Construction of deoxyriboaldolase-overexpressing Escherichia coli and its application to 2-deoxyribose 5-phosphate synthesis from glucose and acetaldehyde for 2'-deoxyribonucleoside production.
ABSTRACT The gene encoding a deoxyriboaldolase (DERA) was cloned from the chromosomal DNA of Klebsiella pneumoniae B-4-4. This gene contains an open reading frame consisting of 780 nucleotides encoding 259 amino acid residues. The predicted amino acid sequence exhibited 94.6% homology with the sequence of DERA from Escherichia coli. The DERA of K. pneumoniae was expressed in recombinant E. coli cells, and the specific activity of the enzyme in the cell extract was as high as 2.5 U/mg, which was threefold higher than the specific activity in the K. pneumoniae cell extract. One of the E. coli transformants, 10B5/pTS8, which had a defect in alkaline phosphatase activity, was a good catalyst for 2-deoxyribose 5-phosphate (DR5P) synthesis from glyceraldehyde 3-phosphate and acetaldehyde. The E. coli cells produced DR5P from glucose and acetaldehyde in the presence of ATP. Under the optimal conditions, 100 mM DR5P was produced from 900 mM glucose, 200 mM acetaldehyde, and 100 mM ATP by the E. coli cells. The DR5P produced was further transformed to 2'-deoxyribonucleoside through coupling the enzymatic reactions of phosphopentomutase and nucleoside phosphorylase. These results indicated that production of 2'-deoxyribonucleoside from glucose, acetaldehyde, and a nucleobase is possible with the addition of a suitable energy source, such as ATP.
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ABSTRACT: Diet and gastric cancer mortality in Portugal was studied using a multivariate ecological model. The factors investigated over 18 districts were the relationship between gastric cancer mortality (1994-96), dietary habits, and socio-economic factors (1980-81). Mortality geographical pattern was established using age-standardized mortality rates, per capita dietary consumption of foodstuffs and nutrients was obtained from the National Alimentary Survey (1980-81), and data on socio-economic factors from the 1981 National Census. Pearson correlation coefficients and simple and multiple linear regression models were used. The mortality geographical pattern resembled a north-south gradient, and dietary habits and socio-economic factors had great variability throughout the country. The highest negative correlation coefficients between dietary consumption and gastric cancer mortality were obtained for vegetables, fruit, vitamin A and carotene consumption, and the highest positive coefficients were for rice, wine and carbohydrate consumption. No significant correlations were obtained for socio-economic factors. In multiple regression analysis, vegetable and rice consumption could account for 79% of the gastric cancer mortality variability for males, and vegetable and meat consumption could account for 69% of this variability for females. Interestingly, meat consumption was found to be protective. A mean increase of 100 g/person/day in vegetable consumption would imply a mean predicted decrease of 10 (95% CI 6-14) and 5 (95% CI 3-7) gastric cancer deaths per 100,000 persons/year, for males and females respectively, in simple regression analysis. Such a decrease represents about one-third of the mean national gastric cancer mortality rate. Therefore, an increase in vegetable consumption is strongly recommended.European Journal of Cancer Prevention 03/1999; 8(1):41-8. · 2.13 Impact Factor