The suitable time in the measurement of phenoloxidase activity

The absorbancy after the reaction between the serum phenoloxidase of Procambarus clarkii and L-DOPA was measured by Ashida′s spectrophotometry per 2 minutes and the results of phenoloxidase activity were calculated at different time in 60 minutes.The results showed that when the phenoloxidase activity was higher,the linear relationship between absorbancy and time was gradually poorer as measuring time was 60 minutes,which indicated that the measured results of phenoloxidase activity were not accurate and reliable.This phenomenon was the same as the results in previous reports of Penaeus vannamei,Penaeus chinesis,Eriocheir sinensis and Pieris rapae.Compared to the linear relationship and calculated results as measuring time was 6 minutes,the linear relationship lowered significantly as measuring time was longer than 12 minutes,and the linear relationship lowered a little also as measuring time was shorter than 6 minutes;the calculated results lowered significantly as measuring time was longer than 10 minutes.The suitable measuring time(t)of phenoloxidase activity was 6 minutes≤t10 minutes and the most suitable one was 6 minutes which was obtained by analyzing the linear relationship between absorbancy and measuring time and calculating results of phenoloxidase activity at different time.