X-ray sequence and crystal structure of luffaculin 1, a novel type 1 ribosome-inactivating protein

BMC Structural Biology

Table 2 Assignment of the sequence of luffaculin 1 by X-ray sequencing method (total number of residues: 241)

	Sequence assignment method	Number of identified residues
1	Both molecule A and B have clear electron density and can be assigned unambiguously	151
2	Using method 1 plus electron density of the second molecule for those residues where the first molecule has weak electron density, 66% of residues (160) can be deduced	160 (9 additional residues were assigned: A123, A185, A206, A215, A219, A221, A222, A234 and B209)
3	Using methods 1 and 2 plus chemical environment evaluation without using sequence comparison, 86% of residues (208) can be deduced.	208 (exclude 28, 29, 33, 48, 56, 93, 97, 109, 111, 122, 132, 142, 156, 157, 169, 177,179, 190, 197, 202, 204, 205, 213, 216, 217, 218, 220, 223, 225, 226, 228, 237, 241)
4	Using method 3 plus the sequence comparison, 94% of residues (227) can be deduced.	227 (exclude 28, 29, 97, 109, 111, 190, 216, 217, 218, 220, 225, 228, 223, 237)
	Neither molecule A nor B has clear density map, but the sequence is highly conserved among RIPs	4 (A&B109, A&B179, A&B111, A&B223*)
	Neither molecule A nor B has clear density map, and the sequence is not conserved among RIPs	6 (A&B29, A&B97, A&B217, A&B218, A&B225, A&B228)

*These residues belong to residue pairs (Asn/Asp, Gln/Glu, Val/Thr) and cannot be distinguished by X-ray crystallography.
**These two residues are conserved, but the electron density of both molecules A and B isn't clear, so we cannot classify these two residues to Group 4.

ISSN: 1472-6807