Phenylboronic Acida Potent Inhibitor of Lipase from Oryza sativa

Abstract

The kinetics of inhibition of rice bran lipase (RBL) by phenylboronic acid (PBA) was studied to elucidate the nature of inhibition and the effect of the inhibitor on the structure-function of RBL. The effectiveness of an inhibitor is normally expressed by the constant K(i), which is calculated from the Lineweaver-Burk plot and found to be 1.7 mM at pH 7.4. The kinetics of inhibition by PBA was competitive, indicating the presence of serine in the active site of the enzyme. The loss of activity of RBL was concentration dependent on the inhibitor (PBA), and the inactivation followed a pseudo-first-order kinetics. Fluorescence emission measurements indicated a decrease in the fluorescence emission intensity and a red shift in the emission maximum as the inhibitor concentration was increased. The inhibition of the enzyme by PBA was also confirmed by thermal denaturation measurements, which indicated a shift in the thermal denaturation temperature of the enzyme toward lower temperatures. The far-UV-CD data suggest that there were no significant changes in the conformation of the enzyme as a result of binding of PBA. These results indicate that PBA is a potential inhibitor of RBL and binds to the enzyme in bringing about inhibition without any structural alterations.

Brown Rice and Its Component, γ-Oryzanol, Attenuate the Preference for High-Fat Diet by Decreasing Hypothalamic Endoplasmic Reticulum Stress in Mice

“…1 E and F ). Previous studies showed that a couple of lipase inhibitors extracted from BR inhibited pancreatic lipase activity, leading to a decrease in intestinal lipid absorption (41–43). Evidence has accrued that lipid accumulation increases ER stress in adipose tissue and liver (44).…”

Mechanism of Inhibition of Rice Bran Lipase by Polyphenols: A Case Study with Chlorogenic Acid and Caffeic Acid

“…Hence one must be cautious in interpreting the molecular weight of proteins. This RBL was extensively studied with reference to the structure–activity relationship in terms of inactivation/stability with various ligands (Rajeshwara and others 1996; Gopalakrishna and others 2002; Raghavendra and Prakash 2002).…”

A DIGESTIVE LIPASE OF Pieris brassicae L. (LEPIDOPTERA: PIERIDAE): PURIFICATION, CHARACTERIZATION, AND HOST PLANTS EFFECTS

“…There are many reports of lipase-inhibitory secondary metabolite compounds in plants (Hatano et al, 1997;Yamamoto et al, 2000;Han et al, 2001;Raghavendra and Prakash, 2002;Shin et al 2004;Ninomiya et al, 2004;Xu et al, 2005;Sheng et al, 2006;Yoshizumi et al, 2006;Karu et al, 2007;Won et al, 2007;Jang et al, 2008;Zhang et al, 2008;Kim et al, 2009;Morikawa et al, 2009;Yamada et al, 2010), based on the inhibition of vertebrate pancreatic lipases, but the mode of action of these chemicals has not been well studied. There are many reports of lipase-inhibitory secondary metabolite compounds in plants (Hatano et al, 1997;Yamamoto et al, 2000;Han et al, 2001;Raghavendra and Prakash, 2002;Shin et al 2004;Ninomiya et al, 2004;Xu et al, 2005;Sheng et al, 2006;Yoshizumi et al, 2006;Karu et al, 2007;Won et al, 2007;Jang et al, 2008;Zhang et al, 2008;Kim et al, 2009;Morikawa et al, 2009;Yamada et al, 2010), based on the inhibition of vertebrate pancreatic lipases, but the mode of action of these chemicals has not been well studied.…”