1. School of Environment and Resource, Guangxi Normal University, Guilin 541004, China 2. Department of Material and Chemical Engineering, Guilin University of Technology, Guilin 541004, China
Abstract:In pH 6.5 phosphate buffer solutions, dodecyl benzene sulfonate (SDBS) was combined with casein to form association particles, which exhibited five Rayleigh scattering peaks at 470, 360, 400, 420 and 520 nm, respectively. Under suitable conditions, papain has catalytic effect on the hydrolysis of casein, and SDBS can stop the catalytic reaction and be combined with the excess casein to form association particles. The scattering peak at 470 nm decreased with the activity of papain. The ΔI470 nm value was linear with the papain activity in the range of 0.048-4.8 USP·mL-1. Its regress equation is ΔISDBS=1.972c+2.31,with a related coefficient of 0.999 9 and detection limit of 0.020 USP·mL-1. This new assay has been applied to the assay of the papain activity in food additive with satisfactory results.
[1] Hong L, Hai Y W, Chang H X, et al. Enzyme and Microbial Technology, 2002, 31: 588. [2] Kumara A B, Varadarajb M C, Lalithac R G, et al. Biochimica et Biophysica Acta, 2004,1670:137. [3] FENG Jian-wen(冯健雯). Phy. Tes. Chem. Anal. Chem. Part B(理化检验, 化学分册),2001,37(6): 277. [4] LUO Yuan-xiu(罗远秀). Chin. J. Pharm.(中国药学杂志),2000,35: 556. [5] WEI Yong-ju, KANG Zhi-min, LIU Cui-ge, et al(魏永巨, 康志敏, 刘翠格, 等). Spectroscopy and Spectral Analysis(光谱学与光谱分析), 2004, 24(12): 1659. [6] LI Zhen-zhong, JIANG Zhi-liang, YANG Guang, et al(李振中, 蒋治良, 杨 光, 等). Spectroscopy and Spectral Analysis(光谱学与光谱分析), 2005, 25(8): 1286.