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Thermostability conditions and catalytic characterization of isocitrate dehydrogenase from Bacillus licheniformis

100%

Zabielski P.

Biotechnologia

2001

nr 3

219-230

The NADP+ - dependent isocitrate dehydrogenase (IDH) from Bacillus licheniformis was partially purified using ammonium sulphate fractionation and gel filtration on Sephadex G-200 column. The enzyme preparation had specific activity of 1.52 U mg-1. The temperature optimum for the IDH activity was about 59C. The Arrthenius activation energy was determined to be 65.3 kJ/mol below 47C, and 18.3 kJ/mol above this temperature. The IDH activity at 65C was much protected by isocitrate and magnesium, but no NADP+. Manganese ions were more efficient activators of the enzyme than Mg2+. Calcium ions rather inhibited the IDH. The Km values for DL-isocitrate and NADP+ in phosphate buffer (pH 7.4) at 20C were 85.5 and 4.9 muM, respectively; at 58C the corresponding values were 181.5 and 69.3 muM.

Preparation, properties and suitability of thermostable enzymes

88%

Synowiecki J.

Biotechnologia

1998

nr 3

98-105

Some enzymes from extreme thermophiles and hiperthermophiles have half-lives up to 13h at ,temperatures above 100?C. They are suitable for starch and whey processing, oil mining, PCR techni and oligosaccharides synthesis. The differences in structure and function between these very stable and the prevailing less stable enzyme forms are relatively small and are comparable with those differences found among enzymes of similar stability. The relationship of both conformational stability and enzymatic activity with protein flexibility suggests that stability at temperatures far above those which are optimum for the growth of microorganism is rather unlikely.

Improvement of beta-galactosidase properties and conditions for its microbial biosynthesis

88%

Bednarski W. , Kowalewska-Piontas J.

Biotechnologia

2000

nr 2

131-141

We present examples of genetic modification of microorganisms capable of beta-galactosidase synthesis. The technological characteristics as termostability, high activity in a low temperature is improved. We also describe intensification of beta-galactosidase secretion to the medium.