Kallidin is a bioactive

kinin A kinin is any of various structurally related polypeptides, such as bradykinin and kallidin. They are members of the autacoid family. Kinins are peptides that are cleaved from kininogens by the process of kallikreins. Kallikreins activate kinins wh ...

formed in response to injury from

kininogen Kininogens are precursor proteins for kinins, biologically active polypeptides involved in blood coagulation, vasodilation, smooth muscle contraction, inflammatory regulation, and the regulation of the cardiovascular and renal systems. Types o ...

precursors through the action of

kallikrein Kallikreins are a subgroup of serine proteases, enzymes capable of cleaving peptide bonds in proteins. In humans, plasma kallikrein (encoded by ''KLKB1 gene'') has no known paralogue, while tissue kallikrein-related peptidases (''KLKs'') encode a f ...

s. Kallidin is a decapeptide whose sequence is H-Lys-Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg-OH. It can be converted to

bradykinin Bradykinin (BK) (Greek brady-, slow; -kinin, kīn(eîn) to move) is a peptide that promotes inflammation. It causes arterioles to dilate (enlarge) via the release of prostacyclin, nitric oxide, and endothelium-derived hyperpolarizing factor and ...

by the

aminopeptidase Aminopeptidases are enzymes that catalyze the cleavage of amino acids from the amino terminus (N-terminus) of proteins or peptides (exopeptidases). They are widely distributed throughout the animal and plant kingdoms and are found in many subcell ...

enzyme. It can be a substrate for

carboxypeptidase A carboxypeptidase ( EC number 3.4.16 - 3.4.18) is a protease enzyme that hydrolyzes (cleaves) a peptide bond at the carboxy-terminal (C-terminal) end of a protein or peptide. This is in contrast to an aminopeptidases, which cleave peptide bonds at ...

M and N. Kallidin is identical to

with an additional

lysine Lysine (symbol Lys or K) is an α-amino acid that is a precursor to many proteins. It contains an α-amino group (which is in the protonated form under biological conditions), an α-carboxylic acid group (which is in the deprotonated −C ...

residue added at the

N-terminal The N-terminus (also known as the amino-terminus, NH2-terminus, N-terminal end or amine-terminus) is the start of a protein or polypeptide, referring to the free amine group (-NH2) located at the end of a polypeptide. Within a peptide, the ami ...

end and signals through the

bradykinin receptor The bradykinin receptor family is a group of G-protein coupled receptors whose principal ligand is the protein bradykinin. There are two Bradykinin receptors: the B1 receptor and the B2 receptor. B1 receptor Bradykinin receptor B1 (B1) is a ...

References

Peptides Kinin–kallikrein system {{Biochem-stub