Galactosidases from E. coli

Husum et al. found that the hydrolytic activities of P-galactosidase from E. coli and the protease subtilisin in a 50 % aqueous solution of the water-miscible ionic liquid [BMIM][Bp4] were comparable to those in 50 % aqueous solutions of ethanol or acetonitrile (Entry 9) [37]. 

When the accessible concentration range of glycal [A] c Kj and kpg- c khydr as for ) -D-galactosidase from E. coli, this reduces to k (1 + [S]/ Kp,) = (kp /K,0 [A] + khydf. The rate constant k yj, for the addition of water has to be measured separately, by the appearance of the 2-deoxy-o-hexose. With )S-D-galactosidase from E. and yS-D-glucosidase from... 

In order to account for the inability of many enzymes to bind the protonated form of the basic inhibitors or permanently cationic ones better than uncharged analogs (for example, yS-o-galactosidase from E. coli, and P-v>-glucosidase from almonds), it was proposed that the enzyme could proton-ate the inhibitor at the active site by a cationic acid (for example, protonated histidine). If proton transfer cannot occur, the attractive forces due to the carboxylate would be canceled by the repulsion from the cationic acid. Experimental evidence for this proposal is, however, still lacking. In fi-D-gn-lactosidase from E. coli, a tyrosine is presumed to be responsible for the protonation of substrates. ... 

M. Yde and C. K. De Bruyne, Binding of substituted phenyl 1-thio-P-D-galactopyranosides to P-D-galactosidase from E. coli, Carbohydr. Res., 60 (1978) 155-165. 

Analysis of the activity of f-galactosidase from E. Coli by scanning electrochemical microscopy (SECM)... 

Hydrolysis of p-Nitrophenyl-/ -D-Galactoside with / -Galactosidase from E coli... 

Fig. 2. Postulated interactions of D-glucose (a), D-treitol (b), and L-treitol (c), with the glucosyl site of -galactosidase from E. coli [21]...

Purification of b-galactosidase from E. coli may be compared Higgins (26) outlines a process of succeeding centrifugations to remove cell debris, nucleic acids precipitate, and protein precipitate (product). Veide (23) outlines a single aqueous extraction with PEG and salt in which b-galactosidase partitions to the PEG-rich phase. Cells, nucleic acids, and a major part of the contaminating proteins partition to the salt-rich phase. 

Sedimentation analyses of an activatable mutant jS-D-galactosidase from E. coli and of the products of its reaction with Fab fragments of activating antibody showed that the enzyme exists mainly as lOS dimers. Activations by antibody resulted in formation of 16 S tetramers. A hypothesis postulating a dimer-tetramer equilibrium accounts for this observation as the counterpart of inactivation. 

S-Galactosidase from E. coli (Sigma Chemical Co.) (50 U) no reported risk (1 U will hydrolyse 1.0 p,mol of o-nitrophenyl- 3-D-galactopyranoside to o-nitrophenol and galactose per minute at pH 7.3 and 37 °C)... 

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