The competitive inhibition of Trichoderma reesei C30 cellobiohydrolase I by guanidine hydrochloride

FEBS Letters

Herrmann, Paul C.¹  Carmichael, Jeffrey S.¹  Lee, Norman E.¹  Capps, Katherine M.¹  Woodward, Jonathan¹ 

[1] Chemical Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6194, USA

关键词: Cellulase;    Cellobiohydrolase I;    Trichoderma reesei;    Guanidine hydrochloride;    Inhibition;    Hydrolase;    Protease;   

DOI  :  10.1016/0014-5793(90)81254-L

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

TheP-nitrophenylcellobiosidase (PNPCase) activity of Trichoderma reesei cellobiohydrolase I (CBH I) was competitively inhibited by concentrations of guanidine hydrochloride (Gdn HC1) that did not affect the tryptophan fluorescence of this enzyme. The K _m of CBH I, 3.6 mM, was increased to 45.4 mM in the presence of 0.14 M Gdn HCl, the concentration that was required to inhibit the enzyme by 50%. A similar concentration of lithium chloride and urea had little effect on the PNPCase activity of CBH I. Maximal inhibition was pH dependent, occurring in the range of pH 4.0 to 5.0, which is in the range for maximal activity. Analysis of the inhibition data indicated that 1.2 molecules of Gdn HCl combine reversibly with I molecule of CBH I. Other hydrolases and proteases were also inhibited by Gdn HCl. It is suggested that the inhibition of CBH I by Gdn HCl occurs as a result of the interaction between the positively charged guanidinium group of Gdn HCl and the carboxylate group of glutamic acid 126, postulated to be in the catalytic center of this enzyme.

【 授权许可】

Unknown