Protein and Peptide Letters - Volume 12, Issue 2, 2005

The usage of protein folds in nature is known to be non-uniform: a few folds are used often, while most others are used relatively rarely. What makes one fold more successful than another? The designability explanation, which posits that successful folds have an exponentially larger number of compatible sequences, is critically reviewed, and compared with other structural and functional explanations. It is argued tha Read More

Protein engineering-based studies of the folding transition state have accelerated significantly in the last decade, and more than a half dozen proteins have been subjected to extensive -value analysis. A general picture is emerging from these studies of a transition state in which the large majority of experimentally characterized side chains participate in relatively homogeneous and energetically weak interactions playing o Read More

The small size and lack of disulphide bonds or cofactors in the Histidine-containing phosphocarrier protein (HPr) makes it an attractive system with which to study structure, interaction to its enzymatic partners, and its stability and folding. Here we give an overview on the immense work that has been performed on this protein and we will show that HPr has been widely used as a model protein to study important aspects in moder Read More

Proteins are involved in virtually every biological process and in order to function, it is necessary for these polypeptide chains to fold into the unique, native conformation. This folding process can take place rapidly. NMR line shape analyses and transverse relaxation measurements allow protein folding studies on a microsecondto- millisecond time scale. Together with an overview of current achievements within this field, Read More

The cyclotides are a large family of plant proteins that have a cyclic backbone and a knotted arrangement of three conserved disulfide bonds. Despite the apparent complexity of their cystine knot motif it is possible to efficiently fold these proteins, as exemplified by oxidative folding studies on the prototypic cyclotide, kalata B1. This mini-review reports on the current understanding of the folding process in cyclotides. The sy Read More

In contrast to their prohormones the mature peptide hormones guanylin and uroguanylin are not able to fold to their native disulfide connectivities upon oxidative folding. Structural properties of both peptide hormones and their precursor proteins as well as the role of their prosequences in proper disulfide coupled folding are reviewed. In addition, the structural behavior of a proguanylin mutant that closely resembles prouro Read More

From the time it was recognized that proteins are made up primarily of secondary structures, theories of protein folding have used secondary structural elements as important building blocks. Peptides have played a central role in elucidating the factors that stabilize individual elements of secondary structure and are now being employed to study higher levels of organization. The control of conformation in peptides has tak Read More

Cofactors are essential components of many proteins for biological activity. Characterization of several cofactor-binding proteins has shown that cofactors often have the ability to interact specifically with the unfolded polypeptides. This suggests that cofactor-coordination prior to polypeptide folding may be a relevant path in vivo. By binding before folding, the cofactor may affect both the mechanism and speed of folding. Her Read More

The study of amyloid polypeptide models (polypeptides able to generate amyloid structures not necessarily connected with any pathology) provides an excellent tool to increase the understanding of the generic aspects of misfolding and aggregation as well as the details of the mechanism of polypeptide deposition in disease. This knowledge can be integrated and applied to different problems in therapy and biotechnology, an Read More

While in vitro experiments have contributed much to our understanding of protein folding, we know much less about how proteins fold in the more complex environment of the cell. This review summarizes our current knowledge of the earliest in vivo folding intermediates: the conformations adopted by nascent polypeptides during synthesis by the ribosome. The challenges related to successful folding in the cellular environm Read More

The study explores in vitro by circular dichroism and mass spectrometry the effects of pH, Cu+2 ions and sheetbreakers on the secondary structures and self-aggregation of b-amyloid peptides [Aβ43, Aβ42 and Ab40] of Alzheimer's disease. Within pH 5.4-7.3, more sheet structures and aggregates containing up to 11 peptide units were observed. Cu+2 ions led to oxidative degradation or aggregation depending on its co Read More

In our earlier communications, we reported the effect of salts and alcohols on a-chymotrypsinogen [1] and the existence of stable intermediates at low pH in bromelain [2] and glucose oxidase [3]. In the present study, the role of metal ions and EGTA on the conformation of concanavalin A at alkaline pH was studied by near- and far-UV circular dichroism, fluorescence emission spectroscopy and binding of a hydrophobic dye, 1 Read More

We developed a simple immobilisation method for His-tagged enzymes on a microchannel surface. It facilitates immobilisation of protein molecule on microchannel surface through Ni-complex, using crude or purified protein solutions. By this method, we could immobilize proteins on microcapillary constantly. This method might be useful for further development of microreactor with reversibly immobilized enzymes.