Immobilized enzymes: crystals or carriers?

The advantages of immobilized over soluble enzymes arise from their enhanced stability and ease of separation from the reaction media, leading to significant savings in enzyme consumption. Immobilization methods range from binding to prefabricated carrier materials to packaging in enzyme crystals or powders. During their use, mass-transfer effects can produce substrate or pH gradients, which reduce the reaction rates and product yields.

Improvement of the catalytic properties of penicillin G acylase from Escherichia coli ATCC 11105 by selection of a new substrate specificity.

Cloned penicillin G acylase (PGA) from Escherichia coli ATCC 11105 was mutagenized in vivo using N-methyl-N'-nitro-N-nitrosoguanidine. Mutants of PGA were selected by their ability to allow growth of the host strain E. coli M8820 with the new substrates phenylacetyl-beta-alanyl-L-proline (PhAc-beta Ala-Pro) phthalyl-L-leucine (Pht-Leu) or phthalylglycyl-L-proline (Pht-Gly-Pro) as sole source of proline and leucine respectively.

[BCG-vaccination in neonates as a cause of osteomyelitis--an argument against BCG-vaccination?].

BCG-osteomyelitis is a rare complication of BCG-vaccination. By means of a case report clinical and immunological findings are discussed. Contrary to the undramatic clinical symptoms the x-ray showed pronounced osteolytic lesions in the sternum.

Characterization of D-amino acid oxidase from Trigonopsis variabilis.

D-amino acid oxidase from Trigonopsis variabilis was purified to homogeneity as a well resolved flavoprotein. Specific activity of pure enzyme was 86.6 U/mg at 30 degrees C and pH 8.

Kinetic mechanism of D-amino acid oxidases from Rhodotorula gracilis and Trigonopsis variabilis.

The reaction of two D-amino acid oxidases from the yeasts Rhodotorula gracilis and Trigonopsis variabilis with the substrates alanine and valine in their 2-1H and 2-2H forms was studied employing the stopped-flow spectrophotometric technique. The turnover numbers at infinite substrate and oxygen concentrations were: 20,700/4,250 and 1,730/360 ([2-1H]/[2-2H]alanine and valine, respectively) for the Rhodotorula and 3,150/440 and 2,500/520 ([2-1H]/[2-2H]alanine and valine, respectively) for the Trigonopsis enzymes. The rates of anaerobic enzyme flavin reduction were 20,100/4,000 and 1,820/350 ([2-1H]/[2-2H]alanine and valine, respectively) for the Rhodotorula and 3,470/350 and 2,460/480 ([2-1H]/[2-2H]alanine and valine, respectively) for the Trigonopsis enzymes.