Principles of Biochemistry, Volume 1 - A. Lehninger 1985

Biomolecules
Proteins: Covalent Structure and Biological Functions
Some proteins contain not only amino acids but also other chemical groups in their composition

Many Proteins, such as the Enzymes Ribonuclease and Chymotrypsin, consist solely of Amino Acids and contain no other chemical groups; they are referred to as simple proteins. However, there are proteins that, upon Hydrolysis, yield other chemical components In addition to amino acids. These proteins are known as Conjugated Proteins. The non-protein part of a conjugated protein is usually called its prosthetic group. Conjugated proteins are classified According to the Chemical Nature of their prosthetic groups (Table 6-3). Lipoproteins contain Lipids, Glycoproteins incorporate sugars (from the Greek "glykos", meaning sweet), and Metalloproteins contain a specific metal characteristic of each, such as iron, copper, or zinc. Typically, the prosthetic group plays a crucial role in the protein's biological function.

Class="center">Table 6-3. Conjugated Proteins

Class

Prosthetic Group

Example

Lipoproteins

Lipids

Blood ß1-lipoprotein

Glycoproteins

CARBOHYDRATES

Blood у-globulin

Phosphoproteins

Phosphate groups

Milk casein

Hemoproteins

Heme (iron-protoporphyrin complex)

Hemoglobin

Flavoproteins

Flavin NUCLEOTIDES

Succinate dehydrogenase

Metalloproteins

Iron

Zinc

Ferritin

Alcohol dehydrogenase





Last update: 06/08/2026

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