Pyrene-sensitised near-IR luminescence from ytterbium and neodymium complexes.

Ytterbium and neodymium have been shown to exhibit sensitised emission following excitation of pyrene chromophores. Sensitised emission is demonstrated in self-assembled complexes and in azamacrocycle derivatives bearing pendent pyrene groups. Energy transfer in these systems is dependent on the nature of the link between the ligand and the complex.

Steric acceleration of an uncatalysed ene reaction at room temperature.

The bulky trityl steric buttress is used to effect an intramolecular, uncatalysed ene reaction that operates at room temperature, whilst smaller buttresses require heat.

Kinetics of inactivation of beta-lactamase I by 6 beta-bromopenicillanic acid.

The kinetics of the inactivation of beta-lactamase I from Bacillus cereus 569 by preparations of 6 alpha-bromopenicillanic acid showed unexpected features. These can be quantitatively accounted for on the basis of the inactivator being the epimer, 6 beta-bromopenicillanic acid. At pH 9.

Active sites of beta-lactamases from Bacillus cereus.

There are two extracellular beta-lactamases produced by Bacillus cereus 569. One of these enzymes, beta-lactamase I, is inactivated by 6-beta-bromopenicillanic acid: the site of reaction is serine-44. This is a conserved amino acid residue in the other beta-lactamases whose structures have been determined, and it becomes a good candidate for an active-site group in these enzymes.