蚕蛹不同溶解性蛋白的营养学评价及酶解物对血管紧张素转换酶的抑制活性

Nutrition Evaluation of Silkworm Pupal Proteins with Various Solubility and Inhibitory Activity of Their Enzymatic Digested Products to Angiotensin-converting Enzyme

分别对缫丝蚕蛹中的水溶性和碱溶性蛋白组分进行营养学评价,为高效开发蚕蛹食品提供依据;通过蚕蛹蛋白酶解产物对血管紧张素转换酶(ACE)的体外抑制活性试验,探讨蚕蛹蛋白作为天然降压药品原料的利用潜力。营养学分析表明:蚕蛹蛋白水溶性和碱溶性组分中的氨基酸种类齐全,且必需氨基酸占总氨基酸的质量分数分别为41.2%和39.2%,明显高于WHO推荐的氨基酸组成模式(>36%);蚕蛹水溶性蛋白有第1～第4限制性氨基酸(依次为亮氨酸、异亮氨酸、缬氨酸和苏氨酸),而蚕蛹碱溶性蛋白仅有第1和第2限制性氨基酸(依次为蛋氨酸+胱氨酸、异亮氨酸),2种溶解性蛋白的生物效价均较低,在开发利用中,应补充限制性氨基酸或与其它蛋白搭配使用,以提高产品的营养价值。体外ACE抑制活性试验表明,蚕蛹的水溶性蛋白和碱溶性蛋白的碱性蛋白酶酶解产物均具有较强的ACE抑制活性,IC50值分别为0.121、0.113 mg/mL,2种蛋白有可能成为降血压肽生产原料。

In order to provide reference for efficient development of food with silkworm pupae,the water-soluble and alkali-soluble protein fractions from silkworm pupae of reeled cocoons were evaluated on their nutritional quality.Their utilization potential as protein resources for preparing natural blood pressure reducing medicine was investigated through assaying the in vitro inhibition activity of their alcalase hydrolysates to angiotensin-converting enzyme（ACE）.Nutrition analysis showed that both water-soluble and alkali-soluble protein fractions had complete composition of amino acids with mass fractions of essential amino acids to total amino acids as high as 41.2% and 39.2% respectively,being obviously higher over the amino acid composition standard recommended by WHO（36%）.Leucine,isoleucine,valine and threonine were the 1st,2nd,3rd and 4th limiting amino acids respectively in water-soluble proteins from silkworm pupae.In alkali-soluble proteins from silkworm pupae,Met＋Cys and isoleucine were the 1st and 2nd limiting amino acids.Both protein frac-tions had quite low biological values.Therefore,while used in food preparation,they should be compensated through adding the limiting amino acids or be used in combination with other proteins.The results of in vitro ACE-inhibition assay showed that the alcalase hydrolysates of both protein fractions had strong inhibitory activity on ACE.Their IC50 values were 0.121 and 0.113 mg/mL,respectively,being potential protein resources for preparing ACE-inhibitory peptides.