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The rubiscolins are a group of opioid peptides that are formed during digestion of the ribulose bisphosphate carboxylase/oxygenase (Rubisco) protein from spinach leaves.[1] These peptides have much in common with the better-known gluten exorphins.

Types of Rubiscolin[edit]

There are 2 known rubiscolins with known structure:


  • Structure: H-Tyr-Pro-Leu-Asp-Leu-OH


  • Function: can have an anxiolytic effect via activation of sigma1 and dopamine D1 receptors.[2]
  • Structure: H-Tyr-Pro-Leu-Asp-Leu-Phe-OH

Studies on Rubiscolin[edit]

Studies have been conducted on rubiscolin structure and biological responses following its digestion.[3][4] The tertiary structure and biological function of spinach-derived rubiscolin has been analyzed in the laboratory.[3] When rubiscolin is digested, studies have shown that rubiscolin has the potential to bind to δ opioid receptors in the body.[3] The analysis of the amino acids responsible for this agonistic relationship of rubiscolin with δ opioid receptors can lead to replication of these proteins in the lab.[3] Rubiscolin has the capability to bind to δ opioid receptors following its digestion.[3] Upon the digestion of rubiscolin from spinach with the protease pepsin, peptides MRWRD, MRW, LRIPVA, AND IAYKPAG were found and purified.[4] These peptides were found to have binding capabilities with angiotensin I-converting enzyme (ACE), which catalyze an antihypertensive, or decreased blood pressure, response.[4] When treated to rats in the laboratory, MRW, MRWRD, and IAYKPAG resulted in antihypertensive responses in hypertensive rats 2 hours, 4 hours, and 4 hours, respectively, after ingestion of the peptides.[4] The peptide LRIPVA did not induce any antihypertensive responses from laboratory rats.[4] The tertiary structure of rubiscolin has been mapped and the δ opioid receptor and ACE binding capabilities have been researched in the lab.[3][4]


  1. ^ Yang, Shuzhang; Yunden, Jinsmaa; Sonoda, Soushi; Doyama, Naomi; Lipkowski, Andrzej W; Kawamura, Yukio; Yoshikawa, Masaaki (2001). "Rubiscolin, a δ selective opioid peptide derived from plant Rubisco". FEBS Letters. 509 (2): 213–217. doi:10.1016/S0014-5793(01)03042-3. PMID 11741591. S2CID 83631217.
  2. ^ Hirata, H; Sonoda, S; Agui, S; Yoshida, M; Ohinata, K; Yoshikawa, M (2007). "Rubiscolin-6, a delta opioid peptide derived from spinach Rubisco, has anxiolytic effect via activating sigma1 and dopamine D1 receptors". Peptides. 28 (10): 1998–2003. doi:10.1016/j.peptides.2007.07.024. PMID 17766012. S2CID 54430089.
  3. ^ a b c d e f Caballero, Julio; Saavedra, Mario; Fernández, Michael; González-Nilo, Fernando D. (2007-10-01). "Quantitative Structure–Activity Relationship of Rubiscolin Analogues as δ Opioid Peptides Using Comparative Molecular Field Analysis (CoMFA) and Comparative Molecular Similarity Indices Analysis (CoMSIA)". Journal of Agricultural and Food Chemistry. 55 (20): 8101–8104. doi:10.1021/jf071031h. ISSN 0021-8561. PMID 17803260.
  4. ^ a b c d e f Yang, Yanjun; Marczak, Ewa D.; Yokoo, Megumi; Usui, Hachiro; Yoshikawa, Masaaki (2003-08-01). "Isolation and Antihypertensive Effect of Angiotensin I-Converting Enzyme (ACE) Inhibitory Peptides from Spinach Rubisco". Journal of Agricultural and Food Chemistry. 51 (17): 4897–4902. doi:10.1021/jf026186y. ISSN 0021-8561. PMID 12903942.

External links[edit]