Labelling experiments are described that identify three new compounds, N2-(2-carboxyethyl)arginine, 5-guanidino-(2-oxoazetidin-1-yl)pentanoic acid, and 3-hydroxy-5-guanidino-2-(2-oxoazetidin-1-yl)pentanoic acid as biosynthetic precursors of proclavaminic acid and hence clavulanic acid in Streptomyces clavuligerus TCC 27064 and a new amidino hydrolase, which hydrolyses 3-hydroxy-5-guanidino-2-(2-oxoazetidin-1-yl)pentanoic acid to proclavaminic acid has been characterised.

AbstractMoving belt LC/MS has been used to identify the degradation products of the slow calcium membrane channel inhibitor, Diproteverine, after storage at elevated temperature and humidity. The major products observed result from oxidation. Two of these products, both ketones, yield [M  14 + H]+ ions by chemical ionization. These unusual ions also occur for some simple aromatic ketones used as model compounds and are shown to arise by reduction of the carbonyl group to a methylene by the reagent gas.