Protein and Peptide Letters - Volume 12, Issue 3, 2005

The three-dimensional structure of a protein depends on its amino acid sequence, as do the stability and the folding mechanism. The first milestones in the study of protein folding took place at the beginning of the 20th century: in 1911, Chick and Martin (J. Physiol. 43:1) showed that proteins can be denaturated; in 1931, Wu (Chin. Physiol. 1:219) showed that the process of denaturation involves unfolding; and in 1931, Read More

Proteins carry out many vital cellular functions determined by their precise 3-dimensional structures (the native conformations). Understanding how proteins fold has long been a major goal and can be of great therapeutic value. Failure to reach or maintain the correct folded structure can have serious consequences, as in the conformational diseases. The ultimate goal of folding studies is to predict structure from sequence Read More

Basic concepts about two-state, cooperative protein folding and its relation to first-order phase transitions are reviewed. Minimalist models capable of reproducing the required free energy barrier between folded and unfolded macroscopic states are described. A significantly more restrictive “calorimetric” criterion is also discussed, which is based on direct comparison between model and experimental heat capacities with ad Read More

Apomyoglobin (apoMb) folds through at least two partially folded forms that are detected both as transient intermediates during folding/unfolding kinetics or as stable intermediates at equilibrium. Here, I summarize the results of recent kinetic studies, which combined with detailed characterizations of equilibrium forms of the protein, provide a very detailed picture of apoMb folding process. The data are consistent Read More

Protein dynamics and thermodynamics can be characterized through measurements of relaxation rates of side chain 2H and 13C, and backbone 15N nuclei using NMR spectroscopy. The rates reflect protein motions on timescales from picoseconds to milliseconds. Backbone and methyl side chain NMR relaxation measurements for several proteins are beginning to reveal the role of protein dynamics in protein stability and ligand binding.

5-Hydroxytyptophan is a fluorescent tryptophan analog that can be incorporated into recombinant proteins expressed in E. coli and is particularly useful in studies of biological systems that involve supermolecular aggregates of more than one protein. Here we review the varied applications of 5-hydroxytryptophan to study structure, interactions, conformational change and dynamics in complex protein systems.

High hydrostatic pressure (HHP) is a powerful tool to study protein folding and the dynamics and structure of folding intermediates. Aggregates and amyloids, derived from partially folding intermediates at the junction between productive and off-pathway folding, have been studied as well, which promises better understanding of the protein misfolding diseases. Here is summarized the recent data we have collected with transthyr Read More

The main hypothesis for prion diseases proposes that the cellular protein (PrPC) can be altered into a misfolded, β-sheet-rich isoform (PrPSc). We describe here that host nucleic acid may catalyze the conversion between PrPC and PrPSc isoforms, by reducing the protein mobility and by making the protein-protein interactions more likely. We summarize the findings, focusing in the biological relevance of the catalytic action of nucleic acid.

Molecular chaperones are one of the most important cell defense mechanisms against protein aggregation and misfolding. These specialized proteins bind non-native states of other proteins and assist them in reaching a correctly folded and functional conformation. Chaperones also participate in protein translocation by membranes, in the stabilization of unstable protein conformers and regulatory factors, in the deliv Read More

Calcitonin (CT), a peptide hormone that is widely used for the treatment of osteoporosis, Paget's disease, hypercalcemic shock and chronic pain in terminal cancer patients, is produced by the para-follicular cells of the thyroid gland in mammals and by the ultimobranchial gland of birds and fish. Fish calcitonin, like eel calcitonin (eCT), is more potent and longer lasting than human CT and is one of the many bioactive peptides that Read More

Copper was added to truncated, recombinant cystathionine β-synthase (CBS), and the enzyme activity was assessed by measuring the production of cystathionine. 10microM copper significantly decreased CBS activity by 50% while 25microM copper decreased CBS activity by 70%. This inhibition was negated when an analog of the N-terminus of human albumin, Asp-Ala-His-Lys (DAHK), a strong transition metal binding p Read More

Peptide analogues of Tendamistat which include the most essential residues linked by novel w-amino acids (X,Y,Z: H2N-(CH2)n-CO2H, where n=2-10) were designed, synthesized (Ac-Tyr15-X-Trp18-Arg19-Tyr20-Y-Thr55-Z-Asp58- Gly59-Tyr60-Ile61-Gly62-NH2), and analyzed for α-amylase inhibitory activity. Native dipeptide spacers sometimes were left intact at X and Z. Analogues demonstrated competitive inhibition with Ki Read More

A practical method for the synthesis of an important precursor of constrained peptides involving only three steps from commercial inexpensive precursors is reported.

The mutation, conferring streptomycin and deoxyglucose resistance on cells, had profound effect on the kinetic and thermodynamic parameters inferring thermostabilization of ß-glucosidase from mutant 51 SMr of Cellulomonas biazotea. Free energy of activation for substrate binding, enthalpy and entropy of activation for irreversible denaturation of mutant-derived enzyme were decreased compared with enzyme fro Read More

To investigate the role of arginine in the folding of D-aminoacylase, seven arginine residues, R26, R152, R296, R302, R354, R377, and R391, among twelve arginine residues highly conserved in D-aminoacylase, N-acyl-D-aspartate amidohydrolase (D-AAase), and N-acyl-D-glutamate amidohydrolase (D-AGase) from Alcaligenes xylosoxydans subsp. xylosoxydans A-6 (Alcaligenes A-6) were substituted with lysine by site- Read More

In yeast two-hybrid system, rat 12-lipoxygenase (12-LO) bound to complete (390 amino acids) or the Nterminus truncated form of human p47 phox, but not to the C-terminus truncated form (residues 1-286). When glutathione S-transferase fused human p47phox was added to an in vitro 12-LO enzyme activity assay, formation of 12- hydroperoxyeicosatetraenoic acid was reduced significantly compared to the C-terminus Read More

We have purified and characterized pig and bovine milk lactadherins. Studies by circular dichroism spectroscopy indicate that the two proteins present a similar folding pattern. Results have been discussed in terms of their affinity for pig zona pellucida in order to use these proteins as analogs of pig sperm lactadherin in gamete studies.