Biological Chemistry - Berezov, T. T., Korovkin, B. F. 1998
Protein Chemistry
Protein content in organs and tissues
Animal tissues and Organs are the richest in protein substances. Microorganisms and plants also serve as sources of protein. Most Proteins are readily soluble in Water. Certain organic substances isolated from Cartilage, Hair, Nails, horns, and Bone tissue that are insoluble in water have also been classified as proteins because their chemical composition is close to that of proteins found in Muscle tissue, Blood serum, and eggs.
In Muscles, Lungs, Spleen, and Kidneys, proteins account for more than 70–80% of the dry mass, whereas in the entire human body, they comprise 45% of the dry mass (Table 1.1) *. Unlike animal tissues, plants contain significantly fewer proteins (Table 1.2).
Class="center">Table 1.1. Protein content in human organs and tissues
|
Organs and tissues |
Protein content, % |
Organs and tissues |
Protein content, % |
||
of dry mass |
of total body protein |
of dry mass |
of total body protein |
||
63 |
11,5 |
Kidneys |
72 |
0,5 |
|
Bones (hard tissues) |
20 |
18,7 |
47 |
0,1 |
|
Teeth (hard tissues) |
18 |
0,1 |
|||
Striated |
80 |
34,7 |
Digestive |
63 |
1,8 |
muscles |
tract |
||||
Brain and Nervous Tissue |
45 |
2,0 |
Adipose tissue |
14 |
6,4 |
57 |
3,6 |
Other tissues: |
|||
60 |
0,7 |
fluid |
85 |
1,4 |
|
Lungs |
82 |
3,7 |
dense |
54 |
14,6 |
Spleen |
84 |
0,2 |
Whole body |
45 |
100 |
* A number of tables and figures in this textbook have been adapted from the manuals by B.I. Zbarsky, I.I. Ivanov, and S.R. Mardashev (Moscow, 1972) and Yu.B. Filippovich (Moscow, 1994).
Table 1.2. Protein content in animal organs and plants
Animal organs |
Protein content, % of fresh tissue mass |
Plant organs |
Protein content, % of fresh tissue mass |
Muscles |
18-23 |
Seeds |
10-13 |
Liver |
18-19 |
Stems |
1,5-3,0 |
Spleen |
17-18 |
Leaves |
1,2-3,0 |
Kidneys |
16-18 |
Roots |
0,5-3,0 |
Lungs |
14-15 |
Fruits |
0,3-1,0 |
Brain |
7-9 |
To study The chemical composition, Structure, and Properties of Proteins, they are typically isolated either from tissues, cultured Cells, or biological fluids, such as blood serum, milk, muscles, liver, skin, etc. Calculated on a dry matter basis, the Elemental Composition of proteins consists of 50–54% carbon, 21–23% oxygen, 6.5–7.3% hydrogen, 15–17% nitrogen, and up to 0.5% sulfur. Some proteins also contain small amounts of phosphorus, iron, manganese, magnesium, iodine, and other elements.
Thus, In addition to carbon, oxygen, and hydrogen, which are found in almost all organic polymer molecules, nitrogen is an essential component of proteins; consequently, proteins are generally classified as nitrogen-containing Organic compounds. The nitrogen content is more or less constant in all proteins (averaging 16%); therefore, the protein quantity in biological samples is sometimes determined based on their protein nitrogen content.
Last update: 06/08/2026
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