A cost-effective approach to produce 15N-labelled amino acids employing Chlamydomonas reinhardtii CC503

Table 3 Isotopic enrichment for the detected amino acids

Amino acid	Fragment formula	¹⁵N isotopic enrichment (%)	Concentration ± s.d. (ppm)
Alanine	C₁₁H₂₆ ¹⁵NO₂Si₂	99.68	70.50 ± 0.23
Glycine	C₁₀H₂₄ ¹⁵NO₂Si₂	99.50	45.68 ± 0.43
Valine	C₁₄H₃₂ ¹⁵NO₂Si₂	99.56	52.38 ± 0.17
Leucine	C₁₄H₃₂ ¹⁵NO₂Si₂	99.56	78.27 ± 0.12
Isoleucine	C₁₄H₃₂ ¹⁵NO₂Si₂	99.52	35.24 ± 0.10
Proline	C₁₃H₂₈ ¹⁵NO₂Si₂	99.54	44.44 ± 3.56
Methionine	C₁₃H₃₀ ¹⁵NO₂SSi₂	99.59	21.86 ± 0.02
Serine	C₁₇H₄₀ ¹⁵NO₃Si₃	99.49	34.49 ± 0.04
Threonine	C₁₈H₄₂ ¹⁵NO₃Si₃	99.54	41.06 ± 0.60
Phenylalanine	C₁₇H₃₀ ¹⁵NO₂Si₂	99.58	45.07 ± 0.12
Aspartic acid	C₁₈H₄₀ ¹⁵NO₄Si₃	99.51	77.98 ± 0.07
Glutamic acid	C₁₉H₄₂ ¹⁵NO₄Si₃	99.56	90.78 ± 0.12
Arginine	C₁₀H₂₂ ¹⁵NSi	99.60	57.32 ± 0.79
Lysine	C₂₀H₄₇ ¹⁵N₂O₂Si₃	99.54	52.69 ± 1.39
Histidine	C₂₀H₄₂ ¹⁵N₃O₂Si₃	99.56	18.48 ± 0.06
Tyrosine	C₂₃H₄₄ ¹⁵NO₃Si₃	99.64	34.14 ± 0.17

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