Table II.

Isotopomer analysis of multiple ¹³C-labeled IAA and amino acids isolated from developing maize kernels supplied with [U-¹³C₆]Glc

Compound	A	B	C	D	E
IAA	1′,2′-13C2	1	0.54	0.22	0.39
	2,3-13C2	2	1.00	0.40	0.70
	3a,7a-13C2	3	1.48	0.59	1.05
Trp	1′,2′-13C2	w1	0.30	0.14	0.29
	2′,3′-13C2	w2	0.13	0.06	0.12
	1′,2′,3′-13C3	w3	0.36	0.17	0.35
	2,3-13C2	w4	0.64	0.30	0.62
	3a,7a-13C2	w5	0.98	0.64	0.95
His	1,2-13C2	h3	0.26	0.10	0.17
	1,2,3-13C3	h2	1.00	0.39	0.68
	4,5-13C2	h1	0.90	0.35	0.61
Leu	1,2-13C2	l1	1.01	0.47	0.97
Tyr	2,3-13C2	y1	0.32	0.12	0.21
	1,2,3-13C3	y2	1.05	0.40	0.68

A, Isotopomers analyzed. B, Abbreviation for the analyzed isotopomer (see Fig. 4). C, mol % of isotopomer carrying ¹³C nuclei at least at the designated positions. D, Fraction of multiple ¹³C-labeled isotopomers of all isotopomers carrying ¹³C at the designated positions (see “Materials and Methods”). E, Fraction of multiple ¹³C-labeled isotopomers of all isotopomers carrying ¹³C at the designated positions incorporated during the labeling (see “Materials and Methods”). This normalization enables comparison of metabolites with different de novo biosynthetic rate using ¹³C-enrichment data: IAA, 2.50% ¹³C; Trp, 2.14% ¹³C; Leu, 2.14% ¹³C; Tyr, 2.63% ¹³C; His, 2.57% ¹³C.