Galactosidasic enzymatic activity

Isolation of alkaline phosphatase from Escherichia coli in which 85% of the proline residues were replaced by 3,4-dehydro-proline affected the heat lability and ultraviolet spectrum of the protein but the important criteria of catalytic function such as the and were unaltered (12). Massive replacement of methionine by selenomethionine in the 0-galactosidase of E. coli also failed to influence the catalytic activity. Canavanine facilely replaced arginine in the alkaline phosphatase of this bacterium at least 13 and perhaps 20 to 22 arginyl residues were substituted. This replacement by canavanine caused subunit accumulation since the altered subunits did not dimerize to yield the active enzyme (21). Nevertheless, these workers stated "There was also formed, however, a significant amount of enzymatically active protein in which most arginine residues had been replaced by canavanine." An earlier study in which either 7-azatryptophan or tryptazan replaced tryptophan resulted in active protein comparable to the native enzyme (14). 

In most cases, missing jS-galactosidase activity will be associated with GM1-gangliosidosis. The differential diagnosis between GM1-gangliosidosis and Morquio type disease must be based on the clinical evaluation of the patient because the enzymatic activity alone will not be helpful. 

Several laboratories have studied the assimilation of specific lysosomal enzymes using as model systems skin fibroblasts deficient in the enzyme under study. The underlying mechanism for the translocation of lysosomal enzymes was hypothesized to involve binding of carbohydrate-containing recognition markers to specific cell surface receptors (1 5). In support of this hypothesis Hickman, Shapiro, and Neufeld (16J found that treatment of N-acetyl-B-hexosaminidase with periodate under conditions that dTd not affect enzymatic activity prevented the efficient assimilation of this enzyme by Sandhoff fibroblasts. Additionally, Kresse and von Figura (1 7) found that treatment of f -acetyl-a-hexosaminidase with B-galactosidase reduced the assimilation of this enzyme by San-filippo B fibroblasts. 

Many tissues from patients with I-cell disease exhibit normal levels of intracellular lysosomal enzymatic activities (e.g., brain, liver, kidney, and spleen). In the liver, lysosomal enzyme levels are normal except for diminished P-galactosidase and elevated P-hexosaminidase, P-xylosidase.and a-galactosidase. This fairly spe-... 

Neutral lactase (p-Galactosidase) is an enzyme produced on an industrial scale, which catalyzes the hydrolysis of lactose. Industry utilizes this enzyme in the production of low-lactose dairy products, whey treatment, and fermented lactic products. The goal of this study is to demonstrate that a new colorimetric method to measure the enzymatic activity is adequate for use as a standard method. 

When the virus was used to infect a known, fully permissive cell line from Spodoptera frugiperdaf both genes were expressed. CAT activity was detected early in the infection at about six hours, a not surprising result since the RSV LTR contains an RNA polymerase II promoter and this enzymatic activity, pre-existing in the cell, should be amongst the first to act on the viral chromosome. Late in the infection, at the time that the polyhedrin promoter is known to become active, P-galactosidase activity was detected. 

The [3-galactosidase analog consists of two subunits a large dimeric polypeptide (200 kDa), denoted enzyme acceptor (EA)2, and a small polypeptide (20 kDa), denoted enzyme donor (ED). (EA)2 and ED are enzymatically inactive but spontaneously associate to give enzymatically active tetramers. In CEDIA assays, [45,46] the hapten or analyte is covalently linked to the ED, and an analyte-specific antibody is used to inhibit the assembly of the enzymatically active tetramers. Analyte in a patient s serum competes with the analyte in the analyte-ED conjugate for antibody, modulating the amount of active B-... 

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