Purification and Primary Structure Determination of a Novel Polypeptide Isolated from Mistletoe Viscum coloratum

A novel polypeptide was isolated from mistletoe Viscum coloratum. The primary structure of the polypeptide named viscotoxin B2 was determined to be KSCCKNTTGRNIYNT CRFAGGSRERCAKLSGCKIISASTCPSDYPK by Edman degradation. Viscotoxin B2 shared high sequence homology with viscotoxins isolated from Viscum album. Pharmacological experiments showed that viscotoxin B2 had distinct cytotoxic activity on tumor cells. Viscotoxin B2 could be used as a leading compound in cancer therapy.

Cubic Mesoporous Aluminosilicate with Primary Structure Units of Zeolite Beta in the Pore Wall

Mesoporous aluminosilicate with cubic ordered structure was synthesized by two-step crystallization, which showed stronger acid sites and more effective activity for catalytic alkylation of 2, 4-ditert-butylphenol with tert-butanol than conventional H-AlMCM-48 materials.

Effect of RE Oxide on Impact Toughness and Primary Structure of Surfacing Metal

The effect of rare earth(RE) oxide on impact toughness and primary structure of surfacing metal was investigated . The results show that the impact toughness of surfacing metal containing RE oxide can be increased by 50 %. The primary structure can be refined and its shape changed from columnar crystals to equiaxed ones.

THE PRIMARY STRUCTURE OF ARROWHEAD PROTEINASE INHIBITOR

After the reduction and carboxymethylation of disulfide bonds, arrowhead proteinase inhibitors A and B were cleaved either by proteinases or by cyanogen bromide, the fractionated and purified peptides were then subjected to sequencing by a gas phase automatic sequencer, the primary structures were completed by the alignment of the peptides sequenced with overlapping peptides. Both inhibitors A and B consist of 150 amino acid residues with three pairs of disulfide bonds, share 90% homology in structure, and are markedly different from all other Ser proteinase inhibitors so far known. Hence, the arrowhead inhibitor may belong to a new inhibitor family. Based on their structure characteristics, it was deduced that both their two reactive sites might be located in the positions of Lys-Ser (45-46) and Arg-Tyr-Lys (77-79), respectively. Among 13 mutated residues in inhibitors A and B, the substitution of residue Arg in position 87 of inhibitor B for residue Leu in A might be the main cause of leading to

Primary structure of p-momorcharin, a ribosome-inactivating protein from the seeds of Momordica Charantia Linn (Cucurbitaceae)

The complete amino acid sequence of β-momorcharin, a ribosome-inactivating protein from the seeds of Momordica charantia Linn (Cucurbitaceae) has been determined. This has been done by the sequence analysis of peptides obtained by enzymatic digestion with trypsin, chymotrypsin and S. aureus V8 protease, as well as by chemical cleavage with BNPS-skatole. The protein consists of 249 amino acid residues containing one asparagine - linked sugar group attached to the site of Asn 5 1 and has a calculated relative molecular mass of 28,452 Da without addition of the carbohydrate. Comparison of this sequence with those of trichosanthin and other ribosome-inactivating proteins from different species of plants shows a significant homology with each other. Regarding the similarity of their biological properties, an active domain of these proteins has been predicted here.

Studies on the primary structure of chicken apolipoprotein A-I using HPLC technique

The complete amino acid sequence of chicken plasma apolipoprotein(apo)A-I was determined by sequencing overlapping peptide fragments produced by trypsin,S.aureus V8 protease, and cyanogen bromide cleavage respectively.All of the peptide fragments were purified on a Waters or on a Beckman HPLC system with a Vydae C_(18) column using 0.1% TFA in water as buffer A,and 0.08% TFA in 95% acetomtrile and 5% water as buffer B.Most of the peaks separated by these systems were pure.The partially purified fractions were subjected to rechromatography with a Hypersil ODS column using 0.005M sodium phosphate,pH 6.0,as buffer A,and 90% acetonitrile and 10% water as buffer B.The N-terminus of chicken apo A-I was determined to be aspartic acid by directly sequencing the intact protein up to 30 residues,while the C-terminus was identified as alanine by carboxypeptidase Y cleavage.There are 240 amino acid residues in mature chicken apo A-I.By direct analysis of cyanogen bromide peptide,we also determined the sequence of a 6 amino acid prosegment,which is present at approximately 10% of the molar amount of the mature protein in chicken plasma.

