Table 2.
Some Physical Parameters of Crystalline “Sialic Acids” Isolated From Bovine, Porcine, Ovine, and Equine Submaxillary Gland Mucins23
| Mucin Source | Elemental Analysisa | [α]20D (5%, H2O) | Decomposition Range (°C) | N,O-Acyl Groupsb | Hydroxy Groups |
|---|---|---|---|---|---|
| Bovinec | C13H21NO10 | + 8° ± 2° | 134–137 | NAc, OAc | n.a. |
| Ovine | C11H19NO9 | − 31° ± 2° | 185–187 | NAc | 5 |
| Porcine | C11H19NO10 | − 32° ± 2° | 185–187 | NGc | 6 |
| Equinec | C13H21NO10 | − 59° ± 2° | 183–187 | NAc, OAc | n.a. |
n.a., not available.
a
Note that in earlier reports it was not realized that during crystallization protocols, wherein methanol was used, partial methyl ester formation took place (all preparations contained one COOH function). The included chemical formulae from this study turned out to be in the end correct.
b
NAc = N-acetyl; OAc = O-acetyl; NGc = N-glycolyl. Acetyl determination as barium acetate after acid hydrolysis; glycolyl determination as crystalline calcium glycolate after alkaline treatment (see Section 7.1).
c
The bovine and equine “sialic acids” were suggested to be isomers.