利用海藻酸在pH2.7的条件下对小分子多肽的吸附作用,从豌豆种子中分离并纯化出含37个氨基酸的小分子肽PA1b(pea albumin 1b),它的肽链内具有6个半胱氨酸并形成一个胱氨酸结构模体.采用荧光显微技术和膜片钳技术,发现胞外施加PA1b在胞外...利用海藻酸在pH2.7的条件下对小分子多肽的吸附作用,从豌豆种子中分离并纯化出含37个氨基酸的小分子肽PA1b(pea albumin 1b),它的肽链内具有6个半胱氨酸并形成一个胱氨酸结构模体.采用荧光显微技术和膜片钳技术,发现胞外施加PA1b在胞外钙离子存在的情况下使胰腺β细胞内钙离浓度增加,该效应被特异性的L型钙通道的阻断剂尼莫地平(nimodipine)阻断,在零钙外液中PA1b对胞内钙离子浓度无影响;此外,PA1b使β细胞膜去极化并使膜电容增加.因此推断PA1b使原代β细胞上去极化细胞膜,使L型钙离子通道开放,细胞外钙离子内流并促发细胞分泌.展开更多
Using alginic acid to adsorb polypeptides at pH 2.7, we isolated a peptide pea albumin 1b (PA1b) from pea seeds. The PA1b is a single chain peptide consisting of 37 amino acid residues with 6 cysteines which constitut...Using alginic acid to adsorb polypeptides at pH 2.7, we isolated a peptide pea albumin 1b (PA1b) from pea seeds. The PA1b is a single chain peptide consisting of 37 amino acid residues with 6 cysteines which constitutes the cystine-knot structure. Using microfluorometry and patch clamp techniques, we found that PA1b significantly elevated the intracellular calcium level ([Ca2+ ]i) and elicited membrane capacitance increase in the primary rat pancreatic β cells. The PA1b effect on [Ca2+]i elevation was abolished in the absence of extracellular Ca2+ or in the presence of L-type Ca2+ channel blocker, ni- modipine. Interestingly, we found that PA1b significantly depolarized membrane potential, which could lead to the opening of voltage-dependent L-type Ca2+ channels and influx of extracellular Ca2+, and then evoke robust secretion. In this study we identified the plant peptide PA1b which is capable of affecting the excitability and function of mammalian pancreatic β cell.展开更多
文摘利用海藻酸在pH2.7的条件下对小分子多肽的吸附作用,从豌豆种子中分离并纯化出含37个氨基酸的小分子肽PA1b(pea albumin 1b),它的肽链内具有6个半胱氨酸并形成一个胱氨酸结构模体.采用荧光显微技术和膜片钳技术,发现胞外施加PA1b在胞外钙离子存在的情况下使胰腺β细胞内钙离浓度增加,该效应被特异性的L型钙通道的阻断剂尼莫地平(nimodipine)阻断,在零钙外液中PA1b对胞内钙离子浓度无影响;此外,PA1b使β细胞膜去极化并使膜电容增加.因此推断PA1b使原代β细胞上去极化细胞膜,使L型钙离子通道开放,细胞外钙离子内流并促发细胞分泌.
基金the National Natural Science Foundation of China (Grant Nos. 30370674,30470448, and 30470646)the CAS Project (Grant No. KSCX2-SW-224)+1 种基金the China "863" Program (Grant No. 2012AA214066)The laboratory of Tao Xu is also supported by the Partner Group Scheme of the Max Planck Institute for Bio-physical Chemistry, Gttingen
文摘Using alginic acid to adsorb polypeptides at pH 2.7, we isolated a peptide pea albumin 1b (PA1b) from pea seeds. The PA1b is a single chain peptide consisting of 37 amino acid residues with 6 cysteines which constitutes the cystine-knot structure. Using microfluorometry and patch clamp techniques, we found that PA1b significantly elevated the intracellular calcium level ([Ca2+ ]i) and elicited membrane capacitance increase in the primary rat pancreatic β cells. The PA1b effect on [Ca2+]i elevation was abolished in the absence of extracellular Ca2+ or in the presence of L-type Ca2+ channel blocker, ni- modipine. Interestingly, we found that PA1b significantly depolarized membrane potential, which could lead to the opening of voltage-dependent L-type Ca2+ channels and influx of extracellular Ca2+, and then evoke robust secretion. In this study we identified the plant peptide PA1b which is capable of affecting the excitability and function of mammalian pancreatic β cell.
