摘要
研究了Ca2+对菠萝蛋白酶活性及远紫外圆二色谱的变化。在37℃下,Ca2+与酶作用1h后,5～10mmol/L Ca2+对酶的活性均有促进作用,其中当Ca2+浓度为2mmol/L时,促进作用最明显。在60℃下,Ca2+浓度为3mmol/L时,对菠萝蛋白酶的热稳定化效果最好,处理100min后仍然能保留68%的活性;菠萝蛋白酶在60℃下活性的半衰期为86min,除Ca2+浓度为1mmol/L外,其他浓度(2、3、4、5mmol/L)的Ca2+与菠萝蛋白酶作用后,酶的半衰期均有所延长。由圆二色谱曲线发现,菠萝蛋白酶在波长209nm与221nm处有明显的负峰。与Ca2+作用后菠萝蛋白酶的α-螺旋、β-转角和无规则卷曲均有所变化,其中,在37℃下加入Ca2+后,菠萝蛋白酶的α-螺旋均减少,而β-转角有所增加。在70℃下处理1h,Ca2+对菠萝蛋白酶二级结构也有所影响。无Ca2+处理的菠萝蛋白酶和加入4mmol/LCa2+的菠萝蛋白酶的α-螺旋分别减少为34.90%和35.60%,而β-转角则有所增加,分别为26.30%和25.10%。圆二色谱结果表明,α-螺旋结构对菠萝蛋白酶的稳定性起关键作用。
The effect of calcium ions on activity and Far-UV circular dichroism（CD）spectra of bromelain was studied.It was found that calcium ions evidently promote the bromelain＇ s activity when the concentration of Ca^2＋ was 2mmol/L at 37℃.The stability of bromeiain treated by various Ca^2＋ concentrations were promoted on 60℃ compared with no - treatment bromelain, especially at 3mmol/L that bromelain activity still hold 68% of no-treatment enzyme,and its half life increased compared with the pure bromelain＇ s half life.The Far-UV circular dichroism spectra of both native and Ca^2＋-bromelain showed two negative peaks at around 209nm and 221nm.The （α-helix,β-turn and random were changed when bromelain were treated by Ca^2＋ at 37℃,with the decrease of （α-helix and the increase of β-turn.When Ca^2＋ reacted with bromelain 1h at 70℃,the secondary structure of bromelain changed,which the （x-helix＇ content of native and Cat^2＋-bromelain decrease separately to 34.90% and 35.60% ,and the β-turn increased separately to 26.30% and 25.10%. Far-UV circular dichroism spectra showed that α-helix has important effects on the stability of bromelain.
出处
《食品工业科技》
CAS
CSCD
北大核心
2009年第1期153-155,158,共4页
Science and Technology of Food Industry
基金
2007年粤港关键领域重点突破项目(2007498612)
省部产学研合作项目(2007B090100009)
