Nutrition Guide

Low-molecular-weight kininogen is a form of kininogen, which has been identified in mice,[1] guinea pigs,[2] and whales.[3]

Kininogens are proteins that are defined by their role as precursors for kinin, but that also can have additional roles.

The two main types are:
High-molecular-weight kininogen, which is produced by the liver together with prekallikrein. It acts mainly as a cofactor on coagulation and inflammation, and has no intrinsic catalytic activity.
Low-molecular-weight kininogen, which is produced locally by numerous tissues, and secreted together with tissue kallikrein.

A kinin is any of various structurally related polypeptides, such as bradykinin and kallikrein. They are members of the autacoid family.[1] They act locally to induce vasodilation and contraction of smooth muscle.[2][3] It is a component of the kinin-kallikrein system. Their precursors are kininogen.[4] In botany, it refers to plant hormones which delay aging.[5] Aspirin inhibits the activation of kallenogen by interfering with the formation of kallikrien enzyme which is essential in the process of activation.

Kallikreins are targets of active investigation by drug researchers as possible biomarkers for cancer.[2][3]

Prostate-specific antigen (PSA; hk3, human kallikrein gene 3) and human glandular kallikrein (hK2) are used as tumor markers for prostate cancer.

There are 15 known kallikreins: KLK1, KLK2, KLK3, KLK4, KLK5, KLK6, KLK7, KLK8, KLK9, KLK10, KLK11, KLK12, KLK13, KLK14, KLK15

They liberate kinins (BK and KD) from the kininogens.[1]

It also generates plasmin from plasminogen:
Prekallikrein is the precursor of plasma kallikrein. It can only activate kinins after being activated itself by factor XII or other stimuli.

Kallikreins (tissue and plasma kallikrein) are peptidases (enzymes that cleave peptide bonds in proteins), a subgroup of the serine protease family.

Kallidin is a bioactive kinin formed in response to injury from kininogen precursors through the action of kallikreins.

Kallidin is a decapeptide that can be converted to bradykinin by the aminopeptidase enzyme.

Kallidin is identical to bradykinin with an additional lysine residue added at the N-terminal end and signals through the bradykinin receptor.

Measurement of HMWK is usually done with mixing studies, where plasma deficient in HMWK is mixed with the patient’s sample and the PTT determined. Results are expressed in % of normal - values under 60% or over 140% are abnormal.

The practical importance of the discovery of bradykinin became apparent when one of his collaborators at the Medical School of Ribeirão Preto at the University of São Paulo, Dr. Sérgio Henrique Ferreira, discovered a bradykinin potentiating factor (BPF) in the bothropic venom which increases powerfully both the duration and magnitude of its effects on vasodilation and the consequent fall in blood pressure. On the basis of this finding, Squibb scientists developed the first of a new generation of highly-effective anti-hypertensive drugs, the so-called ACE inhibitors, such as captopril (trademarked Capoten).

Currently, bradykinin inhibitors, also known as antagonists, are being developed as potential therapies for hereditary angioedema. Icatibant is one such inhibitor. Additional bradykinin inhibitors exist. It has long been known in animal studies that bromelain, a substance obtained from the stems and leaves of the pineapple plant, suppresses trauma-induced swelling caused by the release of bradykinin into the bloodstream and tissues. [7] Other substances that act as bradykinin inhibitors include aloe [8] [9] and polyphenols, substances found in red wine and green tea. [10]