Study on determination methods of chymosin potency / 中国生化药物杂志

ABSTRACT

Objective To investigate the influencing factors and improve potency methods of chymosin, to verify the stability and applicability of the national standard of chymosin.Methods The effects of different formula milk powder substrate and enzyme concentration on the determination of the activity of chymosin were studied.3 ×3 dose-response parallel line method was established.The results were compared with the different methods of absolute and relative methods.Results The different formula milk powder had a significant effect on the determination of the absolute potency of the activity of chymosin.The concentration of the enzyme was a power function relationship with the milk clotting time.Compared with the absolute potency, reproducibility of the relative potency of the results was better in different laboratories.The suitable doses in 3 ×3 dose-response parallel line method were 0.35,0.44,0.55U/mL.The confidence limit rate was less than 5%.The potency of the national standard of chymosin (140712-201302) was not significantly different between 2013 and 2015.In a certain dose range, the dose-response of the national standard of chimosin and gastropylor complex or lamb'tripe extract was linear, and the two lines were parallel.Conclusion A lot of factors can affect on the potency of chymosin.Relative potency is determinate by reference standard which can eliminate the influence of different substrates, different operators and endpoint judgment on the determination in order to make results have comparability between laboratories.The test design of 3 ×3 dose-response parallel line can control the test deviation better than the single point determination.The stability of the national standard of chymosin(140712-201302) is good, and is suitable for the potency of chymosin of the products of gastropylor complex and the extract of the lamb.