Identification of soybean peptide leginsulin variants in different cultivars and their insulin-like activities

Abstract

We have recently reported that green soybean cultivar, echigomidori, and not the yellow cultivar, fukuyutaka, is a rich source of hormone-like peptide leginsulin consisting of 37 amino acids (Leg_1_37, PDB 1JU8A) and its C-terminal glycine deletant, Leg_1_36. Green soybean is mature, but the color of the seedcoat and cotyledon remains green. Therefore, in this study, we examined the leginsulin content in different varieties of 11 colored soybeans (including green, yellow, red, brown and black) and edamame (immature soybean). Profile analysis of soybean constituents by LC-MS showed that Leg_1 (36 + 37) detected as a prominent peak in 3 green and 1 yellow soybean cultivar was the strongest contributor in principal component analysis, indicating Leg_1 is the most characteristic feature for distinguishing soybean cultivars. However, smaller amounts of leginsulin-like peptides, defined as Leg_2 and Leg_3, were detected in other samples. The cDNA sequences and LC-MS/MS analyses revealed that Leg_2 was a homologue of Leg_1 with three amino acid substitutions derived from SNPs, while Leg_3 was a Leg_1/Leg_2 paralog. Expression levels of Leg_1 were markedly higher than Leg_2 and Leg_3. Additionally, in glucose uptake assay, purified TRX-His-tag fused recombinant Leg_1_37 prepared by bacterial expression showed stronger insulin-like activities than other variants including Leg_2, Leg_3, and their Gly deletants in myotube-like differentiated L6 and C2C12 cells. These results suggest that dietary consumption of soybean seed, especially including a higher amount of Leg_1_37, could be useful for lowering of blood glucose.

Novel o-Toluidine Metabolite in Rat Urine Associated with Urinary Bladder Carcinogenesis

“…The residues dissolved in 50 μL of 50% methanol were subjected to LC-MS consisting of AQUITY UPLC (Waters, Milford, MA) coupled with micrOTOFQII (Bruker Daltonics, Bremen, Germany). UPLC separation , was performed with a BEH C18 column (1.7 μm, 50 mm × 2.1 mm i.d., Waters) at 40 °C, using solvent A (0.1% formic acid in water) and solvent B (MeCN containing 0.1% formic acid). Samples were eluted from the column using a linear gradient of 1% solvent B from 0 min to 99% solvent B at 10–12 min.…”

o-Anisidine Dimer, 2-Methoxy-N4-(2-methoxyphenyl) Benzene-1,4-diamine, in Rat Urine Associated with Urinary bladder Carcinogenesis

“…The residues were dissolved in 50% MeOH (50 μL) and subjected to LC-MS, consisting of an ACQUITY Ultraperformance liquid chromatography (UPLC) (Waters, Milford, MA) coupled with a micrOTOF-Q II (Bruker Daltonics, Bremen, Germany). UPLC separation − was performed with an Ethylene Bridged Hybrid (BEH) C18 column (1.7 μm, 50 mm × 2.1 mm i.d., Waters) at 40 °C, using solvent A (0.1% formic acid in water) and solvent B (MeCN containing 0.1% formic acid). Samples were eluted from the column using a linear gradient starting at 1% solvent B (0 min) to 99% solvent B at 10–12 min.…”

Hydrolyzed Proteins and Vegetable Peptides: Anti-Inflammatory Mechanisms in Obesity and Potential Therapeutic Targets

“…In another study, by Hashidume et al [ 40 ], soy-derived peptides had insulin-like action in skeletal muscle cells (rat L6 and mouse C2C12). The studied peptides were leginsulin 1_36 and 1_37; the difference between them is a GLY residue in the C-terminal.…”

“…Furthermore, among the vegetable peptides, the peptide Leg (Leg_1_37 and Leg_1_36) [ 40 ] was able to increase the activity of the phosphatidylinositol 3-kinase (PI3K) and AKT pathways, favoring GLUT-4 translocation and assisting in the reduction of IR, minimizing IR and improving inflammation.…”

“…Studies have their limitations, either by the experimental model used or by the study design, which do not cancel the possibility of effects by other mechanisms. Among the 13 included studies using peptide pools, one study addressed the improvement in the profile of enzymes related to hepatic detoxification [ 30 ], seven analyzed the reduction in oxidative stress and increased antioxidant activity [ 25 , 26 , 29 , 30 , 33 , 36 , 37 ], five studies found reduction in NF-κB [ 24 , 26 , 39 , 42 , 45 ], two verified glucose uptake pathways [ 39 , 40 ] and all 13 analyzed inflammatory cytokines, mainly TNF-α and IL-1β, and improvements in immunomodulation [ 24 , 25 , 26 , 27 , 29 , 30 , 33 , 36 , 37 , 39 , 40 , 42 , 45 ].…”