Screening of traditional Chinese medicine monomers as ribonucleotide reductase M2 inhibitors for tumor treatment

Table 3 The binding energy and binding sites of the selected traditional Chinese medicine monomers with ribonucleotide reductase M2

Names	Binding energy	Hydrogen bond site	Hydrophobic bond site
Berberine	-7.3 kcal/mol	Ser263 (A)	Glu260(A), Arg264(A), Tyr323(A), Arg330(A), Gly233(A), Val327(A), Ser237(A), and Gly267(A)
Ursolic acid	-8.6 kcal/mol	-	Arg264(A), Gly267(A), Cys270(A), Gly233(A), Arg330(A), Val327(A), Ser263(A), Phe244(A), Phe349(A), and Met350(A)
Gambogic acid	-8.6 kcal/mol	Arg330(A) and Tyr323(A)	Gly267(A), Leu268(A), Ser100(A), Lys96(A), Arg264(A), Met350(A), and Ser263(A)
Cinobufagin	-7.6 kcal/mol	Asp271 (A) and Arg330 (A)	Glu334 (A), Leu331 (A), Cys270 (A), Gly267 (A), Glu266 (A), Ser263 (A), Phe244 (A), and Met350 (A)
Quercetin	-7.4 kcal/mol	Arg330 (A) and Tyr323 (A)	Met350 (A), Arg264 (A), Glu260 (A), Phe244 (A), Ser263 (A), Glu232 (A), Gly233 (A), Phe240 (A) and Val327 (A)
Daphnetin	-6.7 kcal/mol	Tyr323 (A) and Arg330 (A)	Val327 (A), Ser263 (A), Phe240 (A), Met350 (A), Gly267 (A), Gly233 (A), and Gys270 (A)
Osalmide	-6.8 kcal/mol	-	Phe244 (A), Arg264 (A), Tyr323 (A), Phe240 (A), Ser237 (A), Met350 (A), Gly233 (A), and Ser263 (A)