Kinetics of inhibition of ribonuclease A by Pholiota Nameko polysaccharide

Pholiota nameko polysaccharide (PNPS-1) has been isolated and purified by enzyme hydrolysis, hot water extraction, ethanol precipitation, ion-exchange chromatography and gel-filtration column chromatography. The inhibition of bovine pancreas ribonuclease (RNase A) by PNPS-1 has been studied to elucidate the mechanism responsible for the decreased activity. PNPS-1 was effective in a linear mixed-type inhibition as suggested from the Lineweaver–Burk plot, Dixon plot and their replots. The values of Ki and αKi were estimated as 299.92 and 545.71 μM, respectively. The αKi was greater than Ki indicating that noncompetitive inhibition was predominant over competitive inhibition.