Structures of an isopenicillin N converting Ntn-hydrolase reveal different catalytic roles for the active site residues of precursor and mature enzyme.

Penicillium chrysogenum Acyl coenzyme A:isopenicillin N acyltransferase (AT) performs the last step in the biosynthesis of hydrophobic penicillins, exchanging the hydrophilic side chain of a precursor for various hydrophobic side chains. Like other N-terminal nucleophile hydrolases AT is produced as an inactive precursor that matures upon posttranslational cleavage. The structure of a Cys103Ala precursor mutant shows that maturation is autoproteolytic, initiated by Cys103 cleaving its preceding peptide bond.

Serum- and animal tissue-free medium for transport and growth of Helicobacter pylori.

The important human gastric pathogen Helicobacter pylori is the subject of many studies, and as a consequence it is frequently being transported between national and international laboratories. Unfortunately, common bacterial growth and transport media contain serum- and animal tissue-derived materials, which carry the risk of spreading infectious diseases. We have therefore developed a growth and transport medium for H.

An approach to prevent aggregation during the purification and crystallization of wild type acyl coenzyme A: isopenicillin N acyltransferase from Penicillium chrysogenum.

Acyl coenzyme A: isopenicillin N acyltransferase (AT) from Penicillium chrysogenum is an enzyme of interest for the biosynthesis of beta-lactam antibiotics. Severe aggregation problems with wild type AT have, however, prevented significant progress in the structure-function analysis of this enzyme for a decade. In this study, we show an approach to solve this aggregation problem by using dynamic light scattering (DLS) analysis to probe the aggregation state of the protein in the presence of various additives.

Bovine antibody-enriched whey to aid in the prevention of a relapse of Clostridium difficile-associated diarrhoea: preclinical and preliminary clinical data.

In a pilot study, the feasibility of immune whey protein concentrate (40%; immune WPC-40) to aid the prevention of relapse of Clostridium difficile diarrhoea was evaluated. Immune WPC-40 was made from milk after immunization of Holstein-Frisian cows with C. difficile-inactivated toxins and killed whole-cell C.

Structural and kinetic studies on ligand binding in wild-type and active-site mutants of penicillin acylase.

Penicillin acylase catalyses the condensation of Calpha-substituted phenylacetic acids with beta-lactam nucleophiles, producing semi-synthetic beta-lactam antibiotics. For efficient synthesis a low affinity for phenylacetic acid and a high affinity for Calpha-substituted phenylacetic acid derivatives is desirable. We made three active site mutants, alphaF146Y, betaF24A and alphaF146Y/betaF24A, which all had a 2- to 10-fold higher affinity for Calpha-substituted compounds than wild-type enzyme.