Physical and biological properties of the fungal cell wall are determined by the composition and arrangement of the structural polysaccharides. Cell wall polymers of fungi are classically divided into two groups depending on their solubility in hot alkali. We have analyzed the alkali-insoluble fraction of the Aspergillus fumigatus cell wall, which is the fraction believed to be responsible for fungal cell wall rigidity. Using enzymatic digestions with recombinant endo-β-1,3-glucanase and chitinase, fractionation by gel filtration, affinity chromatography with immobilized lectins, and high performance liquid chromatography, several fractions that contained specific interpolysaccharide covalent linkages were isolated. Unique features of the A. fumigatuscell wall are (i) the absence of β-1,6-glucan and (ii) the presence of a linear β-1,3/1,4-glucan, never previously described in fungi. Galactomannan, chitin, and β-1,3-glucan were also found in the alkali-insoluble fraction. The β-1,3-glucan is a branched polymer with 4% of β-1,6 branch points. Chitin, galactomannan, and the linear β-1,3/1,4-glucan were covalently linked to the nonreducing end of β-1,3-glucan side chains. As in Saccharomyces cerevisiae, chitin was linked via a β-1,4 linkage to β-1,3-glucan. The data obtained suggested that the branching of β-1,3-glucan is an early event in the construction of the cell wall, resulting in an increase of potential acceptor sites for chitin, galactomannan, and the linear β-1,3/1,4-glucan.

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6
3,3,3,3,3,3,3,3,3	b?Glc?	105.6	76.1	78.3	72.3	78.3	63.3
3,3,3,3,3,3,3,3	b?Glc?
3,3,3,3,3,3,3	b?Glc?
3,3,3,3,3,3	b?Glc?
3,3,3,3,3	b?Glc?
3,3,3,3	b?Glc?
3,3,3,6,3,4,2	Ac
3,3,3,6,3,4	b?Glc?N	104.2	58.3	76.2	72.4	78.5	63.3
3,3,3,6,3	b?Glc?	105.2	75.8	77.0	82.0	77.3	62.7
3,3,3,6	b?Glc?	105.3	75.6	86.9	70.8	78.2	63.4
3,3,3	b?Glc?
3,3	b?Glc?
3	b?Glc?
	b?Glc?	?	?	?	71.4	76.1	63.6


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6
3,3,3,3,3,3,3,3,3	b?Glc?	4.75	3.36	3.53	3.41	3.48	3.73-3.92
3,3,3,3,3,3,3,3	b?Glc?
3,3,3,3,3,3,3	b?Glc?
3,3,3,3,3,3	b?Glc?
3,3,3,3,3	b?Glc?
3,3,3,3	b?Glc?
3,3,3,6,3,4,2	Ac
3,3,3,6,3,4	b?Glc?N	4.57	3.74	3.57	3.47	3.52	3.75-3.93
3,3,3,6,3	b?Glc?	4.77	3.38	3.68	3.58	3.57	3.65-3.84
3,3,3,6	b?Glc?	4.52	3.52	3.76	3.50	3.52	3.75-3.92
3,3,3	b?Glc?
3,3	b?Glc?
3	b?Glc?
	b?Glc?	?	?	?	3.87	3.79	3.74-4.09


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6
3,3,3,3,3,3,3,3,3	b?Glc?	105.6/4.75	76.1/3.36	78.3/3.53	72.3/3.41	78.3/3.48	63.3/3.73-3.92
3,3,3,3,3,3,3,3	b?Glc?
3,3,3,3,3,3,3	b?Glc?
3,3,3,3,3,3	b?Glc?
3,3,3,3,3	b?Glc?
3,3,3,3	b?Glc?
3,3,3,6,3,4,2	Ac
3,3,3,6,3,4	b?Glc?N	104.2/4.57	58.3/3.74	76.2/3.57	72.4/3.47	78.5/3.52	63.3/3.75-3.93
3,3,3,6,3	b?Glc?	105.2/4.77	75.8/3.38	77.0/3.68	82.0/3.58	77.3/3.57	62.7/3.65-3.84
3,3,3,6	b?Glc?	105.3/4.52	75.6/3.52	86.9/3.76	70.8/3.50	78.2/3.52	63.4/3.75-3.92
3,3,3	b?Glc?
3,3	b?Glc?
3	b?Glc?
	b?Glc?	?/?	?/?	?/?	71.4/3.87	76.1/3.79	63.6/3.74-4.09

The spectrum also has 3 signals at unknown positions (not plotted).

There are too many chemically distinct structures (~67108864), so only one is shown:

bDGlcp(1-3)bDGlcp(1-3)bDGlcp(1-3)bDGlcp(1-3)bDGlcp(1-3)bDGlcp(1-3)[Ac(1-2)bDGlcpN(1-4)bDGlcp(1-3)bDGlcp(1-6)]bDGlcp(1-3)bDGlcp(1-3)bDGlcp(1-3)bDGlcp

SVGMWSMILES3D molIonize

 

CC(=O)N[C@H]1[C@H](O[C@@H]2[C@@H](CO)O[C@@H](O[C@H]3[C@H](O)[C@@H](CO)O[C@@H](OC[C@H]4O[C@@H](O[C@@H]5[C@@H](O)[C@H](O[C@@H]6[C@@H](O)[C@H](O[C@@H]7[C@@H](O)[C@H](O)O[C@H](CO)[C@H]7O)O[C@H](CO)[C@H]6O)O[C@H](CO)[C@H]5O)[C@H](O)[C@@H](O[C@@H]5O[C@H](CO)[C@@H](O)[C@H](O[C@@H]6O[C@H](CO)[C@@H](O)[C@H](O[C@@H]7O[C@H](CO)[C@@H](O)[C@H](O[C@@H]8O[C@H](CO)[C@@H](O)[C@H](O[C@@H]9O[C@H](CO)[C@@H](O)[C@H](O[C@@H]%10O[C@H](CO)[C@@H](O)[C@H](O)[C@H]%10O)[C@H]9O)[C@H]8O)[C@H]7O)[C@H]6O)[C@H]5O)[C@@H]4O)[C@@H]3O)[C@H](O)[C@H]2O)O[C@H](CO)[C@@H](O)[C@@H]1O

2166.901 g/mol (C₈₀H₁₃₅NO₆₆)