In the context of human physiology,antibodies are

In human physiology, antibodies (also known as immunoglobulins) are specialized proteins produced by plasma cells as part of the humoral immune response [t2]. Structurally, they are glycoproteins, meaning they consist of protein chains with attached carbohydrate groups [t2][t6]. Specifically, an antibody molecule is composed of four polypeptide chains—two heavy chains and two light chains—arranged in a Y-shaped structure [t1][t2]. These proteins constitute approximately 20% of the total protein found in human plasma [t2]. Their primary function is to recognize and bind to specific antigens, such as bacterial or viral proteins, to neutralize pathogens [t1][t2]. While they contain carbohydrate moieties, their fundamental chemical nature and classification in biological systems is as proteins (specifically globular proteins), distinguishing them from lipids, pure carbohydrates, or sterols [t2][t3].

Sources

1. [1] https://www.ncbi.nlm.nih.gov/books/NBK513460/
2. [2] https://www.nature.com/articles/s41392-024-01886-1
3. [3] https://www.sciencedirect.com/topics/immunology-and-microbiology/carbohydrate-antigen