What is the difference between Glu-plasminogen and Lys-plasminogen? How can the two forms be measured?

The native form of plasminogen in plasma has glutamic acid (Glu) at the N-terminal and is termed Glu-plasminogen. Other plasminogen forms generated by the catalytic cleavage of plasmin and containing mostly lysine (Lys) at the N-terminal position are termed Lys-Plasminogen. They can be measured using a chromogenic method based on the different rate of activation of the two forms by urokinase. See Scully MF, Kakkar VV. Measurement of Degraded Forms of Plasminogen in Human Plasma. Thromb Res (1980); 17: 347-352. Note that the Chromogenix plasminogen is at least 95% Glu-plasminogen.