Differential inactivation

Kaczorowski G, L Shaw, R Laura, C Walsh (1975) Active transport in Escherichia coli B membrane vesicles. Differential inactivating effects from the enzymatic oxidation of P-chloro-L-alanine and P-chloro-D-alanine. J Biol Chem 250 8921-8930. 

Gravesen, A., Diao, Z., Voss, J., Budde, B.B., and Knochel, S. 2004. Differential inactivation of Listeria monocytogenes by D- and L-lactic acid. Letters in Applied Microbiology 39 528-532. 

Direct evidence for the above proposal was obtained with the demonstration that separable cyclases derived from sage (Salvia officinalis) synthesize monoterpene olefins of opposite stereochemistry (74,76). Thus, cyclase I, of MW 96,000, converted GPP to (+)-a-pinene, (+)-camphene and (+)-llmonene of related configuration, whereas cyclase II, of MW 55,000, transformed the same achiral precursor to (-)-B-plnenc in addition to (-)-a-pinene, (-)-camphene and (-)-limonene. Extensive purification of each enzyme and differential inactivation studies ensured that each set of stereochemlcally related products was synthesized by a single, distinct enzyme (74). Since ( )-LPP had been shown to serve as a precursor for both enzymes (76) it was possible to directly assess the absolute configuration of the tertiary intermediate cyclized, by the preparation and separate testing of each enantiomer. As predicted by the general model (Fig. 3), 3R-LPP preferentially... 

Some other techniques of protein precipitation, like differential inactivation by temperature or pH, have been occasionally used for those cases where abnormal stability allows the enzyme to retain its functional structure while contaminant proteins are precipitated by irreversible unfolding (Prado et al. 1999 Harris 2001). 

In a subsequent examination of the cyclases that formed ( 4-)- and ( — )-pinene, cyclase 1,96,000 MW, converted geranyl pyrophosphate to (-1-)-a-pinene (d-a-pimm) (14), but produced smaller amounts of (-b)- or if-camphene (15) and (+)- or /-limonene (11) as side products (Johnson and Croteau, 1987). Cyclase II, 55,000 MW, transformed geranyl pyrophosphate into ( —)-p-pinene (/- -pinene) (16) along with smaller amounts of /-a- or (— )-a-pinene, (-)- or /-camphene, ( —)- or /-limonene, and myrcene (17) as coproducts (Fig. 19.7) (Croteau, 1984 Johnson and Croteau, 1987). Extensive purification of each enzyme and differential inactivation studies ensured that each set of stereochemi-cally related products was synthesized by a single, distinct enzyme. 

It should be noticed that in this case the differential inactivation is specifically restricted to the nucleolar organizer region, because many enzymes which are controlled by paternal as well as maternal genes were active (Wall and Blackler,... 

The controlled chemical modification of chloroplast thylakoids with glutaral-dehyde (GA) that results in the strong inhibition of the Pi-ATP exchange while ATP formation and hydrolysis are only slightly impaired (Table 1), is another example of such a differential inactivation of CFl catalyzed activities. 

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