Protein and Peptide Letters - Volume 11, Issue 6, 2004

The activity and secondary structure of horseradish peroxidase (HRP) was studied in aqueous solution containing α-, β- and γ-cyclodextrin (CD). The results showed that the activity of HRP was enhanced to different extents by the three kinds of CD. A Fourier Transform infrared (FTIR) spectroscopy study indicated that the amount of α-helical structure was important for the activity of HRP. This phenomenon is discussed.

HMG-17 proteins are nucleosomal proteins, implicated in control of chromatin structure and transcription, in a way that has not yet been fully understood. In this report, quantification of HMG-17 in porcine tissues was performed, by ELISA, using previously produced and characterized specific rabbit anti- HMG-17 antibodies. Our results showed high levels of HMG-17 compared to the DNA and H1 content of the tissues (on the contrary to previous reports), and more specifically that there were 1.7 molecules of HMG-17 per molecule of histone H1.

We have identified MAZR and Rgl2 as specific interacting partners for kringle domains in angiostatin (K1-4) and K5 using yeast two hybrid screening. Both K1 and K1-4 have strong interaction with MAZR and Rgl2 whereas K5 only binds with Rgl2. No interaction of K2, K3, and K4 with either of these binding proteins was detected. We suggest that a common binding motif may exist near LBS-4 that is required for binding with Rgl2 but not with MAZR.

After consideration of the tertiary structure of the pY+3 binding pocket in SH2 domains, isoleucine of Ac-pYEEIE was replaced with various unnatural aliphatic amino acids and the binding affinities for Lck, Src, and Fyn SH2 domains were measured. We determined the characteristics of the amino acid at the pY+3 position in the phosphopeptide ligands for the specificity for the SH2 domains.

In this paper, we used correlation analysis to quantify the correlations between the hydrophobicity sequence and accessibility sequence of 26 α-helix bundle membrane proteins and 119 transmembrane helices. Statistical significances of these correlations were also assessed. A slightly positive correlation was found in the α-helix bundle membrane proteins due to the contribution of extramembranous domains. No correlation was found in the transmembrane domains.

This paper describes a convenient synthesis of protected hydrazine derivatives, i.e. 1,2-bis-Bochydrazinoacetic acid, and its application for hydrazone ligation techniques in convergent template assembled synthetic protein (TASP) synthesis.

Yeast alcohol dehydrogenase is slowly denatured at moderate hydrostatic pressure (t1 / 2 ? 30 min at 2 kbar and pH 7). The extent of denaturation is pH dependent with maximal stability near the isoelectric point of the protein, pH = 5.4. While not a surprising finding, it appears that this phenomenon has not been documented before (or at least not identified) despite many investigations into the pressure stability of proteins. Consideration of changes in the net charge of proteins far from their isoelectric points may explain other pressure effects as well.

A high swelling resin, CLPSER has been developed and utilized for the solid phase synthesis of Pardaxin, which is an 18-residue peptide. The resin was characterized by gel phase 13C NMR, IR and SEM. The utility of the new polymer support in polypeptide synthesis was further established by the comparative synthesis of pardaxin with commercially available Merrifield resin. The MALDI TOF MS, amino acid analysis and the HPLC revealed the superior quality of CLPSER.

Plants antiviral proteins are being used as anticancer agents and inhibit other viral diseases in humans. We modified the purification protocol of the two N-terminally blocked antiviral glycoproteins, CCP-25 and CCP-27, purified from the leaves of Celosia cristata. This not only gave rise to single pure samples with few steps of purification but also resulted in N-terminally free proteins. The extra purity of the samples was analyzed by reverse phase HPLC. Deglycosylation studies of CCP-25 with PNGase F enzyme revealed that its asparagine or asparagine-linked glycon contents are negligible. Partial N-terminal sequence of the CCP-25 showed the sequence (ANDIS), which seems to be conserved among plant antiviral proteins.

The mushroom Paecilomyces japonica, grown on the silkworm larvae, has been used in Asia as a nutraceutical, tea, and Chinese medicine. In the present study, a sialic acid-specific lectin has been purified from the mushroom P. japonica using affinity chromatography on a fetuin-agarose column. Electrophoretical analyses indicated that this lectin, designated P. japon ica agglu tinin (PJA), is an acidic protein with a molecular mass of 16 kDa, and has no intermolecular disulfide bonds. PJA induced hemagglutination activity in human ABO, mouse, rat, and rabbit erythrocytes. This activity was inhibited by sialic acid and sialoglycoproteins, but not by any other carbohydrates. PJA was stable at pH 4.0-8.0, and at temperatures below 55°C. The activity of PJA was independent of EDTA and divalent cations. In addit ion, PJA exerts cytotoxic effects on the following cancer cell lines: human stomach cancer SNU-1, human pancreas cancer AsPc-1, and human breast cancer MDA-MB-231.

The spatial ordering information of amino acid residue in protein primary sequence is an important determinant of protein three-dimensional structure. In this paper, we describe a radial basis function neural network (RBFNN), whose hidden centers and basis function widths are optimized by a genetic algorithm (GA), for the purpose of predicting three dimensional spatial distance location from primary sequence information. Experimental evidence on soybean protein sequences indicates the utility of this approach.

Cassava storage roots result from swelling of adventitious roots by secondary growth. In the present study we aimed to gain insight into the molecular processes occurring during cassava storage root formation. We report a comparative gene expression study in adventitious and storage roots in order to identify genes possibly related to storage organ formation. Our results revealed five genes with higher expression levels in secondary xylem of storage roots than adventitious roots. Among them, the Mec1 gene coding for Pt2L4 glutamic acid-rich protein and a putative RING Zinc Finger and LEA protein genes were strongly induced in secondary xylem tissue.

The interaction of activated papain with low molecular weight cystatin (Mr 12500) purified from human placenta has been studied. Analysis of inhibition of caesinolytic activity of papain by cystatin showed stoichiometry of 1:1. Kinetic studies gave an inhibition constant (Ki) value of 5.5 x 10 -8 M and association rate constant (K+1) value of 3.4 x 10 4 (M-1 s-1). All spectroscopic studies showed conformational changes in both papain and cystatin on formation of complex. The data suggest perturbation of environment of aromatic residues and change of their native structure and conformation thereby shedding light on the behaviour of cystatins, especially interaction of placental cystatin with thiol protease inhibitors.

Though protein folding is a regular phenomenon inside the cellular milieu, slight differences in the folding pattern of proteins may lead to disease-causing forms. Many diseases have been identified that are caused by these misfolded macromolecules and a considerable amount of focus is still directed towards better understanding of the processes that lead to these misfolded structures. Further progress in the field of how soluble proteins begin to misfold and how resultant oligomers begin dysfunction offers exciting prospects for specific molecular intervention.

The furyl group of (2-furyl)-L-alanine-containing peptides obtained from Fmoc solid-phase synthesis is partially degraded to several by-products during the final TFA-mediated deprotection in the presence of cation scavengers such as ethanedithiol and propanedithiol. The major by-product corresponds to a bis-dithioacetale formed after acidic hydrolysis of the furyl group. We examined several cleavage conditions and found that cleavage cocktails containing water and triisopropylsilane or 3,6-dioxa-1,8- octanedithiol (DODT) in trifluoroacetic acid are sufficient to minimize the side reaction.