鸡蛋果幼叶细胞质丙酮酸激酶的调节特性

鸡蛋果幼叶ＰＫｃ的Ｋｍ（ＰＥＰ）为０．０３７ｍｍｏｌ／Ｌ,Ｋｍ（ＡＤＰ）为０．０５ｍｍｏｌ／Ｌ,与成生叶相同。幼叶ＰＫｃ的效应物与成长叶的有较大差异,草酸和Ｃａ＾２＋对幼叶ＰＫｃ的抑制机制与成长叶相同,但亲和力不同,这可能反映了酶的非活性部位具有不同的构象。     

鸡蛋果幼叶细胞质丙酮酸激酶的调节特性

鸡蛋果幼叶ＰＫｃ的Ｋｍ（ＰＥＰ）为０．０３７ｍｍｏｌ／Ｌ,Ｋｍ（ＡＤＰ）为０．０５ｍｍｏｌ／Ｌ,与成长叶相同。幼叶ＰＫｃ的效应物与成长叶的有较大差异,草酸和Ｃａ２＋对幼叶ＰＫＣｃ抑制机制与成长叶相同,但亲和力不同,这可能反映了酶的非活性部位具有不同的构象。     

Zn^2＋对鸡蛋果细胞质丙酮酸激酶的抑制作用

Zn2 抑制鸡蛋果 ( Passiflora edulis Smis)长成叶与幼叶细胞质丙酮酸激酶 ( PKC)活性 ,抑制程度决定于 Mg2 浓度大小。Zn2 的抑制作用在长成叶 PKC与幼叶 PKC之间表现出一定差异 :当改变 PEP或 ADP浓度时 ,以双倒数作图 ,Zn2 对长成叶和幼叶 PKC均表现为反竞争性抑制 ,但抑制常数不同。Zn2 对长成叶 PKC的抑制常数为 Ki ( PEP) =0 .0 5 9mmol/L,Ki ( ADP) =0 .0 74 mmol/L,对幼叶 PKC的抑制常数 Ki ( PEP) =0 .0 38mmol/L,Ki ( ADP) =0 .0 2 mmol/L。Zn2 对长成叶 PKC与幼叶 PKC的 Ki( Mg2 )亦不同 ,分别为 0 .0 1 6mmol/L和0 .0 0 8mmol/L。这些结果进一步证明长成叶 PKC与幼叶 PKC的酶学性质不同     

照光对鸡蛋果绿色组织细胞质丙酮酸激酶活性的影响

鸡蛋果叶片照光１５ｍｉｎ后,其成长叶ＰＫ和ＰＫｃ活性降低,幼叶ＰＫ和ＰＫｃ活性提高。鸡蛋果成长叶ＰＫｃ受［ＡＴＰ］／［ＡＤＰ］比值调节,受ＤＴＴ轻微抑制。ＤＴＴ和生理浓度ＡＴＰ对鸡蛋果幼叶ＰＫｃ活性无显著影响。这表明鸡蛋果成长叶ＰＫｃ光下受抑制可能与光下［ＡＴＰ］／［ＡＤＰ］比值提高有关。     

水稻叶片磷酸烯醇式丙酮酸磷酸酯酶活性及其部分特性

从水稻（Ｏｒｙｚａ ｓａｔｉｖａ）叶片分离出对磷酸烯醇式丙酮酸（ＰＥＰ）较专一的ＰＥＰ磷酸酯酶,其Ｋｍ （ＰＥＰ）为０．４２ ｍ ｍ ｏｌ／Ｌ,作用ｐＨ范围较窄,最适ｐＨ ８．７。它在ｐＨ ６．２—９．５ 范围内及４０℃以下较稳定。Ｐｉ对酶活性影响不大,仅在大于５ ｍ ｍ ｏｌ／Ｌ时表现出轻微的抑制作用。Ｍｇ２＋ 对酶活性具激活作用,在Ｍｇ２＋ 存在条件下,ＣａＣｌ２、ＣｏＣｌ２、ＣｕＳＯ４、ＦｅＳＯ４ 和ＺｎＳＯ４ 均表现抑制作用     

