Protein catabolism
Encyclopedia
Protein catabolism is the breakdown of protein
s into amino acid
s and simple derivative compounds, for transport into the cell through the plasma membrane and ultimately for the polymerisation into new proteins via the use of ribonucleic acids (RNA
) and ribosome
s. Protein catabolism, which is the breakdown of macromolecules, is essentially a digestion
process.
Protein catabolism is most commonly carried out by non-specific endo- and exo-proteases. However specific proteases are used for cleaving of proteins for regulatory and protein trafficking purposes. One example is the subclass of proteolytic enzymes called oligopeptidase
.
The amino acids produced by catabolism may be directly recycled, used to make new amino acids, or undergo amino acid catabolism to be converted to other compounds via the Krebs cycle.
See also: amino acid synthesis
.
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
s into amino acid
Amino acid
Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...
s and simple derivative compounds, for transport into the cell through the plasma membrane and ultimately for the polymerisation into new proteins via the use of ribonucleic acids (RNA
RNA
Ribonucleic acid , or RNA, is one of the three major macromolecules that are essential for all known forms of life....
) and ribosome
Ribosome
A ribosome is a component of cells that assembles the twenty specific amino acid molecules to form the particular protein molecule determined by the nucleotide sequence of an RNA molecule....
s. Protein catabolism, which is the breakdown of macromolecules, is essentially a digestion
Digestion
Digestion is the mechanical and chemical breakdown of food into smaller components that are more easily absorbed into a blood stream, for instance. Digestion is a form of catabolism: a breakdown of large food molecules to smaller ones....
process.
Protein catabolism is most commonly carried out by non-specific endo- and exo-proteases. However specific proteases are used for cleaving of proteins for regulatory and protein trafficking purposes. One example is the subclass of proteolytic enzymes called oligopeptidase
Oligopeptidase
Oligopeptidase is an enzyme that cleaves peptides but not proteins, a property that is due to its structure: the active site of this enzyme is located at the end of a narrow cavity which can only be reached by peptides...
.
The amino acids produced by catabolism may be directly recycled, used to make new amino acids, or undergo amino acid catabolism to be converted to other compounds via the Krebs cycle.
See also: amino acid synthesis
Amino acid synthesis
For the non-biological synthesis of amino acids see: Strecker amino acid synthesisAmino acid synthesis is the set of biochemical processes by which the various amino acids are produced from other compounds. The substrates for these processes are various compounds in the organism's diet or growth...
.
See also
- AnabolismAnabolismAnabolism is the set of metabolic pathways that construct molecules from smaller units. These reactions require energy. One way of categorizing metabolic processes, whether at the cellular, organ or organism level is as 'anabolic' or as 'catabolic', which is the opposite...
- MetabolismMetabolismMetabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...