ACADEMIC INFORMATION
Hemostasis
[Technology]
(International Units and Enzyme Activity) Urokinase
관리자(bioms@hanmail.net)
2020.07.22조회 1486 |
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Urokinase
Urinary type plasminogen activator (u-PA) is present either as a single chain proenzyme form (scu-PA) with a very low plasminogen activating activity or as an activated two-chain form (tcu-PA). tcu-PA occurs as both high molecular weight (HMW tcu-PA) or low molecular weight (LMW tcu-PA) enzyme species. HMW tcu-PA is 2-3 times more potent than LMW tcu-PA in biological assays such as the clot lysis method but their amidolytic activity on the chromogenic substrate S-2444 is equivalent (1) . The International Reference Preparation (IRP) of urokinase (66/46) was established by the Expert Committee on Biological Standardisation of the WHO in 1968 (2) . Until then urokinase was expressed in casein Ploug (Leo standard) or CTA units (CTA standard). These units were related to the amount of urokinase capable to hydrolyse a certain amount of casein in a defined time. 1 CTA-U was assumed to be identical to 1 International Unit (IU). Although there was no official numerical relationship between Ploug units and IU, 1.5 IU has been accepted to be equivalent to 1 Ploug unit. The IRP 66/46 is a mixture of 66% LMW and 34% HMW forms of tcu-PA (3) .
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