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Charakterystyka immobilizowanej katalazy stosowanej w zimnej pasteryzacji mleka

Węgrzynowska L., Trusek-Hołownia A.

Inżynieria i Aparatura Chemiczna

2012

Nr 4

189-191

W artykule scharakteryzowano preparat immobilizowanej katalazy w kapsułkach alginianowych, który ze względu na swoją heterogeniczność może być w łatwy sposób separowany ze strumienia mleka. Aktywność preparatu immobilizowanego w warunkach reakcji (pH 6,4, 24°C) jest o połowę mniejsza aniżeli preparatu natywnego, aczkolwiek jego stabilność w warunkach procesowych jest kilkanaście razy wyższa, dotyczy to również stabilności w warunkach przechowywania.

Immobilized catalase in alginate capsules, easily separated due to its heterogeneity from milk stream, is characterized in the paper. The activity of the immobilized catalase at process conditions (pH 6.4, 24°C) is two times lower than the activity of native catalase, however the stability at process conditions is incomparably better. This also applies to the stability at storage conditions.

Behaviour of glucose oxidase during formation and ageing of silica gel studied by fluorescence spectroscopy

Przybyt M.

Materials Science

2003

Vol. 21, No. 4

397-416

Glucose oxidase was entrapped in silica gels obtained by the sol-gel process with the retention of a part of its activity. The stability of the enzyme molecule during the sol-gel transition and ageing of the wet gel was followed by the measurement of fluorescence of tryptophan and flavin adeninedinucleotide (FAD). The results indicate unfolding and denaturation of the enzyme protein caused by the changes of microenvironment inside gel, presence of ethanol, decomposition of FAD and photosensitised oxidation of tryptophan by FAD. Among the products of FAD decomposition, alloxazine derivatives were identified through their specific fluorescence characteristics. The results of the observation of the fluorescencje variation and activity assay of the gel are in good agreement. The experiments with the dried gel indicato that illumination is not necessary to sensitise the reaction of oxidation of tryptophane by FAD although In the presence of light the effectiveness of this process is higher. Presumably the decomposition of FAD and tryptophan is not only induced by light but also by the paramagnetic (with free radical character) defects in the gel matrix. This reaction is enhanced by the presence of glucose and depends also on pH of the buffer used in the gel preparation. The products of the enzyme degradation are easily washed out from the gel. Leaching of active enzyme from the gel was also observed.