Table 1.

13C CP/MAS NMR chemical shifts of the sequential model peptides and B. mori silk fibroins in the silk II forms (ppm from TMS)

	G(AG)3	(AG)9	(AG)12	(AG)15	Cpa	(AGSGAG)5	Silk fiber	(AG)3Y1Vb
Gly Cα	42.3	42.3	42.4	42.4	42.5	42.6	42.5	42.6
C=O	167.4
	169.1	169.0	169.0	169.1	169.2	169.5	169.3	169.5
Ala Cα	48.6	48.7	48.6	48.7	48.8	48.9	48.9	48.8
Cβ		16.6	16.5	16.7	16.5	16.7	16.7	16.5
	20.6	19.2	19.5	19.6	19.5	19.9	19.9	21.1
	22.5	22.3	22.4	22.2	22.1	22.1	22.1
C=Oc	171.8	171.9	171.8	171.8	172.0	172.1	172.2	172.2
Ser Cα	—	—	—	—	54.9	55.0	54.6	—
Cβ	—	—	—	—	63.8	63.9	63.9	—

^a Precipitated fraction after chymotrypsin cleavage of B. mori silk fibroin.

^b (AG)3Y1V means the peptide, (AG)₃YG(AG)₂VGYG(AG)₃YG(AG)₃.

^c The Ser carbonyl peak was superimposed with the Ala carbonyl peak.