The synthesis of N-(p-nitrocarbobenzoxy)glutathione (N-pNCBG) is reported. N-pNCBG and glutathione (GSH) were coupled to Affi-gel 10 by a thioester linkage and resulted in very effective bound ligands for a fast purification of glyoxalase II from corn. The S-(N-pNCBG)-affinity column showed a glyoxalase II binding capacity of up to 2-fold higher than that of the glutathione-affinity column. A single form of glyoxalase II was evidenced by PAGE in both crude extracts and in the affinity purified enzyme. A 45% recovery of glyoxalase II activity (purification, approx. 433-fold) was obtained for both matrices by a single chromatography. The purified glyoxalase is an acidic protein (pI 4.5) of about 26,000 relative molecular mass. Substrate studies for the corn glyoxalase II show, among possible substrates tested, that S-D-lactyl-glutathione is the preferred substrate. An inhibition study was performed with methyl-, propyl-, hexyl-, p-nitrobenzyl-, p-chlorophenacyl-, carbobenzoxy-, and p-nitrocarbobenzoxy- S-glutathione. Methyl-S-glutathione did not inhibit corn glyoxalase II; the others were found to be linear competitive inhibitors. The derivatives containing a thioether bond are weaker inhibitors than those containing a thioester bond or a carbonyl group. p-Nitrobenzyl- S-glutathione is the weakest inhibitor; the carbobenzoxy-S-derivatives are stronger inhibitors than the p-chlorophenacyl S-derivative.

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The faba bean is a legume primarily used in animal feeding as grain and, to a lesser degree, as fodder. As noted, grain, being a good source of amylacea (starch) (45–50% DM) and protein (23–30 CP%DM) of discrete biological value (Verite and Peyraud, 1988), acts as an alternative to soybean which is particularly suitable for organic breeding. Despite this, low productive yields and the presence of thermostable antinutritional factors have reduced the diffusion of this legume especially in feeding non-ruminant species. The objective of the current work was that of investigating the effect of the genotype and conditions (time and place of sowing) on the amount in polyphenols, vicine, convicine and phytates of five varieties of faba bean (Vicia faba var. minor) that have recorded the best protein yields under Umbrian pedoclimatic conditions (Monotti et al., 2004; Mannino, 2003)