Table 1
Values used to calculate nitrogen-to-protein conversion factors (k A , k P , k)
Amino acid
Abbreviation
Molecular
formula
Avg.
mass
(Da)
Mass
residue
(Da)
Ratio
AAA/AA
(%)
%N in
AA (%)
%N in
AAA (%)
Aspartic acid
Asp
C 4 H 5 NO 3
133.1
115.1
86.50
10.50
12.20
Threonine
Thr
C 4 H 7 NO 2
119.1
101.1
84.90
11.80
13.90
Serine
Ser
C 3 H 5 NO 2
105.1
87.1
82.90
13.30
16.10
Glutamic acid
Glu
C 5 H 7 NO 3
147.1
129.1
87.80
9.50
10.80
Proline
Pro
C 5 H 7 NO
115.1
97.1
84.40
12.20
14.40
Glycine
Gly
C 2 H 3 NO
75.1
57.1
76.00
18.70
24.60
Alanine
Ala
C 3 H 5 NO
89.1
71.1
79.80
15.70
19.70
Cysteine
Cys
C 3 H 5 NOS 121.2
103.1
85.10
11.60
13.60
Valine
Val
C 5 H 9 NO
117.1
99.1
84.60
12.00
14.10
Methionine
Met
C 5 H 9 NOS 149.2
131.2
87.90
9.40
10.70
Isoleucine
Ile
C 6 H 11 NO
131.2
113.2
86.30
10.70
12.40
Leucine
Leu
C 6 H 11 NO
131.2
113.2
86.30
10.70
12.40
Tyrosine
Tyr
C 9 H 9 NO 2
181.2
163.2
90.10
7.70
8.60
Phenylalanine
Phe
C 9 H 9 NO
165.2
147.2
89.10
8.50
9.50
Tryptophan
Trp
C 11 H 10 N 2 O 204.2
186.2
91.20
13.70
15.00
Lysine
Lys
C 6 H 12 N 2 O 146.2
128.2
87.70
19.20
21.90
Histidine
His
C 6 H 7 N 3 O
155.2
137.1
88.40
27.10
30.60
Arginine
Arg
C 6 H 12 N 4 O 174.2
156.2
89.70
32.20
35.90
Asparagine
Asn
C 4 H 6 N 2 O 2 132.1
114.1
86.40
21.20
24.60
Glutamine
Gln
C 5 H 8 N 2 O 2 146.1
128.1
87.70
19.20
21.90
Ammonia
–
NH 3
17
16
94.10
82.20
87.40
Water
–
H 2 O
1 8
–
–
–
–
Mass hydrogen –
H
1
–
–
–
–
Mass nitrogen
–
N
14
–
–
–
–
AA amino acid, AAA anhydrous amino acid, residue ¼ molecular weight of respective amino acid residue in a peptide or
protein polymer
240
L. M. L. Laurens et al.
Values used to calculate nitrogen-to-protein conversion factors (k A , k P , k)
Amino acid
Abbreviation
Molecular
formula
Avg.
mass
(Da)
Mass
residue
(Da)
Ratio
AAA/AA
(%)
%N in
AA (%)
%N in
AAA (%)
Aspartic acid
Asp
C 4 H 5 NO 3
133.1
115.1
86.50
10.50
12.20
Threonine
Thr
C 4 H 7 NO 2
119.1
101.1
84.90
11.80
13.90
Serine
Ser
C 3 H 5 NO 2
105.1
87.1
82.90
13.30
16.10
Glutamic acid
Glu
C 5 H 7 NO 3
147.1
129.1
87.80
9.50
10.80
Proline
Pro
C 5 H 7 NO
115.1
97.1
84.40
12.20
14.40
Glycine
Gly
C 2 H 3 NO
75.1
57.1
76.00
18.70
24.60
Alanine
Ala
C 3 H 5 NO
89.1
71.1
79.80
15.70
19.70
Cysteine
Cys
C 3 H 5 NOS 121.2
103.1
85.10
11.60
13.60
Valine
Val
C 5 H 9 NO
117.1
99.1
84.60
12.00
14.10
Methionine
Met
C 5 H 9 NOS 149.2
131.2
87.90
9.40
10.70
Isoleucine
Ile
C 6 H 11 NO
131.2
113.2
86.30
10.70
12.40
Leucine
Leu
C 6 H 11 NO
131.2
113.2
86.30
10.70
12.40
Tyrosine
Tyr
C 9 H 9 NO 2
181.2
163.2
90.10
7.70
8.60
Phenylalanine
Phe
C 9 H 9 NO
165.2
147.2
89.10
8.50
9.50
Tryptophan
Trp
C 11 H 10 N 2 O 204.2
186.2
91.20
13.70
15.00
Lysine
Lys
C 6 H 12 N 2 O 146.2
128.2
87.70
19.20
21.90
Histidine
His
C 6 H 7 N 3 O
155.2
137.1
88.40
27.10
30.60
Arginine
Arg
C 6 H 12 N 4 O 174.2
156.2
89.70
32.20
35.90
Asparagine
Asn
C 4 H 6 N 2 O 2 132.1
114.1
86.40
21.20
24.60
Glutamine
Gln
C 5 H 8 N 2 O 2 146.1
128.1
87.70
19.20
21.90
Ammonia
–
NH 3
17
16
94.10
82.20
87.40
Water
–
H 2 O
1 8
–
–
–
–
Mass hydrogen –
H
1
–
–
–
–
Mass nitrogen
–
N
14
–
–
–
–
AA amino acid, AAA anhydrous amino acid, residue ¼ molecular weight of respective amino acid residue in a peptide or
protein polymer
240
L. M. L. Laurens et al.