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 constitutes t...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 pancreaticβcells.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 pancreaticβcell.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 pancreaticβcells.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 pancreaticβcell.
