Table 1.

Site-selective ¹³C incorporation in aromatic side-chains using glucose (G) or erythrose (E)

	1-13C G	2-13C G	1-13C E	2-13C E	3-13C E	4-13C E
Phe γ	6	55	2	4	24	0
Phe δ*	34	4	1	2	1	41
Phe ε*	2	22	20	4	23	1
Phe ζ	1	1	5	39	1	1
Tyr γ	n.d	n.d	n.d	n.d	n.d	n.d
Tyr δ*	32	4	2	2	1	45
Tyr ε*	1	19	17	3	23	1
Tyr ζ	0	0	7	48	11	5
Trp γ	9	10	1	3	0	1
Trp δ1	26	49	4	3	2	2
Trp δ2	n.d	n.d	n.d	n.d	n.d	n.d
Trp ε2	n.d	n.d	n.d	n.d	n.d	n.d
Trp ε3	26	2	1	2	1	54
Trp ζ3	1	24	1	1	52	1
Trp η2	1	2	6	35	1	0
Trp ζ2	2	12	27	5	0	1

Values are in %. Errors are estimated to 1% for ¹H bound ¹³C, 3% for others. 1% for non labeled positions is expected because of natural abundance of ¹³C

*Represents an averaged signal of position 1 and 2 because of fast exchange of the aromatic rings on the NMR time-scale