Exploitation of effective uses of Rubisco as highly functional food resources

二磷酸核酮糖羧化酶/加氧酶（Rubisco）是地球上最丰富的蛋白质，它在光合作用中催化二氧化碳的固定，占据了叶片蛋白质的1/3到1/2。作为一种特殊的植物蛋白，Rubisco从营养的角度来看具有理想的氨基酸组成。我们筛选了可能有助于预防Rubisco酶解过程中生活方式相关疾病的生物活性肽。Rubiscolin （Tyr Pro-Leu- Asp Leu- Phe）是一种δ阿片肽，从菠菜Rubisco的胃蛋白酶消化物中分离得到，口服剂量为100mg/kg，可改善小鼠的学习性能。它还表现出抗焦虑活性。从菠菜Rubisco的胃蛋白酶胰酶消化液中分离到4种血管紧张素转换酶抑制肽MRWRD、MRW、LRIPVA和IAYKPAG。其中，MRWRD、MRW和IAYKPAG在自发性高血压大鼠（SHR）口服后显示降压活性。以菠菜为原料制备Rubisco含量大于50%的粗蛋白质，用胃蛋白酶和胰酶消化。粗叶蛋白酶解物的ace抑制活性高于纯化rubisco酶解物。特别是，粗叶蛋白的胃蛋白酶消化表现出强大的抗高血压活性，表明摄入叶蛋白对预防高血压有效。从其他植物的Rubisco中也可以释放出相同的生物活性肽。Rubisco是一种理想的在小环境负荷下生产的蛋白质资源。Rubisco是降低大气二氧化碳的重要酶蛋白。这意味着Rubisco是一种非常重要的蛋白质，不仅是一种食物资源，而且在改善环境方面也很重要。

Ribulose bisphosphate carboxylase/oxygenase (Rubisco) which catalizes carbon dioxide fixation in photosynthesis is the most abundant protein on the earth since it occupys 1/3 to 1/2 of leaf proteins. Exceptionally as a plant protein, Rubisco has an ideal amino acid composition from nutritional point of view. We screened for bioactive peptides which might contribute to prevent lifestyle-related diseases in enzymatic digests of Rubisco. Rubiscolin (Tyr Pro-Leu- Asp Leu- Phe), which was isolated as a δ opioid peptide from a pepsin digest of spinach Rubisco, improved learning performance after oral administration at a dose of 100mg/kg in mice. It also exhibited anxiolytic activity. Four inhibitory peptides for angiotensin-converting enzyme, MRWRD, MRW, LRIPVA and IAYKPAG, were isolated from pepsin pancreatin digest of spinach Rubisco. Among them, MRWRD MRW and IAYKPAG showed hypotensive activity after oral administration in spontaneously hypertensive rats (SHR). Crude protein fraction of which Rubisco content was higher than 50% was prepared from spinach and digested with pepsin and pancreatin. ACE-inhibitory activities of the digests from the crude leaf protein were higher than those from purified rubisco. Especially, pepsin digest of the crude leaf protein exhibited potent antihypertensive activity suggesting that ingestion of leaf protein is effective in preventing hypertension. Essentially the same bioactive peptides could be released from Rubisco of other plant species. Rubisco is expected as an ideal protein resouce which could be produced under small environmental load.Rubisco is an important enzyme protein in lowering atmospheric carbon dioxide. This means that Rubisco is a very important proteins not only as a food resources but also in improving environment.