A serine endopeptidase from cucumber leaves is inhibited by L-arginine, guanidino compounds and divalent cations

Y Yamauchi, T Sugimoto, K Sueyoshi, Y Oji, K Tanaka
Phytochemistry 2001, 58 (5): 677-82
An endopeptidase was purified and characterized from green leaves of cucumber (Cucumis sativus L. suyo). The purified enzyme, a basic amino acid-specific endopeptidase with a pI of 5.0, was a monomeric protein of 80 kDa whose pH optimum was 9.5. Inhibitor analysis suggested that it was a serine endopeptidase and contained sulfhydryl groups essential for catalytic activity. Analysis of internal amino acid sequences of the endopeptidase showed no significant similarity to other proteins. Its activity was inhibited by L-Arg and guanidino compounds having high hydrophobicity, as well as divalent cations such as Mg2+ and Ca2+. The K(i) values of L-Arg and Mg2+, which are also likely in vivo inhibitors, were 3.5 and 10 mM, respectively. Inhibition by L-Arg and Mg2+ was additive, and more than 70% of the activity was reversibly inhibited under their physiologically significant concentrations. These results suggest that the enzyme is possibly regulated by L-Arg and/or guanidino compounds, and by divalent cations in vivo.


You are not logged in. Sign Up or Log In to join the discussion.

Trending Papers

Available on the App Store

Available on the Play Store
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"