New concepts in the evaluation of biodegradation/persistence of chemical substances using a microbial inoculum.

The European REACH Regulation (Registration, Evaluation, Authorization of CHemical substances) implies, among other things, the evaluation of the biodegradability of chemical substances produced by industry. A large set of test methods is available including detailed information on the appropriate conditions for testing. However, the inoculum used for these tests constitutes a "black box.

Improving ready biodegradability testing of fatty amine derivatives.

This study assesses the biodegradation potential of a number of fatty amine derivatives in tests following the OECD guidelines for ready biodegradability. A number of methods are used to reduce toxicity and improve the bioavailability of the fatty amine derivatives in these tests. Alkyl-1,3-diaminopropanes and octadecyltrimethylammonium chloride are toxic to microorganisms at concentrations used in OECD ready biodegradability tests.

Purification, characterisation, and gene cloning of transglutaminase from Streptoverticillium cinnamoneum CBS 683.68.

The transglutaminase (TGase; EC 2.3.2.

Rat platelet phospholipase A2. Kinetic characterization using the monomolecular film technique.

We have determined some kinetic parameters of rat platelet phospholipase A2, such as surface pressure dependency and substrate specificity, using the monomolecular film technique. We found that rat platelet phospholipase A2 is very specific for phospholipids having a negatively charged headgroup, no activity was detected when using zwitterionic phospholipids such as phosphatidylcholine. Furthermore, the interfacial pressure window which permits enzyme activity is very narrow as compared to pancreatic phospholipase A2.

Competitive inhibition of lipolytic enzymes. V. A monolayer study using enantiomeric acylamino analogues of phospholipids as potent competitive inhibitors of porcine pancreatic phospholipase A2.

For the first time, we have shown that a stereospecific interaction occurs between porcine pancreatic phospholipase A2 and a monomolecular film of amidophospholipid used as inhibitor. Direct binding experiments, using radiolabelled phospholipase A2, showed that 13 times more enzyme was bound to phospholipid films of the L series by comparison with films of the D series. These results were confirmed by indirect binding studies using re-spreading experiments.

Competitive inhibition of lipolytic enzymes. I. A kinetic model applicable to water-insoluble competitive inhibitors.

It is now becoming clear from the abundant lipolytic enzyme literature that any meaningful interpretation of inhibition data has to take into account the kinetics of enzyme action at the lipid/water interface. We attempt in the present paper to provide a kinetic model applicable to water-insoluble competitive inhibitors, in order to quantitatively compare the results obtained at several laboratories. We derived kinetic equations applicable to the pre-steady state as well as steady state.