The capsular K5 polysaccharide of Escherichia coli is the receptor of the capsule-specific coliphage K5, which harbors an enzyme that degrades the capsular K5 polysaccharide to a number of oligosaccharides. Analysis of the degradation products using gel permeation chromatography, the periodate-thiobarbituric acid and bicinchoninic acid reactions, and nuclear magnetic resonance spectroscopy showed that the major reaction products are hexa-, octa-, and decasaccharides with 4,5-unsaturated glucuronic acid (∆4,5GlcA) at their nonreducing end. Thus, the bacteriophage enzyme is a K5 polysaccharide lyase and not, as we had reported previously, an endo-N-acetylglucosaminidase.

structure, capsular, polysaccharide, analysis, Escherichia, Escherichia coli, capsular polysaccharide, enzymatic, cleavage, elimination, b-elimination

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6
4	bDGlcpA	103.5	74.6	77.3	77.7	77.8	174.2
2	Ac
	aDGlcpN	98.1	54.6	70.5	79.9	72.06	61.0


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6
4	bDGlcpA	4.46	3.39	3.73	3.80	?	-
2	Ac
	aDGlcpN	5.32	3.87	3.75	3.67	3.85	?


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6
4	bDGlcpA	103.5/4.46	74.6/3.39	77.3/3.73	77.7/3.80	77.8/?	
2	Ac
	aDGlcpN	98.1/5.32	54.6/3.87	70.5/3.75	79.9/3.67	72.06/3.85	61.0/?

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

*O[C@@H]1[C@@H](C(=O)O)O[C@@H](O[C@@H]2[C@@H](CO)O[C@H](*)[C@H](NC(C)=O)[C@H]2O)[C@H](O)[C@H]1O

379.318 g/mol (C₁₄H₂₁R₂NO₁₁, R = next and previous repeats, not counted in mol weight)