Synthetic buckwheat pollen peptide BPP 1(A P V L Q I K K T G S N) and its analogues BPP 2\[( D )A P V L Q I K K T G S N NH 2\], BPP 3(A P A L Q L K K N G S Q G NH 2) showed different binding behavior to rape pollen ca...Synthetic buckwheat pollen peptide BPP 1(A P V L Q I K K T G S N) and its analogues BPP 2\[( D )A P V L Q I K K T G S N NH 2\], BPP 3(A P A L Q L K K N G S Q G NH 2) showed different binding behavior to rape pollen calmodulin(pCaM). Fluorescence titration experiments demonstrated that BPP 1 had no affinity for pCaM while its C terminal amide, BPP 2, had fair affinity for pCaM(dissociation constant of pCaM peptide complex, K d=2.9× 10 -1 μmol/L) due to the decrease in \{C terminal polarity.\} But compared with BPP 3( K d=8.1× 10 -2 μmol/L), which was also a peptide amide, BPP 2 had a much lower binding ability. In order to investigate other factors influencing peptide affinity for pCaM besides polarity(or hydrophobicity), CD and 2D NMR spectroscopes were used to study the conformations of BPP 1 and BPP 3. It revealed that molecular flexibility could affect peptides ability to bind pCaM. BPP 1 displayed rigid extended peptide bonds in the middle region where the basic amino acid pair Lys 7 Lys 8 is located, flanked by flexible peptide segments on both terminals; while the middle five residue region of BPP 3 exhibited as very flexible segment. Such a structural character might facilitate BPP 3 to adopt a conformation contributive to the interaction of two Lys residues with the acidic residues of pCaM in its peptide binding site and resulted in higher affinity. As this study revealed, both of the two peptides showed the lack of ordered structure in the aqueous solution. It seemed that there was no relationship between peptide affinity for CaM and the propensity of peptide chain to form α helix. This contradicted what most previous researches approved that α helix was an important character of peptide with high affinity for CaM.展开更多
The basic phospholipase A2 from the venom of Agkistrodon halys pallas possesses the ability to cause hemolysis in contrast to the other two phospholipase A2 from the same venom. A new form of crystals of this enzyme w...The basic phospholipase A2 from the venom of Agkistrodon halys pallas possesses the ability to cause hemolysis in contrast to the other two phospholipase A2 from the same venom. A new form of crystals of this enzyme was grown. The crystals belong to space group of P212121 with unit cell parameters of a=9. 175nm, b=10.080nm , c=2.287nm.The crystals diffract to high resolution, and are suitable for detailed structural studies. The data were collected up to 0.25nm resolutiorl using synchrotron radiation-imaging plate-Weissenberg camera system. Preliminary analysis reveals the presence of two molecules in the asymmetric uint and the molecule may pack with the smallest dimension approximately parallel to the c axis. The new crystal form is more attractive than the monoclinic one previously reported for crystallographic structure determination as it contains fewermolecules in the asymmetric unit.展开更多
The Crystals of acidic phospholipase A2 from the venom of Agkistrodon blomhoffii bre-vicaudus (i.e. Agkistrodon halys pallas) covalently modified with p-bromo-phenacylbromide wereobtained by the method of hanging drop...The Crystals of acidic phospholipase A2 from the venom of Agkistrodon blomhoffii bre-vicaudus (i.e. Agkistrodon halys pallas) covalently modified with p-bromo-phenacylbromide wereobtained by the method of hanging drop vapor diffusion. Crystallization droplet was composedof 0.06mol’L-1 Na(CH3)2AsO2 (pH=6.5), 24.8% (v/v) 1,4-butanediol, and 4.5mg.mL-1 protein.The crystal data are ot a=b=82.82A., c=32.85A, space group P61. 8945 unique reflections with1.93A resolution were ineasured on a Siemens area detector X-ray diffractometor, of which 8069reflections haring F0 >2σ(F). The experimental results show that the crystals are suitable to astructure analysis of high resolution.展开更多
文摘Synthetic buckwheat pollen peptide BPP 1(A P V L Q I K K T G S N) and its analogues BPP 2\[( D )A P V L Q I K K T G S N NH 2\], BPP 3(A P A L Q L K K N G S Q G NH 2) showed different binding behavior to rape pollen calmodulin(pCaM). Fluorescence titration experiments demonstrated that BPP 1 had no affinity for pCaM while its C terminal amide, BPP 2, had fair affinity for pCaM(dissociation constant of pCaM peptide complex, K d=2.9× 10 -1 μmol/L) due to the decrease in \{C terminal polarity.\} But compared with BPP 3( K d=8.1× 10 -2 μmol/L), which was also a peptide amide, BPP 2 had a much lower binding ability. In order to investigate other factors influencing peptide affinity for pCaM besides polarity(or hydrophobicity), CD and 2D NMR spectroscopes were used to study the conformations of BPP 1 and BPP 3. It revealed that molecular flexibility could affect peptides ability to bind pCaM. BPP 1 displayed rigid extended peptide bonds in the middle region where the basic amino acid pair Lys 7 Lys 8 is located, flanked by flexible peptide segments on both terminals; while the middle five residue region of BPP 3 exhibited as very flexible segment. Such a structural character might facilitate BPP 3 to adopt a conformation contributive to the interaction of two Lys residues with the acidic residues of pCaM in its peptide binding site and resulted in higher affinity. As this study revealed, both of the two peptides showed the lack of ordered structure in the aqueous solution. It seemed that there was no relationship between peptide affinity for CaM and the propensity of peptide chain to form α helix. This contradicted what most previous researches approved that α helix was an important character of peptide with high affinity for CaM.
文摘The basic phospholipase A2 from the venom of Agkistrodon halys pallas possesses the ability to cause hemolysis in contrast to the other two phospholipase A2 from the same venom. A new form of crystals of this enzyme was grown. The crystals belong to space group of P212121 with unit cell parameters of a=9. 175nm, b=10.080nm , c=2.287nm.The crystals diffract to high resolution, and are suitable for detailed structural studies. The data were collected up to 0.25nm resolutiorl using synchrotron radiation-imaging plate-Weissenberg camera system. Preliminary analysis reveals the presence of two molecules in the asymmetric uint and the molecule may pack with the smallest dimension approximately parallel to the c axis. The new crystal form is more attractive than the monoclinic one previously reported for crystallographic structure determination as it contains fewermolecules in the asymmetric unit.
文摘The Crystals of acidic phospholipase A2 from the venom of Agkistrodon blomhoffii bre-vicaudus (i.e. Agkistrodon halys pallas) covalently modified with p-bromo-phenacylbromide wereobtained by the method of hanging drop vapor diffusion. Crystallization droplet was composedof 0.06mol’L-1 Na(CH3)2AsO2 (pH=6.5), 24.8% (v/v) 1,4-butanediol, and 4.5mg.mL-1 protein.The crystal data are ot a=b=82.82A., c=32.85A, space group P61. 8945 unique reflections with1.93A resolution were ineasured on a Siemens area detector X-ray diffractometor, of which 8069reflections haring F0 >2σ(F). The experimental results show that the crystals are suitable to astructure analysis of high resolution.
