NDLI: Enzymatic Properties of the Sweet-Tasting Proteins Thaumatin and Monellin after Partial Reduction

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Enzymatic Properties of the Sweet-Tasting Proteins Thaumatin and Monellin after Partial Reduction

Content Provider	Scilit
Author	Wel, H. Van Der Bel, Wim J.
Copyright Year	1980
Description	Journal: Journal of Biological Inorganic Chemistry After partial reduction of disulfide bonds in the thaumatins, the sweet-tasting proteins from the fruits of Thaumatococcus danielii Benth, a rapid autodigestion was demonstrated. In the presence of suitable substrates, the reduced thaumatins showed protease, amidase and esterase activity. Thiol-blocking reagents like mercury(II) chloride inhibited the enzymatic activity. Of the thaumatins b, c, I, II and III (with increasing isoelectric points), thaumatin I showed the lowest enzymatic activity. In this series, the enzymatic activity increased from thaumatin I to thaumatin III as well as from thaumatin I to thaumatin b. Acetylation of the epsilon-amino group of lysine residues in the thaumatins by acetic anhydride, causing a decrease in basicity, led to an increase in enzymatic activity, which is correlated with the number of acetyl groups introduced. Comparison of the amino acid sequence of thaumatin I with that of cysteine proteases of plant origin showed no similarities. Moreover, the thaumatins lack histidine, one of the amino acids in the active site of the cysteine proteases. Monellin, the sweet-tasting protein from the fruits of Dioscoreophyllum cumminsii Diels, is not enzymatically active. However, when monellin with acetylated epsilon-amino groups of lysine residues was brought into a reducing environment it appeared to be enzymatically active. The similarities in properties of the thaumatins and monellin suggest a structural relationship between these proteins.
Related Links	http://onlinelibrary.wiley.com/doi/10.1111/j.1432-1033.1980.tb04442.x/pdf
Ending Page	418
Page Count	6
Starting Page	413
ISSN	09498257
e-ISSN	14321327
DOI	10.1111/j.1432-1033.1980.tb04442.x
Journal	Journal of Biological Inorganic Chemistry
Issue Number	2
Volume Number	104
Language	English
Publisher	Wiley-Blackwell
Publisher Date	1980-03-01
Access Restriction	Open
Subject Keyword	Journal: Journal of Biological Inorganic Chemistry Paper and Wood Enzymatic Properties Tasting Proteins Sweet Tasting
Content Type	Text
Resource Type	Article
Subject	Biochemistry Inorganic Chemistry

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