Yeast breakage

This indicates that endosulfan is capable of inducing chromosome breakage and loss. Endosulfan also induced cytotoxic activity (significant increase in the number of crossover colonies) in the yeast strain S. cerevisiae T2 (deficient in repair system), but not in S. cerevisiae T1 (L Vova 1984). 

Contopolou, C.R., Cook, V.E., Mortimer, R.K. (1987). Analysis of DNA double-strand breakage and repair using orthogonal field alternation gel electrophoresis. Yeast 3,71-76. 

Microbial cell-wall-lytic enzymes are widely used in the laboratory for cell breakage, proto-plasting of yeasts and bacteria, and for studies of the structure and composition of microbial cell walls (J ). Recently lytic systems have come under consideration as a specific and chemically mild way to rupture microbial cells on an industrial scale (2 ). There appear to be attractive commercial applications of lytic systems for the recovery of enzymes, antigens and other recombinant products accumulated within cells, for upgrading of microbial biomass for food and feed uses (4 5) and for the manufacture of functional biopolymers from cell wall carbohydrates (6). 

A limitation of both models is overestimation of the amount of protein released. Peptide predictions by the simple model are too high as well. The effect resembles a gap in the material balance, as if the models predict a larger quantity of proteinacious material than is actually present in the cells. Possibly some cytoplasmic proteins are not released during protoplast breakage. In figure 6, insoluble proteins could account for a substantial part of the residual yeast at 90 minutes digestion. 

Human CGL displays an interesting substrate specificity with clear preference of C-S over S-S bond breakage L-cysteine and L-cystine are converted orders of magnitudes more slowly than the natural substrate L-cystathionine. The yeast enzyme attacks the C-/3-S bond of L-cystine or L-cysteine, whereas the streptomyces enzyme is quite active toward L-cystine. A CGL enzyme from Lactococcus lactis was reported to consist of at least six identical subunits and have a broad substrate specificity and relatively low specific activity toward L-cystathionine compared to bacterial CGL. In humans, L-cystathionine is split almost exclusively in... 

The primary KIEs for the spontaneous hydrolysis of 12 (1.018, corrected to 25°C) and the yeast a-glucosidase-catalyzed hydrolysis of 10 (1.019) suggested transition states with partial C-N bond cleavage. Similar results were found in a study by Scheming and Schramm on pertussis toxin-catalyzed hydrolysis of NAD. ° Based on the family of KIEs (primary KIE value of 1.021), semi-empirical calculations and BOVA, these authors concluded that the reaction transition state had partial C-N bond breakage with a weak nucleophilic component from the incoming water molecule. 

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