照光对鸡蛋果绿色组织细胞质丙酮酸激酶活性的影响

鸡蛋果叶片照光１５ｍｉｎ后,其成长叶ＰＫ和ＰＫｃ活性降低,幼叶ＰＫ和ＰＫｃ活性提高。鸡蛋果成长叶ＰＫｃ受［ＡＴＰ］／［ＡＤＰ］比值调节,受ＤＴＴ轻微抑制。ＤＴＴ和生理浓度ＡＴＰ对鸡蛋果幼叶ＰＫｃ活性无明显影响。这表明鸡蛋果成长叶ＰＫｃ光下受抑制可能与光下［ＡＴＰ］／［ＡＤＰ］比值提高有关。     

丙酮酸磷酸双激酶及其基因结构

丙酮酸磷酸双激酶（PPDK）在植物C4光合途径中催化CO2原初受体磷酸烯醇式丙酮酸（PEP）的形成。本文介绍PPDK的类型、分布、生理功能、活性调节、基因结构和C4植物的PPDK基因转化C3植物及其与转基因植株光合作用之间关系的研究进展。     

氮素营养对丙酮酸磷酸二激酶的调节（简报）

成熟苋菜和玉米叶片以 KNO_3为主要氮源的完全营养液离体培养时,可溶性蛋白质和PPDK酶活性随氮浓度增加而增加,环己酰亚胺(20μmol/L)和水杨醛肟(0.5mmol/L )抑制可溶性蛋白质含量和PPDK酶活性。光下氮素促进PPDK酶活性的提高。     

小分子代谢物对黑曲霉己糖激酶和丙酮酸激酶的酶活调控

黑曲霉是柠檬酸的工业生产菌株,糖酵解中的3个不可逆反应是柠檬酸积累的重要调控节点,但己糖激酶和丙酮酸激酶的代谢调控研究相对较少,本研究旨在加深对己糖激酶和丙酮酸激酶代谢调控的认识.首先,将黑曲霉己糖激酶和丙酮酸激酶进行内源过表达,经GST亲和层析纯化后重组酶的比酶活分别为(4.86±0.14)U/mg和(1.83±0....     

Inhibition Effect of Zn2+ on Cytosolic Pyruvate Kinase in Passiflora edulis Leaves

Cytosolic pyruvate kinase (PKc) activity in both mature and young leaves of Passiflora eclulis Smis was inhibited by Zn2+, and the severity of inhibition was dependant upon the concentration of Mg2+ present in the solution . Some differences in the inhibitory kinetics existed between PKc in mature and young leaves. Zn2+ showed anti-competitive inhibition of PKc in both mature and young leaves with respect to PEP and ADP, Ki′ (PEP) were 0. 059 mmol/L and 0. 038 mmol/L, and Ki′ (ADP) were 0. 074 mmol/L and 0.02 mmol/L respectively for PKc in mature and young leaves. Ki (Mg2+) of Zn2+ on PKc in both mature and young leaves were 0. 016 mmol/L and 0. 008 mmol/L respectively. These results further substantiated our previous conclusion that the in regulatory properties of PKc in mature leaves were different from those in young leaves.     

Glycosidic Inhibitors of Melanogenesis from Leaves of Passiflora edulis

A new flavonoid glycoside, chrysin 6‐C‐β‐rutinoside (chrysin α‐L ‐rhamnopyranosyl‐(1→6)‐C‐β‐glucopyranoside; 2 ), and two new triterpene glycosides, (31R)‐31‐O‐methylpassiflorine ( 7 ) and (31S)‐31‐O‐methylpassiflorine ( 8 ), along with 14 known glycosides, including three flavonoid glycosides, 1, 3 , and 4 , six triterpene glycosides, 5, 6 , and 9 – 12 , three cyano glycosides, 13 – 15 , and two other glycosides, 16 and 17 , were isolated from a MeOH extract of the leaves of Passiflora edulis (passion flower; Passifloraceae). The structures of new compounds were elucidated on the basis of extensive spectroscopic analysis and comparison with literature data. Upon evaluation of compounds 1 – 17 against the melanogenesis in the B16 melanoma cells induced with α‐melanocyte‐stimulating hormone (α‐MSH), three compounds, isoorientin ( 1 ), 2 , and (6S,9R)‐roseoside ( 17 ), exhibited inhibitory effects with 37.3–47.2% reduction of melanin content with no, or almost no, toxicity to the cells (90.8–100.2% cell viability) at 100 μM . Western blot analysis showed that compound 2 reduced the protein levels of MITF, TRP‐1, and tyrosinase, in a concentration‐dependent manner while exerted almost no influence on the level of TRP‐2, suggesting that this compound inhibits melanogenesis on the α‐MSH‐stimulated B16 melanoma cells by, at least in part, inhibiting the expression of MITF, followed by decreasing the expression of TRP‐1 and tyrosinase. In addition, compounds 1 – 17 were evaluated for their inhibitory effects against the Epstein? Barr virus early antigen (EBV‐EA) activation induced by 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA) in Raji cells.     

