| 中文名称 | 英文名称 | CAS号 | 化学式 | 分子量 |
|---|---|---|---|---|
| N-乙酰神经氨酸水合物 | sialic acid | 21646-00-4 | C11H19NO9 | 309.273 |
| —— | N-acetyl-4,7,8,9-tetra-O-acetyl-2-chloro-2-deoxyneuraminic acid methyl ester | 67670-69-3 | C20H28ClNO12 | 509.895 |
CBMs (carbohydrate-binding modules) are a class of polypeptides usually associated with carbohydrate-active enzymatic sites. We have characterized a new member of the CBM40 family, coded from a section of the gene NanI from Clostridium perfringens. Glycan arrays revealed its preference towards α(2,3)-linked sialosides, which was confirmed and quantified by calorimetric studies. The CBM40 binds to α(2,3)-sialyl-lactose with a Kd of ∼30 μM, the highest affinity value for this class of proteins. Inspired by lectins' structure and their arrangement as multimeric proteins, we have engineered a dimeric form of the CBM, and using SPR (surface plasmon resonance) we have observed 6–11-fold binding increases due to the avidity affect. The structures of the CBM, resolved by X-ray crystallography, in complex with α(2,3)- or α(2,6)-sialyl-lactose explain its binding specificity and unusually strong binding.