iso-globotriose a-Gal(l -> 3)-p-Gal-(l -> 4).92 (/) Protease N, pyridine, 37 °C (ii) a-galactosidase from Talaromyces flavus.

T. B. Mercer, S. F. Jenkinson, B. Bartholomew, R. J. Nash, S. Miyauchi, A. Kato, and G. W. J. Fleet, Looking glass inhibitors Bote enantiomeric IV-benzyl derivatives of l,4-dideoxy-l,4-imino-D-lyxitol (a potent competitive inhibitor of a-D-galactosidase) and of l,4-dideoxy-l,4-imino-L-lyxitol (a weak competitive inhibitor of a-D-galactosidase) inhibit naringinase, an a-L-rhamnosidase competitively, Tetrahedron Asymmetry, 20 (2009) 2368-2373. 

The frequent occurrence of sialylated enzymes, or even of multiple forms, which are sometimes tissue-dependent, with a varying number of sialyl residues as, for example, in y-glutamyltranspeptida.se (EC 2.3.2.2),456,457 is not yet fully understood. Although the activity of most of these enzymes is not influenced by removal of sialic acid,454 the activity of monoamine oxidase A (EC 1.4.3.4) of outer mitochondrial membranes of rat liver has been shown to be destroyed by treatment with sialidase438 the substrate specificity of acetylcholinesterase (EC 3.1.1.7) is altered,459 the kinetic properties of human acid and alkaline phosphatases (EC 3.1.3.1 and 3.1.3.2) are changed, and the stability of a-D-galactosidase (EC 3.2.1.22) is drastically lowered.415 In these cases, an influence of sialyl residues on the conformation of the enzyme is assumed, but awaits firm evidence. 

It is at present unclear whether the different clearing-mechanisms of rabbit erythrocytes observed after treatment with sialidase and a-D-galactosidase, respectively, are mediated by two different antibodies, one causing sequestration by macrophages after deposition of C3b complexes on the erythrocyte surface as the second step in the aforementioned mechanism, and the other leading to intravascular destruction of erythrocytes by activation of the whole complement cascade. 

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