Modification of jack bean urease thiols by thiosulphinates contained in garlic extract: DTNB titration studies

Jack bean urease inhibition by crude juices of Allium and Brassica plants. Determination of thiosulfinates

“…The Brassica species contain only methiin, which is converted into methylmethanethiosulfinate and then to dimethylthiosulfonate, dimethylsulfide and polymethylsulfides (Kyung & Lee, 2001;Rose et al, 2005). The inhibition of jack bean urease by garlic extract has already been investigated by our staff (Juszkiewicz, Zaborska, Sepioł, Góra, & Zaborska, 2003;Juszkiewicz, Zaborska, Łaptaś, & Olech, 2004;Zaborska, Karcz, Kot, & Juszkiewicz, 2009). It has been found that allicin the most abundant TS present in fresh garlic extract is responsible for inhibition of the enzyme.…”

Effect of thiosulphinates contained in garlic extract on growth, proton fluxes and membrane potential in maize (Zea mays L.) coleoptile segments

“…The mechanisms by which allicin may contribute to biological control of molecular processes are largely unknown although a number of studies showing toxic activity of allicin driven by its action on free thiol groups have been carried out (Wills 1956;Feldberg et al 1988;Focke et al 1990;Ankri et al 1997;Rabinkov et al 1998;Juszkiewicz et al 2004). We have also recently shown (Zaborska et al 2009) that TSs contained in GE act as time-and concentration-dependent inactivators of jack bean urease. Interestingly, the modification of half of all the urease thiols (18 of 36) caused a slight (only 8-10%) decrease of the catalytic activity, while the modification of the remaining 18 thiols resulted in significant disturbance of urease action until complete loss of the catalytic function occurred.…”

“…12); (2) abolishing the first peak in the biphasic kinetics of IAA-induced growth (Fig. 3); (3) literature data showing inhibition of various enzymes by allicin (Wills 1956;Feldberg et al 1988;Focke et al 1990;Ankri et al 1997;Rabinkov et al 1998;Juszkiewicz et al 2004;Zaborska et al 2009). The third mechanism, observed here as a gradual decrease of medium pH following its a maximal value, is probably connected with concentration-and time-dependent partial reversibility of thiol-disulfide exchange reaction.…”

“…Next, the homogenate was shaken for 20 min and filtered through gauze. Undissolved material was removed by centrifugation at 300 g for 4 min, as previously described (Juszkiewicz et al 2004;Zaborska et al 2009). The method of Han et al (1995) was used to quantify the amount of thiosulphinates contained in GE.…”

“…To date, allicin is the best characterized biologically active compound of GE. Allicin undergoes thiol-disulfide exchange reactions and can react with SH-containing enzymes, causing their inhibition (Wills 1956;Feldberg et al 1988;Focke et al 1990;Ankri et al 1997;Rabinkov et al 1998;Juszkiewicz et al 2004;Zaborska et al 2009). At present, a variety of biological effects of allicin is attributed not only to its high reactivity with SH-containing molecules, but also to its antioxidant activity and its high permeability through membranes (Prasad et al 1995;Rabinkov et al 1998;Miron et al 2000;Pedraza-Chaverri et al 2006).…”