Immunological relatedness between beta-galactosidases of different bacterial origins.
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Antibodies, Bacterial↗
Biomedical subjects
N Guiso
Publications and source records attributed to N Guiso.
An immunological determination of specific activities of enzymes: its use in quantification of cross reactivity between enzymes of different origins.
An immunological method is presented which enables the determination of the specific activity of a pure enzyme without its extensive purification. The method consists essentially in the specific fixation of immunologically related enzymes to an immunoadsorbent containing specific antibodies raised against the wild-type form of the enzyme. We applied this method to determine the specific activity of plasmid-coded beta-galactosidases and to quantify the extent of cross-reaction between these enzymes and Escherichia coli beta-galactosidase.
Animals↗
[Positivity of ONPG test versus the presence of beta-galactosidase in Enterobacteriaceae and other Gram-negative bacilli (author's transl)].
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Bacteria↗
Expression and regulation of lactose genes carried by plasmids.
A number of plasmids carrying the lactose character have been studied. All of the plasmids examined so far code for proteins essential for lactose utilization, i.e., beta-galactosidase and galactoside permease. None of them carries enzymatically or immunologically detectable thiogalactoside transacetylase. The expression of the two enzymes is both negatively and positively controlled: they are inducible by different galactosides and are sensitive to catabolite repression. Since the plasmid-coded lactose systems have many features in common with the Escherichia coli lactose operon, it is suggested that the plasmids could have acquired the lactose genes from an E. coli chromosome.
Acetyltransferases↗
The threonine-sensitive homoserine dehydrogenase and aspartokinase activities of Escherichia coli K12. Distribution and accessibility to antibodies of some epitopes of the bifunctional enzyme.
In the presence of l-threonine, the allosteric effector, most of the antigenic determinants situated in the aspartokinase region of the wild-type enzyme become unavailable to the antibodies raised against a fragment of the enzyme containing this region and devoid of homoserine dehydrogenase activity. The cross-reactivities of the antibodies raised against this fragment (extracted from a nonsense mutant) and a fragment endowed with homoserine dehydrogenase activity but devoid of aspartokinase activity (obtained by limited proteolysis) with the corresponding antigens were studied. The conclusion is drawn that the two fragments, which share an overlapping sequence of molecular weight about 17,000, share at least two antigenic determinants.
Alcohol Oxidoreductases↗
Evolution of biosynthetic pathways: immunological approach.
Through the use of specific immunoadsorbent columns, it is shown that Escherichia coli aspartokinase I-homoserine dehydrogenase I, aspartokinase II-homoserine dehydrogenase II, aspartokinase III, and homoserine kinase, enzymes involved in the same complex biosynthetic pathway, share antigenic determinants. This raises the question of a common origin for the four cibtenoirart kinases. (Aspartate kinase or ATP:L aspartate 4-phosphotransferase, EC 2.7.2.4; homoserine dehydrogenase or Lhomoserine:NADP oxidoreductase, EC 1.1.1.3; homoserine kinase or ATP:L-homoserine O-phosphotransferase, EC 2.7.1.39.)
Alcohol Oxidoreductases↗