A STUDY OF THE STRUCTURE AND THE EXPRESSION OF PROTOONCOGENES IN HUMAN PRIMARY GASTRIC CANCER

The allelic distribution of EcoRI and BamHI fragments of ras family genes between the human primary gastric cancer tissues and the corresponding adjacent normal tissues did not show any differences. Three genotypes of BamHI restriction fragments length polymorphism of c-H-ras were revealed. No significant differences in the RFLPs were observed between normal individuals and gastric cancer patients. Four protooncogenes, c-H-ras, N-ras, c-myc and c-fos, were found to be transcriptionally active in the gastric cancer tissues in some cases examined. The comparison of the expression of these oncogenes between the malignant tissues and the corresponding normal tissues showed differential patterns. The expression of c-H-ras at cellular level was detected with in situ hybridization. The enhanced expression of c-H-ras in the gastric cancer cells was demonstrated, but the degree of the expession among the cancer cells was shown to be heterogeneous. In addition, the enhanced expression of c-H-ras was seen in the inflammatory cells.

Study of quantum well mixing induced by impurity-free vacancy in the primary epitaxial wafers of a 915 nm semiconductor laser

Output power and reliability are the most important characteristic parameters of semiconductor lasers.However,catas-trophic optical damage(COD),which usually occurs on the cavity surface,will seriously damage the further improvement of the output power and affect the reliability.To improve the anti-optical disaster ability of the cavity surface,a non-absorption window(NAW)is adopted for the 915 nm InGaAsP/GaAsP single-quantum well semiconductor laser using quantum well mix-ing(QWI)induced by impurity-free vacancy.Both the principle and the process of point defect diffusion are described in detail in this paper.We also studied the effects of annealing temperature,annealing time,and the thickness of SiO_(2) film on the quan-tum well mixing in a semiconductor laser with a primary epitaxial structure,which is distinct from the previous structures.We found that when compared with the complete epitaxial structure,the blue shift of the semiconductor laser with the primary epi-taxial structure is larger under the same conditions.To obtain the appropriate blue shift window,the primary epitaxial struc-ture can use a lower annealing temperature and shorter annealing time.In addition,the process is less expensive.We also pro-vide references for upcoming device fabrication.

New Polypeptides from Chinese Mistletoe, Viscum coloratum (Kom.) Nakai

Three viscotoxins have been isolated from Chinese mistletoe, Viscum coloratura （Kom.） Nakai. The primary structures were determined unambiguously by the combination of Edman degradation, endoproteinase Elu-c digestion, and Q-TOF mass spectrometry. One was identified as viscotoxin C1, which was for the first time isolated from Chinese mistletoe. The other two were new polypeptides, named as viscotoxin B5 and viscotoxin B8. Pharmacological studies showed that the polypeptides exhibit distinct cytotoxicity to human cancer cells.

Primary Structural Characterization of Phospholipid Hydroperoxide Glutathione Peroxidase

More than 20 sequences of phospholipid hydroperoxide glutathione peroxidase (PHGPX) from a sequence database were analyzed. The analyses show that the primary structures of most PHGPX proteins have three highly conserved regions forming a catalytic center and have more than 50% amino acid sequence identity in common. However, two PHGPXs from bovine and swine with the same function have very low similarity with typical PHGPXs and do not have the three highly conserved regions. Thus, the PHGPX proteins are divided into two types: those with the three highly conserved regions, designated as PHGPX I, and the others as PHGPX II. In general, type I proteins are composed of ca.170 amino acid residues; a few of them have an extra signal peptide sequence at the N terminal of the protein. The composition of plant and animal PHGPX amino acids is very different, with most plant PHGPXs being weak acidic, while most animal ones are alkaline. Another specific conservative motif is also found in plant PHGPX proteins. System evolution analysis shows that ortholog and paralog evolution models both exist in PHGPXs, with the plant PHGPX and the animal PHGPX diverging exclusively into two branches in PHGPX I. The information revealed by the evolution tree agrees with the general species evolution process from low to advanced and from simple to complicated.