Table 2. Hydrogen bonds between holoenzyme and precorrin-6B.

Pyrrole ring	Carboxylate	Hydrogen bonds
A	Acetate	(O28) Hydrogen bonds to main chain amide of Lys196 and carbonyl of Ala133 via bound water molecule(O29) Hydrogen bonds to NZ Lys206 and carbonyl of Lys196 via bound water molecule
	Propionate	(O33) Hydrogen bonds to NH1 Arg153, NZ of Lys206 and bound water (water also hydrogen bonds to OD2 Asp181 and NH Lysine 206)(O34) Hydrogen bonds to both NE Arg153
B	Acetate	(O39) Hydrogen bonds to main chain amide of Thr11 and bound water(O40) No clear hydrogen bonding
	Propionate	(O44) Hydrogen bonds to OG1 of Thr11(O45) Hydrogen bonds to OG of Ser14 and bound water
C	Acetate	(O22) Hydrogen bonds to NH2 of Arg173 and OG1 of Thr35(O23) Hydrogen bonds to NE of Arg173
	Propionate	(O51) Hydrogen bonds main chain amides Ala32 and Arg34.(O52) Hydrogen bonds main chain amide of Ala32 and O3’ of nicotinamide ribose ring NADPH
D	Propionate	(O58) Hydrogen bonds to NZ Lys136 and water(O59) Main chain amide of Val55 and water
	Acetate	(O62) Hydrogen bonds to NZ of Lys196, NH2 of Gln137 and a bound water(O63) Hydrogen bonds to main chain amides of Lys136 and Gln137

Hydrogen-bonds involving conserved basic residues are underlined.