Biomedical subjects

K Smalla

Publications and source records attributed to K Smalla.

21 records · Page 2Linked to original sources

PubMed1989

[Risk assessment of the industrial application of genetically engineered microorganisms].

Factors affecting the persistence, dissemination of GEM's and their gene transfer to indigenous microorganisms are important in assessing potential risks posed by environmental release of GEM's. Risk assessment should essentially contain case studies of the extent and ways of release, GEM stability and gene transfer under laboratory and in situ-conditions. Some aspects of a risk assessment study for the industrial production of alpha-Amylase from a genetically engineered Bacillus subtilis strain are discussed.

Bacteria↗

PubMed1988

Influence of salts on the covalent immobilization of proteins to modified copolymers of 2-hydroxyethyl methacrylate with ethylene dimethacrylate.

In the study of the covalent immobilization of aminoacylase, thermitase, pepsin, trypsin, chymotrypsin, elastase, subtilisin, penicillinamidohydrolase, carboxypeptidase A, cystathionine-beta-synthase, and anticathepsin D-IgG to copolymers of 2-hydroxyethyl methacrylate and ethylene dimethacrylate (Separon HEMA) containing epoxy groups a marked influence of added salts on the immobilization efficiency was observed. Yields in covalently bound active enzymes were dependent on the concentrations and type of ions added, which can be arranged according to the Hofmeister series. At a distinct concentration, the salting-out ions cause a protein-matrix hydrophobic interaction which is a prerequisite for the covalent bond formation.

Cross-Linking Reagents↗

PubMed1984

[Thermitase--a thermostable serine protease. IV. Kinetic studies on the binding of N-acyl peptide ketones as substrate analog inhibitors].

Peptide methyl ketones were found to be efficient competitive inhibitors of thermitase while the chloromethyl ketone derivatives in general inhibit the enzyme irreversibly. The affinity increases by elongation of the peptide chain up to four residues indicating an interaction of the ligand with an extended binding site in thermitase. The P1 residue is phenylalanine in most of the inhibitors, according to the substrate specificity of thermitase for phenylalanine and other hydrophobic amino acids. Peptide ketones protected with the hydrophobic bencyloxycarbonyl group at the N-terminus are bound to the enzyme more tightly than the corresponding acetyl compounds. As reversible inhibitors peptide methyl ketones form a tetrahedral hemiketale with the oxygen of the active serine. In the case of the chloromethyl ketones this complex is stabilized by covalent binding to histidine-64. The inductive effect of the halogen favours the formation of the hemiketale and is expressed in about twenty times lower inhibition constants of the chloromethyl ketones. Results of the kinetic experiments show a corresponding behaviour in effector binding by thermitase and subtilisin in the S region, and from this point of view also indicate a high similarity of the active centers of both enzymes.

Actinomycetales↗