Collagen & Human Tissue

Structure and Distribution of an Unrecognized Interstitium in Human Tissues
Collagen: Animal Sources and Biomedical Application
from Wiki:

Amino acid Abundance in
mammal skin
(residues/1000)
Abundance in
fish skin
(residues/1000)
Glycine
G
329 339
Proline
P
126 108
Alanine
A
109 114
Hydroxyproline 95 67
Glutamic acid
Q
74 76
Arginine
R
49 52
Aspartic acid
D
47 47
Serine
S
36 46
Lysine
K
29 26
Leucine
L
24 23
Valine
V
22 21
Threonine
T
19 26
Phenylalanine
F
13 14
Isoleucine
I
11 11
Hydroxylysine 6 8
Methionine
M
6 13
Histidine
H
5 7
Tyrosine
Y
3 3
Cysteine
C
1 1