黄果西番莲中的一个新内酯类成分

从黄果西番莲(Passiflora edulisSims)压榨果汁中分离得到一个新的内酯类成分,波谱技术鉴定其结构为西番莲内酯。该化合物未显示对DPPH自由基的清除活性。     

Antihypertensive Effect of an Extract of Passiflora edulis Rind in Spontaneously Hypertensive Rats

Orally administered methanol extract of Passiflora edulis rind (10 mg/kg or 50 mg/kg) or luteolin (50 mg/kg), which is one of consistent polyphenols of the extract, significantly lowered systolic blood pressure in spontaneously hypertensive rats (SHRs). Quantitative analysis by liquid chromatography tandem mass spectrometry (LC-MS/MS) showed that the extract contained 20 μg/g dry weight of luteolin and 41 μg/g dry weight of luteolin-6-C-glucoside. It also contained γ-aminobutyric acid (GABA, 2.4 mg/g dry weight by LC-MS/MS or 4.4 mg/g dry weight by amino acid analysis) which has been reported to be an antihypertensive material. Since the extract contained a relatively high concentration of GABA, the antihypertensive effect of the extract in SHRs might be due mostly to the GABA-induced antihypertensive effect and partially to the vasodilatory effect of polyphenols including luteolin.     

Parkin Regulates the Activity of Pyruvate Kinase M2

Parkin, a ubiquitin E3 ligase, is mutated in most cases of autosomal recessive early onset Parkinson disease. It was discovered that Parkin is also mutated in glioblastoma and other human malignancies and that it inhibits tumor cell growth. Here, we identified pyruvate kinase M2 (PKM2) as a unique substrate for parkin through biochemical purification. We found that parkin interacts with PKM2 both in vitro and in vivo, and this interaction dramatically increases during glucose starvation. Ubiquitylation of PKM2 by parkin does not affect its stability but decreases its enzymatic activity. Parkin regulates the glycolysis pathway and affects the cell metabolism. Our studies revealed the novel important roles of parkin in tumor cell metabolism and provided new insight for therapy of Parkinson disease.     

丙酮酸激酶前mRNA可变剪接的调控在肿瘤代谢中的作用和意义

丙酮酸激酶是糖酵解的关键酶之一,丙酮酸激酶m基因前mRNA(pre-mRNA)通过可变剪接产生M1和M2型两种丙酮酸激酶异构体,2种异构体的选择性表达决定肿瘤细胞的代谢表型,改变肿瘤细胞的增殖和生长。因此,调控丙酮酸激酶可变剪接,对于控制肿瘤细胞的生长代谢十分重要。研究发现,核不均一核糖核蛋白(hnRNP)A1/A2及多聚嘧啶结合蛋白(PTB,又称hnRNPⅠ)具有调控丙酮酸激酶前mRNA可变剪接的作用,并且致癌转录因子c-Myc与hnRNP A1/A2及PTB在肿瘤细胞中的过表达密切相关。我们结合相关研究进展,简要综述丙酮酸激酶可变剪接调控机制。     

植物类受体胞质激酶的结构和功能

本文介绍植物类受体胞质激酶的结构及其在植物的抗病、抗逆、生长发育、自交不亲和、油菜素内酯信号转导等方面的功能。     

Pyruvate Kinase Activity in Crude Extracts of Leaves of Cynodon dactylonand Other C4Plants

A new extraction procedure and an LDH-coupled assay method are presented for the study of pyruvate kinase (PK) in leaf crude extracts from Cynodon dactylon(L.) Pers and other C₄plants. Extraction at pH 6.8 and assay at pH 6.2 facilitated the measuring of PK activity by eliminating phosphoenolpyruvate carboxylase interference more effectively than the thermal inactivation or chemical inhibition previously used. The method suggested did not affect the kinetic properties of PK as compared to the purified enzyme from C. dactylon.